Motorcycle Chassis Design Digest #771-780





MC-Chassis-Dgst       Monday, September 28 1998       Volume 01 : Number 771



 1. Bill Heckel            Subj: Re: Fixing wobbles (was MC-Chassis Intro.) BMW
 2. batwings@i-plus.net                  Subj: Re: Fixing wobbles (was MC-Chassis Intro.) BMW
 3. JBAKER1@aol.com                      Subj: Re: MC-Chassis El Mirage Land speed record
 4. "Tony Foale"        Subj: MC-Chassis Re: BMW stuff
 5. Andrew Fairbank    Subj: Re: MC-Chassis R100GS wobble
 6. Andrew Fairbank    Subj: Re: MC-Chassis Introduction
 7. "Joe Allan"        Subj: Re: MC-Chassis El Mirage Land speed record
 8. authier@ibm.net                      Subj: Re: MC-Chassis Introduction
 9. "Sam Stoney"      Subj: MC-Chassis Re: BMS Chassis stuff
10. uranus       Subj: Re: MC-Chassis El Mirage Land speed
11. batwings@i-plus.net                  Subj: Re: MC-Chassis Introduction
12. batwings@i-plus.net                  Subj: Re: MC-Chassis Re: BMS Chassis stuff

----------------------------------------------------------------------

Date: Sun, 27 Sep 1998 12:36:38 -0400
From: Bill Heckel 
Subject: Re: Fixing wobbles (was MC-Chassis Intro.) BMW

I have a 1975 R90/6 and it wobbles and wallows and pigs it's way down the road.  I had thought about working on the suspension and chassis until I bought a 1995 R100 Mystic.  That bike worked so much better that I decided to leave the old R90/6 alone as it would never handle or brake as well as the mystic.

As for the stupid, worthless top 'triple' on the R90/6, under braking and on impacts, it moves around.  I can put one hand on it and grab a big handful of brake and feel it shift position.  The bolts are all VERY tight, it just isn't a snug fit on the fork pivot.  The design sucks.

Where does one find an appropriate top clamp for that bike?

Hnry@aol.com wrote:
>  R100GS owner ... replacing BMW's stock rear
> shock ... " and he mentions its flaws ...
> 
> Why-how does the rear suspension cause the bike to weave or wobble? I'm
> guessing it's unsettled, pogo-ing?

IMHO, if the rear end is moving around, loading and unloading the rear tire, the tire flex will move the tail of the bike around. 

Also, bouncing the rear up and down changes the rake, trail, and steering angles on the front end.  

If these aren't damped out, oscillations are possible that can re-inforce each other resulting in a tank slapper.

Bill.

------------------------------

Date: Sun, 27 Sep 1998 13:42:35
From: batwings@i-plus.net
Subject: Re: Fixing wobbles (was MC-Chassis Intro.) BMW

At 12:36 PM 9/27/98 -0400, you wrote:
>Where does one find an appropriate top clamp for that bike?

There was an aftermarket item for a while. I don't recall who made it. If
you want one, I can make a unit out of plate which will be a whole lot
stronger. I would need a bottom clamp to work from, as I would want to take
locations straight off it and not rely on factory dimensions ... so often,
there are little diffs between the tops and bottoms because of slight
machining errors.
>

Hoyt

------------------------------

Date: Sun, 27 Sep 1998 16:21:40 EDT
From: JBAKER1@aol.com
Subject: Re: MC-Chassis El Mirage Land speed record

Rick, I don't know how big you are, but you might try raising the fairing
incrementally to see if it can improve your tuck position. Since these
fairings are very small, and essentially redirect the flow around things,
minor changes can have significant effects. Just food for thought

Jim

------------------------------

Date: Mon, 28 Sep 1998 00:29:31 +0200
From: "Tony Foale" 
Subject: MC-Chassis Re: BMW stuff

Sam said:

<<
I've
replaced more than one and never seen a change in front end stiffness. My
opinion is it's pretty damn hard to bend a 1/8 plate on it's flat axis;
particularly when it's held parrallel by three massive parallel bolts.
Intuitivly I don't believe it's a weak point and my experience backs up
that intuition. Not to say I can't be wrong - I seem to be a minority of
one when it comes to defending that particular design.
>>

You're in no minority of one, Sam.  I agree  with the above and then there
must be a few BMW people that do also.
I've ridden BMW twins for over 35 years, and started with the Earles'  fork
models which also used the flat plate at the top.  I've used them on the
road, in enduros and raced them.  I've done this with the standard fork
arrangement and with machined yokes and noticed no difference at all.
On most of the leading link forks that I built I went for a similar flat
plate idea (although welded to the stantions), subconciously inspired to a
large extent by the BMs. no doubt.
When you consider the loads imposed on that BMW plate it is quite an
appropriate design for the job.
I think you'll find that most opposition to the standard plate stems from
the fact that it's not how others do it, and it certainly doesn't look
"trick".

Tony Foale

Espaņa / Spain
http://www.ctv.es/USERS/Softtech/motos

------------------------------

Date: Sun, 27 Sep 1998 18:53:06 -0400
From: Andrew Fairbank 
Subject: Re: MC-Chassis R100GS wobble

Lauren wrote:

> At 05:10 PM 9/25/98 , Stephen Watson wrote:
> >To whom it may concern:
> >
> >I
> informed decisions about how to modify my Beemer to not toss me off when it
> gets crossed up - which it recently did at about 85-90. I have been told
> that late model BMW Airheads have a lot of flex in their frame and that
> stiffening the frame can have a postive impact.
>
> Since there seems to be very little traffic on this list for me to watch
> while lurking - maybe someone would care to comment on my supposed problems
> with my BMW frame

Lauren, I have a fair amount of experience with BMW R100GS handling; I'mboth a
currently certified tech and a GS owner. My approach to the high speed wobbles
that it sounds like your GS is having would be to first verify that all the
suspension/ drive
bearings are in spec then adjust your steering head bearing preload very
carefully.
      Bear in mind that having the preload too high is the
usual cause of high speed wobbles. (I'm assuming SH bearings in reasonably good
shape)
 What I'm getting at is that the GS shouldn't wobble at those speeds if it's
set up well.
   One more thing-what are you running for tires?
- -Andrew

------------------------------

Date: Sun, 27 Sep 1998 19:10:18 -0400
From: Andrew Fairbank 
Subject: Re: MC-Chassis Introduction

batwings@i-plus.net wrote:

>
>
> If your bike uses that shitty little sheet-netal top 'clamp' your problem
> will go away when you replace it with something having 3 dimensions. BMW
> went through a huge lawsuit about a decade ago where it was alleged and
> proven that the fork is legally defective. I don't know if they recalled
> them, but they did pay a huge settlement. Maybe you should simply see a
> lawyer and let BMW pay for your mods.
>
> Hoyt

That is an odd attitude for this list-Andrew

------------------------------

Date: Sun, 27 Sep 1998 17:43:00 -0700
From: "Joe Allan" 
Subject: Re: MC-Chassis El Mirage Land speed record

Rick wrote:
> 
> Hi Everybody
> I broke the El Mirage Land speed record On Sunday the 20 Th on my Turbo GSXR street bike...
>---------------------------snip--------------------------------------

Rick;
  Gongratulations...good job. I bet that was a rush eh:-)
 Seeins how you are into turbos, I have a  1972 SOHC750 Honda with one of 
the origional "American Turbo Pak" kits on it, the motor is strong enough 
to tear the rear wheel bearings out of the stock wheel and it makes the 
stock frame seem quite wimpy, so I,m waiting for the time to build a 
better frame for it or grab a ready made custom if it comes along. The 
bike had 40 miles on it when I picked it up:-) 
 Joe
(to many projects not enough time...sigh)

------------------------------

Date: Sun, 27 Sep 1998 19:49:14 -0700
From: authier@ibm.net
Subject: Re: MC-Chassis Introduction

batwings@i-plus.net wrote:
> 
> At 11:05 PM 9/25/98 -0700, you wrote:
> >weeks ago I came around a corner on a highway at a good clip (85-90 MPH)
> >and hit a slick spot, got crossed up, recovered and then the handlebars
> >started a series of tank slappers that eventually resulted in my parting
> >ways with the bike.
> 
> If your bike uses that shitty little sheet-netal top 'clamp' your problem
> will go away when you replace it with something having 3 dimensions. BMW
> went through a huge lawsuit about a decade ago where it was alleged and
> proven that the fork is legally defective. I don't know if they recalled
> them, but they did pay a huge settlement. Maybe you should simply see a
> lawyer and let BMW pay for your mods.
> 
> Hoyt

Oh yes, get a lawyer involved.

Marc

------------------------------

Date: Mon, 28 Sep 1998 00:44:57 -0700
From: "Sam Stoney" 
Subject: MC-Chassis Re: BMS Chassis stuff

Hoyt writes, regarding the infamous BMW sheet metal top clamp:

> 
> My own intuitions run counter to that (I was surprised to see one before
I
> even began riding motorcycles), and so did the careful analysis of the
> experts and engineers testifying. As for experience, I have replaced
stock
> but pinch-clamped factory trees with similar billets and had people tell
me
> they could feel the diff pushing it onto the trailer. And if you're the
> only one arguing something, listen to what others are telling you.

I do listen to what other people tell me; I just take nothing for gospel.
And I have heard numbers people tell me that they have seen substantial
improvments from Splitfires,  Duralube, BMW frame braces, and a variety of
other things. It is human nature to justify one's commitment, therefore the
opinion of the maker or purchaser of an item is -always- suspect. As
regards the experts and engineers testing - I expressed my desire to see
their commentary on the top clamp seriously - I am very curious about this.
And I'm probably wrong on this one - I'll admit it. But I'd like to see
some non-anecdotal evidence.

I'm not trying to discredit anyone - I'm just stating that what people say
in this case has not been what I've experienced. And I still don't
understand what is wrong with the design. I have never seen a properly
torqued one come loose. And I've never seen a difference after replacing
one. Street or race.

> Sorry, (the BMW frame) isn't (good enough) and it does need work. IMHO
the best improvements will be a
> proper top clamp and a SH-SA brace. If the bike doesn't have a deficiency
> in handling, a steering damper is not needed.
> 

Hoyt, I both agree and disagree with you completely. Yes, the BMW chassis
is a flexible flyer. But my point is that is is a well balanced flexible
flyer. If you brace the swing arm ( a very good thing) and strengthen the
front end (however you want to do it- I have a K1 front end on my Rbike,
and a braced swingarm), then the frame just gets worse. To get the thing
right will probably take replacing everything but the motor. Where do you
stop? My contention is that in some cases you're better off living with
what you have, and maybe hiding a few faults with a steering damper, and a
good shock. Oh - and most race bikes have steering dampers - does that mean
that they are deficient? 

Look: I'm not saying my way is the right way, I just hate to see people
throw money at things just because every else does. Lauren - do whatever
you want - just don't believe something works just because a bunch of
people say it works. Try to tweak the system you have before you get
drastic. Check the steering head and swingarm bearings, make sure the
springs are set up for you and your riding and ride the darn thing. Then
think real hard before you buy the top clamp or the swingarm pivot: Is this
going to make the bike better for me? would the money be better spent on a
riding school?

One last thing - I never follow my own advice. I can't ever leave well
enough alone. Next step for me and my Rbike is a new complete chassis.
That's what I think it will take to cure it. 

Do what makes you happy.

Sam  

------------------------------

Date: Mon, 28 Sep 1998 10:42:27
From: uranus 
Subject: Re: MC-Chassis El Mirage Land speed

At 09:30 27/09/98 -0700, you wrote:
>I tried using as much as 250 lbs. of ballast right in front of the rear tire
>without much effect . For the record I had 115 lbs.. of ballast.
>I know the aerodynamics of the bike aren't to good
>any ideas????????????
>Here is a current picture
>http://www.geocities.com/MotorCity/Downs/4762/dyno2.JPG

The GSX-R fairing is truly hopeless aerodynamically.  A dustbin fairing
would be the one for lowest Cd, but look at e.g. Honda Super Blackbird to
see some slightly more modern thinking.  A much more all-enveloping front
mudguard would help loads, as would something to smooth the riders' back
into the tail unit.  All of these would make a great difference at the
speeds you're talking about, but perhaps you're restricted by some kind of
silhouette regs.?

Crosswind stability: I don't think I would want to push my luck on that . .
. in fact I think I would insist on absolute dead air before trying to ride
your bike at all!  

Fairing generated lift:  realistically you must build some kind of lift
measuring device (simple enough) and build up the speed progressively
before going for it.  You mind need some kind of front wing/spoiler.

  
David T. (never been over 140mph) 

------------------------------

Date: Mon, 28 Sep 1998 06:50:38
From: batwings@i-plus.net
Subject: Re: MC-Chassis Introduction

At 07:49 PM 9/27/98 -0700, you wrote:
>> 
>Oh yes, get a lawyer involved.

Do I sense sarcasm? They may be a bit of an unpopular solution, but if BMW
made a bad design move and if it is a factor in crashes (which IMHO they
did and it is), then anyone would be a fool not to take advantage of
remediation. And if as in most cases there is a certain amount of
argy-bargy involved, it's no skin off anyone's nose but BMW's collective
nose, to have a lawyer involved too.

best wishes,

Hoyt

------------------------------

Date: Mon, 28 Sep 1998 07:24:25
From: batwings@i-plus.net
Subject: Re: MC-Chassis Re: BMS Chassis stuff

At 12:44 AM 9/28/98 -0700, you wrote:
>
>
>other things. It is human nature to justify one's commitment, therefore the
>opinion of the maker or purchaser of an item is -always- suspect.

Not when it's based on solid experience. I can illustrate that out of my
own: I have been repairing them for 33 yeats, and have had quite a few
wobblers come my way. Luckily, because of my own proclivities for
precision, only one of my own scoots has ever done that (turned out to be a
broken rear MM, onto which the SA was hung). But of all those customers and
friends who came in with those complaints, all have gone out with no
wobble. Even in cases of front tires scrubbing huge S-shaped scuffs onto
the road, and tire-burnt fender inners, the things I do cure them. And out
of that, two things emerged: weak fork clamps and bad SA bngs are always
sufficient causes. Other things may contribute, but fixing those fixes it
all. I say, that gives me an edge on the discussion. 

>regards the experts and engineers testing - I expressed my desire to see
>their commentary on the top clamp seriously - I am very curious about this.
>And I'm probably wrong on this one - I'll admit it. But I'd like to see
>some non-anecdotal evidence.

The above is exactly that. If you want scientific analysis, look into the
SAE 1978 Symposium, on motorcycle dynamics, where lateral frame stiffness
and torsional fork stiffness are noted as being ultimates for good handling
bikes.

>I'm not trying to discredit anyone - I'm just stating that what people say
>in this case has not been what I've experienced. And I still don't
>understand what is wrong with the design.

I have never been over a BMW; it might take a bit more to fix than the two
main considerations above; after all the givens in them are basically OK
frames. That is said to not discount your own experience. But if a better
fork clamping arrangement isn't making a diff, then as one usually finds
tapered roller SA bngs a good design choice, then there is clearly a need
for frame mods too.

>Hoyt, I both agree and disagree with you completely. Yes, the BMW chassis
>is a flexible flyer. But my point is that is is a well balanced flexible
>flyer.

If the wheels don't stay aligned with each other within limits of the
suspension and steering, 'balanced' flex is not relevant; IE every little
excursion from the plan has potential disaster embedded in it because
timing of the forces traveling through the frame is essential.

 If you brace the swing arm ( a very good thing) and strengthen the
>front end (however you want to do it- I have a K1 front end on my Rbike,
>and a braced swingarm), then the frame just gets worse. 

Have to deal with that too.

>right will probably take replacing everything but the motor. Where do you
>stop?

When it stops. These things aren't what one calls a preferred mode of
travel. Aside from the scary aspects, there is incredible danger.

 My contention is that in some cases you're better off living with
>what you have, and maybe hiding a few faults with a steering damper, and a
>good shock. Oh - and most race bikes have steering dampers - does that mean
>that they are deficient? 

Yes. It's never ceased to amaze me how many bikes go out racing with
chassis totally insufficent for that. People spend $5000 on the mill and
don't even open the steering head or SA nose up to look. Many times, I find
racers in pits with things obviously loose (you can see the fretting powder
smeared around the bolt-heads), even under the safety wire. And owners are
surprised to have that pointed out to them. I once rode a fellows racer in
one heat and the brakes gave up on the third lap. When I got back in and
cracked the reservoir, there was brown sludge in it. Now, Ricky had been a
winner for several years and did have sense to get his big problem
(tank-slpper) in and I cured it. But he still didn't have a lock on racing,
did he? Not that these guys are as a rule unsophisticated; they are just
not aware of the dynamics involved in good handling. But, if you need to
spend big $$ on the motor, you obviously need to improve the chassis too.

>people say it works. Try to tweak the system you have before you get
>drastic. Check the steering head and swingarm bearings, make sure the
>springs are set up for you and your riding. 

Good advice!!

>think real hard before you buy the top clamp or the swingarm pivot: Is this
>going to make the bike better for me? would the money be better spent on a
>riding school?

Not quite, ask the experts. One cannot form opinions in a vacuum.

Best wishes,

Hoyt

------------------------------

End of MC-Chassis-Dgst V1 #771
******************************



MC-Chassis-Dgst       Monday, September 28 1998       Volume 01 : Number 772



 1. "Calvin Grandy"    Subj: Re: MC-Chassis Introduction
 2. Lauren        Subj: Re: MC-Chassis Introduction
 3. Lauren        Subj: Re: MC-Chassis Steering Dampers
 4. Lauren        Subj: Re: MC-Chassis BMW Chassis Mods
 5. yhakim@m5.sprynet.com                Subj: Re: MC-Chassis El Mirage Land speed
 6. briankk@aimnet.com (Brian Knowles)   Subj: Re: MC-Chassis Re: BMS Chassis stuff
 7. "Gary Beale"  Subj: Re: MC-Chassis Steering Dampers
 8. Lauren        Subj: Re: Fixing wobbles (was MC-Chassis Intro.)

----------------------------------------------------------------------

Date: Mon, 28 Sep 1998 08:59:47 -0400
From: "Calvin Grandy" 
Subject: Re: MC-Chassis Introduction

This is a multi-part message in MIME format.

- ------=_NextPart_000_01BDEABE.57AEC800
Content-Type: text/plain; charset=ISO-8859-1
Content-Transfer-Encoding: 7bit

I would like to leave the lawyers out of this list, and most everything
else.  If we choose a "risky" activity, whether cycles, flying, skiing,
caving, diving, or any, let us pick our own poison!  Litigation will
deprive us all from the choices we love to make.  Nobody wants to get hurt,
but nothing will prevent a fool from doing foolish things.  If the top
clamp on one model bothers you, don't buy it, or do something about it.  If
what you do is good, tell others and go into business.  The makers will get
the picture soon enough.  If we need compensation for our risk taking, we
need to become professionals not amateurs.

Regards

Calvin Grandy

P.S.  The racing at NHIS (Loudon) Sunday was quite good, with lots of
entry's in most classes.  I'm trying to break away today to get over for
the Vintage events. (two Hour ride)


- ----------
> From: batwings@i-plus.net
> To: mc-chassis-design@list.sirius.com
> Subject: Re: MC-Chassis Introduction
> Date: Monday, September 28, 1998 2:50 AM
> 
> At 07:49 PM 9/27/98 -0700, you wrote:
> >> 
> >Oh yes, get a lawyer involved.
> 
> Do I sense sarcasm? They may be a bit of an unpopular solution, but if
BMW
> made a bad design move and if it is a factor in crashes (which IMHO they
> did and it is), then anyone would be a fool not to take advantage of
> remediation. And if as in most cases there is a certain amount of
> argy-bargy involved, it's no skin off anyone's nose but BMW's collective
> nose, to have a lawyer involved too.
> 
> best wishes,
> 
> Hoyt

------------------------------

Date: Mon, 28 Sep 1998 08:45:20 -0700
From: Lauren 
Subject: Re: MC-Chassis Introduction

At 12:19 AM 9/26/98 , Hoyt wrote:
>
>If your bike uses that shitty little sheet-netal top 'clamp' your problem
>will go away when you replace it with something having 3 dimensions. BMW
>went through a huge lawsuit about a decade ago where it was alleged and
>proven that the fork is legally defective. I don't know if they recalled
>them, but they did pay a huge settlement. Maybe you should simply see a
>lawyer and let BMW pay for your mods.
>

Hoyt,

Thank you for your advice - but I don't believe my bike uses the top clamp
you mentioned. In fact I believe the GS top clamp is somewhat different
from other BMW R bikes of the same vintage.

As for a lawyer, well having known a lot of them and having worked in the
personal injury field (I wrote software for tracking the outcomes of spinal
injury trauma and therapy) - I don't believe I would have a case. You see I
could have prevented the accident in numerous ways:

1) I knew the bike had the wobbles at speed.
2) I was well over the speed limit when I hit the wet patch - by about
30-35 MPH.
3) I was thinking about other things and not paying attention to my riding
- - this is probably my worst sin - if I had been paying attention I probably
could have avoided the accident altogether even if all other factors had
been the same.

I don't like to sue anybody unless they are clearly at fault and I don't
think this was the case in this situation.

All that aside, thanks for the info on the top clamp - I will watch out for
BMWs with that clamp and keep the problem in mind.

FWIW,
LCB

'91 BMW R100GS - Geist der Freiheit
'94 Suzuki DR350ES

------------------------------

Date: Mon, 28 Sep 1998 08:50:51 -0700
From: Lauren 
Subject: Re: MC-Chassis Steering Dampers

At 02:18 PM 9/26/98 , Alan Lapp wrote:
>>While I am considering a steering damper, I would like to address the cause
>>as much as possible and not the symptoms.
>
>If you can't find an existing linear steering damper kit for your bike, and
>have to fabricate stuff, I'd recommend the Scotts or WER rotary steering
>damper.  I have a Scotts on my racebike, and my best friend has a WER on
>his.  They have nice action - some of the linear dampers seem to have an
>'over-center' feel i.e. the damping isn't uniform lock to lock.  They also
>have a very wide range of adjustment.
>
>However, I think that you're on the right track - a damper is merely a
>bandaid solution, and seeking to fix the cause of instability will
>ultimately lead to the superior solution.  I know racers who have their
>dampers set so stiff that they weave all over the pit area because they can
>barely steer at low speed, and I always wonder why they don't find out how
>to fix the problem.
>

Alan,

Thanks for the info - I will probably go with a steering damper as the last
thing I do. Not the last resort, but the last thing as I think it would
mask the other symptoms and I want to try to get to the root problem(s),
and even if I can't fix everything then at least I know what is going on.

I was leaning to the Scotts damper because coming mostly from the dirt bike
arena I am familiar with it. I have always wondered why the street bikes
tended mostly towards the linear dampers when the Scotts or WER seemed a
cleaner solution.

LCB

'91 BMW R100GS - Geist der Freiheit
'94 Suzuki DR350ES

------------------------------

Date: Mon, 28 Sep 1998 09:05:43 -0700
From: Lauren 
Subject: Re: MC-Chassis BMW Chassis Mods

At 01:44 AM 9/27/98 , Sam wrote:
>
>
>I''ve got a bit of experience modifying BMW frames - here's some things
>I've tried: 
>
>-put a stronger upper triple clamp on  the bike
>
>-Run braces from the steering head to the swingarm pivot
>
>-Gusset up all the little pieces around the Cyl head
>
>-Telefix fork brace
>
>-raise the engine in the frame 
>
>

Sam,

Thanks for the suggestions. I don't know about the upper triple clamp as I
don't think any aftermarket pieces are available for the GS - I would have
to have one made. I am not familiar with the Telefix fork brace - is this
the one that is a large tubular brace? I am under the impression that the
tubular brace I have seen will not work with my forks. 

I do not understand what "little pieces around the Cyl head" there are -
can you elucidate?

>
>The last mod was done by a guy in Seattle; I'll get his name if you want.
>Or for that matter, I've got a BMW R100 in a R65 chassis with all the above
>mods; just buy it from me.
>

I may go for the name - it might be a beneficial mod - although I think
part of the character I like about BMWs is the low center of gravity. Until
the bike gets out of shape it seems to go through corners more easily than
other bikes I have ridden. On the other hand it owuld be nice to have more
clearance off-road.

>Now, with all that said: Lauren, don't mess with your frame. The chassis is
>more than adequate for what you are talking about doing with the bike. The
>other suggestions about steering dampers are probably better investments.
>The Factory BMW P-D racebike used a near stock frame, FWIW. The only
>difference I know of is they modified the monoshock rear end into a twin
>shock.
>

I was under the impression that HPN had set the bikes up for BMW and that
they did more than just change the swing arms. 

First I want to get the bike into basically stock shape with new tires, new
rear shock, and new (Progressive) fork springs with new oil. Then from
there I will try to analyze what will be the best bang for the buck.

FWIW,
LCB
'91 BMW R100GS - Geist der Freiheit
'94 Suzuki DR350ES

------------------------------

Date: Mon, 28 Sep 1998 09:10:46 -0700
From: yhakim@m5.sprynet.com
Subject: Re: MC-Chassis El Mirage Land speed

On Mon, 28 Sep 1998, uranus  wrote:
>At 09:30 27/09/98 -0700, you wrote:
>>I tried using as much as 250 lbs. of ballast right in front of the rear tire
>>without much effect . For the record I had 115 lbs.. of ballast.
>>I know the aerodynamics of the bike aren't to good
>>any ideas????????????
>>Here is a current picture
>>http://www.geocities.com/MotorCity/Downs/4762/dyno2.JPG
>
>The GSX-R fairing is truly hopeless aerodynamically.  A dustbin fairing
>would be the one for lowest Cd, but look at e.g. Honda Super Blackbird to
>see some slightly more modern thinking.  A much more all-enveloping front
>mudguard would help loads, as would something to smooth the riders' back
>into the tail unit.  All of these would make a great difference at the
>speeds you're talking about, but perhaps you're restricted by some kind of
>silhouette regs.?
>
>Crosswind stability: I don't think I would want to push my luck on that . .
>. in fact I think I would insist on absolute dead air before trying to ride
>your bike at all!  
>
>Fairing generated lift:  realistically you must build some kind of lift
>measuring device (simple enough) and build up the speed progressively
>before going for it.  You mind need some kind of front wing/spoiler.
>
>  
>David T. (never been over 140mph) 

A GSXR 750 tail section may help, I was going to suggest drag bike body work, 
but looking at the stuff that airtech sells, it doesn't look THAT much better. 
If their is no sillhouette restrictions: During a Sport Rider UFO one of the 
teams shrouded a GSXR 1100 in some HD Daytona inspired front body work and a 
tail section that starts pretty high behind the rider in an attempt to match 
the riders back. I'll get pics scanned in a few days. Any way Airtech could 
probably make some more up, but it'd cost ya. The fastest bike in the test 
(233 MPH I think) used pretty stock looking front and a 750 tail. 
As another interesting note Blowin' in the wind just happens to be playing as 
I write this.
______________________________________________________
Yousuf (also never been over 140)
	
______________________________________________________  

------------------------------

Date: Mon, 28 Sep 1998 09:18:17 -0700
From: briankk@aimnet.com (Brian Knowles)
Subject: Re: MC-Chassis Re: BMS Chassis stuff

Hoyt posted:

(snip..)

>If you want scientific analysis, look into the
>SAE 1978 Symposium, on motorcycle dynamics, where lateral frame stiffness
>and torsional fork stiffness are noted as being ultimates for good handling
>bikes.
>
(more snippage..)

How?  Or perhaps where?  That's something I'd be interested in seeing my self.

Brian

------------------------------

Date: Mon, 28 Sep 1998 12:20:35 -0400
From: "Gary Beale" 
Subject: Re: MC-Chassis Steering Dampers

snip
>
>I was leaning to the Scotts damper because coming mostly from the dirt bike
>arena I am familiar with it. I have always wondered why the street bikes
>tended mostly towards the linear dampers when the Scotts or WER seemed a
>cleaner solution.
>
>LCB
>

It's probably something to do with the $150 purchase price, vs. around $300
for the rotary dampers.

Gary Beale
gbeale@atlanta.dg.com
>

------------------------------

Date: Mon, 28 Sep 1998 09:22:04 -0700
From: Lauren 
Subject: Re: Fixing wobbles (was MC-Chassis Intro.)

At 04:17 AM 9/27/98 , Scott wrote:

>Hello,
>David Doudna's reply included, " ... many other R100GS owners suggests his
>high-speed wobble problem will largely go away by replacing BMW's stock rear
>shock ... " and he mentions its flaws include leaking oil and improper
>damping.
>
>I ride an '84 Kawasaki GPz 750, that has the 'Uni-Trak' rear suspension. This
>machine has the ability to weave in a high speed sweeper. A popular "fix" is
>replace the stock rear single shock.
>Why-how does the rear suspension cause the bike to weave or wobble? I'm
>guessing it's unsettled, pogo-ing?
>

Scott,

My "experiments" before my accident (where I intentionally induced wobble
by moving the bars back and forth) lead me to believe that an oscillation
gets setup between the insufficient damping in the worn out rear shock, all
along the frame, and the front end. I think my accident resulted in a
severe case of this.

I am not exactly sure what happened after I had recovered from the slide
because that is when things really started to happen very fast. I think
either the bike suspension was upset enough that the oscillations started
or myself and the bike were now somewhat cross ways to the actual path I
was traveling. After I dumped the bike it wound up going to the right -
across all four lanes before settling on the shoulder. I wound up to the
right also - just not as far - I went across two lanes. Miraculously
niether I nor the bike were hit by following cars. I wish I had a video so
I could analyze what happened.

FWIW,
LCB
'91 BMW R100GS - Geist der Freiheit
'94 Suzuki DR350ES

------------------------------

End of MC-Chassis-Dgst V1 #772
******************************



MC-Chassis-Dgst       Monday, September 28 1998       Volume 01 : Number 773



 1. Lauren        Subj: Re: MC-Chassis BMW Chassis Mods
 2. Lauren        Subj: Re: MC-Chassis R100GS wobble
 3. briankk@aimnet.com (Brian Knowles)   Subj: Re: MC-Chassis Introduction
 4. SCOTTA336@aol.com                    Subj: MC-Chassis Bushings
 5. yhakim@m5.sprynet.com                Subj: MC-Chassis Wire vs cast spokes
 6. Lauren        Subj: Re: MC-Chassis Introduction
 7. "Sam Stoney"      Subj: MC-Chassis Re: Lauren's BMW stuff
 8. Douglas Lofgren  Subj: Re: MC-Chassis Re: BMS Chassis stuff
 9. batwings@i-plus.net                  Subj: Re: MC-Chassis Introduction
10. batwings@i-plus.net                  Subj: Re: MC-Chassis Introduction
11. batwings@i-plus.net                  Subj: MC-Chassis the 1978 SAE stuff

----------------------------------------------------------------------

Date: Mon, 28 Sep 1998 09:24:24 -0700
From: Lauren 
Subject: Re: MC-Chassis BMW Chassis Mods

At 12:06 AM 9/27/98 , you wrote:

>Sorry, it isn't and it does need work. IMHO the best improvements will be a
>proper top clamp and a SH-SA brace. If the bike doesn't have a deficiency
>in handling, a steering damper is not needed.
>

Hoyt,

I am unfamiliar with what a SH-SA brace is - could you explain what it is
for me, or point me to an explanation?

Thanks,
LCB
'91 BMW R100GS - Geist der Freiheit
'94 Suzuki DR350ES

------------------------------

Date: Mon, 28 Sep 1998 09:32:58 -0700
From: Lauren 
Subject: Re: MC-Chassis R100GS wobble

At 03:53 PM 9/27/98 , Andrew wrote:
>
>Lauren, I have a fair amount of experience with BMW R100GS handling;
I'mboth a
>currently certified tech and a GS owner. My approach to the high speed
wobbles
>that it sounds like your GS is having would be to first verify that all the
>suspension/ drive
>bearings are in spec then adjust your steering head bearing preload very
>carefully.
>      Bear in mind that having the preload too high is the
>usual cause of high speed wobbles. (I'm assuming SH bearings in reasonably
good
>shape)
> What I'm getting at is that the GS shouldn't wobble at those speeds if it's
>set up well.
>   One more thing-what are you running for tires?

Andrew,

I would admit that much of the wobble is probably coming from the fact that
my rear shock is worn out. I have only had the bike since June and intended
to replace the rear shock soon, but I was having too much fun riding the
bike to work on it.

I don't beleive the Steering head bearings are preloaded too much - if
anything they may not be preloaded enough as when the bike is on the center
stand the handlebars will easily fall to one side or another.

The tires I am running are worn Metzeler ME33/88 - not optimum.

I probably jumped the gun asking about frame mods before I have the bike
setup right (new rear shock, fork springs and new tires) - but I like to
gather info on such mods long before deciding what to do.

FWIW,
LCB
'91 BMW R100GS - Geist der Freiheit
'94 Suzuki DR350ES

------------------------------

Date: Mon, 28 Sep 1998 09:53:25 -0700
From: briankk@aimnet.com (Brian Knowles)
Subject: Re: MC-Chassis Introduction

Lauren posted:
>
>As for a lawyer, well having known a lot of them and having worked in the
>personal injury field (I wrote software for tracking the outcomes of spinal
>injury trauma and therapy) - I don't believe I would have a case. You see I
>could have prevented the accident in numerous ways:
>
>1) I knew the bike had the wobbles at speed.
>2) I was well over the speed limit when I hit the wet patch - by about
>30-35 MPH.
>3) I was thinking about other things and not paying attention to my riding
>- this is probably my worst sin - if I had been paying attention I probably
>could have avoided the accident altogether even if all other factors had
>been the same.

You are under the common mis-apprehension that engineering reality
influences the outcome of trials.  Take a look at the Ralph Nader/General
Motors/Corvair thing from the sixties, where it was shown that Naders
drawings/conclusions concerning the Corvair rear suspension wern't just
wrong, they were mechanically impossible, and Stirling Moss testified in
favor of the cars handeling.  GM lost anyway.

Brian

------------------------------

Date: Mon, 28 Sep 1998 13:00:57 EDT
From: SCOTTA336@aol.com
Subject: MC-Chassis Bushings

Hee-hee!  Another Pavlovian bell triggers Hoyt's bushing response.  

I'm fully convinced that the bushing fix is a valuable one for older designs.
I'm curious though, if there are any limitations to its application. I can't
really think why, since the load/bearing surface ratio on needle bearings are
clearly uglier than bushings.  

Still, when I look at the wacky way Honda's thrown bearings at my '94 CR 125
swingarm, I can barely repress a shudder.  In addition to twin needle
bearings, they're loaded axially through thrust needle bearings.  The RS 125
bearing structure is simpler, but needle bearings there, too.  Honda-san
frequently does things I don't understand, but he's not wrong a lot.  Still,
he does cut corners for ease of manufacturing.  Is this such an instance?

I mean, if I look at Doohan's 500, does he have bushings?  

So.  Are the pilot-reamed-in-place bronze (oilite?) bushings worth putting in
top-of-the-line GP and modern motocross bikes?  See, I've got this '99 on
order, just in time for the off-season & I know I'll be evaporating a bunch of
time on upgrades.


Wisdom receival mode engaged.

- -A

<< batwings@i-plus.net
 Subject: Re: Fixing wobbles (was MC-Chassis Intro.)
 
 At 07:17 AM 9/27/98 EDT, you wrote:
 >I ride an '84 Kawasaki GPz 750, that has the 'Uni-Trak' rear suspension.
This
 >machine has the ability to weave in a high speed sweeper.
 
 Just for the record, most 80s GPZs suffered from a swingarm which was small
 dia compared to the wgt and performance. I had a pal with a 550 which shook
 regularly. People who know my prefs will probably begin gagging about right
 now, but replacing the SA bngs which were shot with good snug bronze units
 made it better. For bigger bikes and/or racing, I would suggest using a
 stronger or reinforced SA.
  >>

------------------------------

Date: Mon, 28 Sep 1998 10:05:15 -0700
From: yhakim@m5.sprynet.com
Subject: MC-Chassis Wire vs cast spokes

I was looking thru the Japanese mag "clubman" and they had some shots 
of "Motard" bikes. They all used cast streetbike wheels as opposed to 
the wire wheels laced with wider rims that I've previously seen on 
converted dirt bikes. Is there any benifit to staying with wire wheels 
(if you don't plan on going off road)?
______________________________________________________
Yousuf
	
______________________________________________________  

------------------------------

Date: Mon, 28 Sep 1998 10:39:10 -0700
From: Lauren 
Subject: Re: MC-Chassis Introduction

At 09:53 AM 9/28/98 , Brian wrote:
>
>You are under the common mis-apprehension that engineering reality
>influences the outcome of trials.  Take a look at the Ralph Nader/General
>Motors/Corvair thing from the sixties, where it was shown that Naders
>drawings/conclusions concerning the Corvair rear suspension wern't just
>wrong, they were mechanically impossible, and Stirling Moss testified in
>favor of the cars handeling.  GM lost anyway.
>

Brian,

You are only half right - my assertion that I did not have a case was in
part based on engineering reality. But as I have been involved in setting
up the evidence for expert testimony in personal injury cases, I also know
that *if properly presented* it is the objective plain facts that usually
win out. We are not talking about political situations like Nader's
grandstanding, or the OJ Simpson case here. Either way, I still could not
convince myself to bring suit against someone if I knew I was in the wrong,
nor would I be able to lie under oath to cover up the facts of the situation.

FWIW,
LCB
'91 BMW R100GS - Geist der Freiheit
'94 Suzuki DR350ES

 

------------------------------

Date: Mon, 28 Sep 1998 14:28:15 -0700
From: "Sam Stoney" 
Subject: MC-Chassis Re: Lauren's BMW stuff

Lauren said:

> Thanks for the suggestions. I don't know about the upper triple clamp as
I
> don't think any aftermarket pieces are available for the GS - I would
have
> to have one made. I am not familiar with the Telefix fork brace - is this
> the one that is a large tubular brace? I am under the impression that the
> tubular brace I have seen will not work with my forks. 
> 

It's an earlier design - I doubt that there is one for your bike. I really
don't know what's available for it. I differ to Andrew Fairbank on this
one.


> I do not understand what "little pieces around the Cyl head" there are -
> can you elucidate?


There are a lot of spaces around the -steering- head that can be stiffened
with gussetting. Take off the gas tank and look - you'll see what I mean.
Then again, I think BMW has started gussetting them - maybe they are done
on your bike.


> 
> I was under the impression that HPN had set the bikes up for BMW and that
> they did more than just change the swing arms. 

I looked long and hard at the GS P-D at the Guggenheim. I was shocked how
stock it looked. I'm certain more was done, but nothing drastic, as far as
I could see....


> 
> First I want to get the bike into basically stock shape with new tires,
new
> rear shock, and new (Progressive) fork springs with new oil. Then from
> there I will try to analyze what will be the best bang for the buck.


Wise man. Think about talking to a suspension guy re spring rates and the
such, before buying the springs. There's a guy up there who works under the
name "jet city suspension" or something like that. Seattle Cycle Center
will have his name I bet. We does a lot of racetech installations for them.
He has setup experience with both RR and dirt.


Sam

------------------------------

Date: Mon, 28 Sep 1998 14:26:58 -0700
From: Douglas Lofgren 
Subject: Re: MC-Chassis Re: BMS Chassis stuff

Sam Stoney wrote:

> 
> I'm not trying to discredit anyone - I'm just stating that what people say
> in this case has not been what I've experienced. And I still don't
> understand what is wrong with the design.

   Even though I've replaced mine with a reworked bottom clamp, I agree
with Sam. But, I haven't done any scientific testing.
   My opinion, was (when I worked on them regularly) that the top clamp
is dependent on the proper torque on the fork top nuts, for torsional
rigidity. Other than adding torsional rigidity (to the entire fork
system)(when properly torqued)and locating the top of the tubes relative
to the stem, it serves no other purpose other than mounting the
handlebars.

   Those older twins were very sensitive to all of the chassis
adjustments, especially, steering head torque. When we raced one, a
complete, stock, chassis adjustment procedure was what was needed to get
it to behave, even with a steering damper.
   Doug Lofgren

------------------------------

Date: Mon, 28 Sep 1998 13:39:30
From: batwings@i-plus.net
Subject: Re: MC-Chassis Introduction

At 08:59 AM 9/28/98 -0400, you wrote:
>but nothing will prevent a fool from doing foolish things.  If the top
>clamp on one model bothers you, don't buy it, or do something about it.  


I think Calvin is at least the second one to mistake the intentions I had
in mind ...  many times the problems don't show up until after sale,and
just finding out the facts is often quite hard. There may be a recall,
maybe not. In either case, and especially if there is, a pro may be helpful
to find out. Perhaps properly prodded BMW will do something about it. But
unless they are pretty atpical, it will be much harder for the individual
to do that. That doesn't necessarily any of it mean a lawsuit, and anyway,
Calvin himself advocates something being done, above.

Best wishes

Hoyt
---------------------------

Date: Mon, 28 Sep 1998 13:45:12
From: batwings@i-plus.net
Subject: Re: MC-Chassis Introduction

At 08:45 AM 9/28/98 -0700, you wrote:
>1) I knew the bike had the wobbles at speed.

Not an issue; the bike is required to be suitable for it's intended purpose.

>2) I was well over the speed limit when I hit the wet patch - by about
>30-35 MPH.

Hard to overcome

>3) I was thinking about other things and not paying attention to my riding
>- this is probably my worst sin - 

No doubt.

I come at this from perspective of expert witness, so to me seeking advice
or information from lawyer is a natural. Of course I didn't mean to advise
anyone to just go out and sue, just to use whatever means required to get
the facts. All that isn't relevant if your top clamp isn't the one subject
to that other suit. 

best wishes,

Hoyt



------------------------------

Date: Mon, 28 Sep 1998 13:54:28
From: batwings@i-plus.net
Subject: MC-Chassis the 1978 SAE stuff

It should be available from SAE. They have a web site where you can search
for their pubs. It is also in my university library and may be in many
more. It is best described as a series of papers presenteed at one of their
symposiums, and bound for publication; I believe thay have only a few every
year and that was the most recent on cycles. 

A lot of the guys who presented, not perhaps too oddly, were British. Most
of them were hard core experimenters as well as theoreticians. Some of the
dynamical analysis is pretty stiff; frame system instabilites are hard it
seems to analyze, probably because there is so much to mathematically
define between the points (contact patches) where the forces are fed in. To
me, the practical materials were a lot more valuable.

Best wishes,

Hoyt

At 09:18 AM 9/28/98 -0700, you wrote:
>Hoyt posted:
>
>(snip..)
>
>>If you want scientific analysis, look into the
>>SAE 1978 Symposium, on motorcycle dynamics, where lateral frame stiffness
>>and torsional fork stiffness are noted as being ultimates for good handling
>>bikes.
>>
>(more snippage..)
>
>How?  Or perhaps where?  That's something I'd be interested in seeing my
self.
>
>Brian


------------------------------

End of MC-Chassis-Dgst V1 #773
******************************



MC-Chassis-Dgst       Monday, September 28 1998       Volume 01 : Number 774



 1. batwings@i-plus.net                  Subj: Re: MC-Chassis BMW Chassis Mods
 2. batwings@i-plus.net                  Subj: Re: MC-Chassis Introduction
 3. batwings@i-plus.net                  Subj: Re: MC-Chassis Re: BMS Chassis stuff
 4. Jerry Wills          Subj: Re: MC-Chassis El Mirage Land speed record
 5. "Calvin Grandy"    Subj: MC-Chassis Re: Metal Matrix Composite material
 6. "Griffiths, Duncan"  Subj: Re: MC-Chassis Steering Dampers
 7. "Peter Snell"        Subj: MC-Chassis Single sided swingarm revisited
 8. Alan Lapp  Subj: Re: MC-Chassis Steering Dampers
 9. yhakim@m5.sprynet.com                Subj: Re: MC-Chassis Steering Dampers
10. "Michael Moore"   Subj: Re: MC-Chassis El Mirage Land speed

----------------------------------------------------------------------

Date: Mon, 28 Sep 1998 14:01:11
From: batwings@i-plus.net
Subject: Re: MC-Chassis BMW Chassis Mods

At 09:24 AM 9/28/98 -0700, you wrote:
>I am unfamiliar with what a SH-SA brace is - could you explain what it is
>for me, or point me to an explanation?

Yes, you know: its a brace between steering head (SH) and swingarm pivot
(SA). I see them used on lots of street bikes converted to racers and it
seems to me that as they are directly in line with a major load they must
be of some value. Sorry about the abbreviations confusing you. 

I have been led to understand there are buyable braces out there for BMW.
The value of these would depend on how much triangulation is introduced to
the frame. Moving the motor may also change the stiffness of the frame by
bracing things better, and maybe those two could be made to work together.

Best wishes,

Hoyt

------------------------------

Date: Mon, 28 Sep 1998 15:16:57
From: batwings@i-plus.net
Subject: Re: MC-Chassis Introduction

At 09:53 AM 9/28/98 -0700, you wrote:
>You are under the common mis-apprehension that engineering reality
>influences the outcome of trials.  

As someone who has seen this first hand, I can tell you that it often does.
My own testimony has been decisive in several suits and my opinions in
deposition have affected several more. Courts are bound by law to give
proper observance to scientific knowledge, which is why guys like me who
have done the work and know the facts get involved. (And just to forestall
anyone condemning me for being a hazard to the sport by encouraging
lawsuits: I take cases because my expertise is valuable in finding truth,
which knows no master, and I work for about as many defendants as plaintiffs.)

>Take a look at the Ralph Nader/General
>Motors/Corvair thing from the sixties, where it was shown that Naders
>drawings/conclusions concerning the Corvair rear suspension wern't just
>wrong, they were mechanically impossible, and Stirling Moss testified in
>favor of the cars handeling. 

The Corvair used a form of suspension which for decades was known to
produce rear-wheel steering due to the inevitable camber increase from
cornering. That is precisely the same effect that makes motorcycles steer,
but with the front wheel instead. VW knew this and limited it by
restricting the downward motion, but even so they did still react hard now
and then, have seen it from behind one myself and even been in one while
reacting! All that is why performance types racing those used considerable
decambering and even drop-straps for absolute limits. GM may have known but
didn't restrict it enough; the result was cars which did go out of control
in certain circumstances. I was in one of them myself, with five others,
when the driver took a corner slightly fast. Before he could react, it had
jacked ALL the way up, spun and stalled. Since it was a convertable, I
consider myself very lucky it didn't go over, and I think probably only the
weight of the extra people keep the camber-steering within bounds and
prevented that.

A complicating factor in all this was that GM made the front tire inflation
pressure 13 PSI to increase front end slip angle and keep the ends in line,
while the rear was about 26-28 PSI. Now, can anyone tell me what pressure
to carry in the spare tire? People just didn't check this while changing on
the road, and it caused more problems if the wrong pressure went on either
end.

I didn't follow the trial but if Stirling Moss testified specifically that
60-64 Vair was always safe, he is either a bad driver or had never driven
one! He would have been perfectly correct about other forms of swingarm
autos, however; my own 74 Mercedes and many others used SA and that one in
particular is one of the best handling cars on wheels. I used to dive off
the interstates at 65-70, and just let it slide around the exit ramp. You
could accelerate, brake and steer it as well while all four tires were
howling as at any other time, and the steering wheel hardly reacted. Try
that in an early Vair. Later Vairs went to essentially the same rear ends
as Vettes, and they had no problems.

I also don't know what drawings and conclusions Nadar presented and like
many others I also regard him as a bit of a flake. That didn't however make
the accidents un-happen or the testimony of the victims vanish. As for it
being 'shown' he was wrong, well, that's what juries are for and in the
long run they're pretty hard to fool.

Best regards,

Hoyt
-------------------------

Date: Mon, 28 Sep 1998 15:51:40
From: batwings@i-plus.net
Subject: Re: MC-Chassis Re: BMS Chassis stuff

At 02:26 PM 9/28/98 -0700, you wrote:
>   My opinion, was (when I worked on them regularly) that the top clamp
>Other than adding torsional rigidity (to the entire fork
>system)(when properly torqued)and locating the top of the tubes relative
>to the stem, it serves no other purpose other than mounting the
>handlebars.

Those are all of the functions of any top clamp. The issue of course is
whether the Beemer item is as good at holding its fair share of that torque
on the tubes, as would be a thicker clamp pinch-bolted to them. It's MHO
that that the BMW top can simply never measure up to the latter in that
respect, as a design method. 

That is because no threaded fastener is secure against loads that tend to
rotate it in alternate directions. Even with very long fasteners (that
preserve a lot of preload with some loosening), the above is usually
sufficient to eventually un-load them, and the BMW fork caps aren't long
enough to even have that advantage.

best regards,

Hoyt

------------------------------

Date: 28 Sep 1998 13:27:00 -0700
From: Jerry Wills 
Subject: Re: MC-Chassis El Mirage Land speed record

"Rick"  writes:

> 
> I tried using as much as 250 lbs. of ballast right in front of the rear tire
> without much effect . For the record I had 115 lbs.. of ballast.
> I know the aerodynamics of the bike aren't to good
> any ideas????????????

at that speed a "interesting shaped" belly pan, might provide the ground
effect downforce without adding much to the aero problem you already have.

Oh no did I suggest ground effect bikes? :^) maybe for straight lines.

			Jerry Wills 
USC/Information Sciences Institute  (USC/ISI)  SoCal (310) 822-1511 x 236
I'll have enough POWER when I can spin the tires at the end of the straight!
89 FJ DERSLYR,93 GTS1000  DoD#500 KotF(Flag)       Mark Donahue, about 917's
90's cowboys, ride iron horses, and punch Deer!!!
You done violated Physics, BOY!    Assume the position..... (Rider 5/92)

------------------------------

Date: Mon, 28 Sep 1998 17:12:50 -0400
From: "Calvin Grandy" 
Subject: MC-Chassis Re: Metal Matrix Composite material



A quick look at the monthly "Machine Design" turns up an article regarding
metal matrix composites.  A Vacuum/pressure casting into a "matrix"
generally ceramic.
These are the materials recently subject to comments on this list.

	Specs for MAIO-55/295 material (55%Al2O3 in Alu.295 matrix)

	Elastic Modulus		167GPa
	Yield Strength		379MPa	(55ksi)
	Thermal Conductivity	88.5 W/m x K
	Coefficient of thermal exp	13.3 X 10e6/K
	Density			2.97 Kg/m cubed	(.125 lb/in. cube)

	Ductile cast iron would allow 215 MPa Yield and 7.1 Kg/ m cubed.

Internally ribbed Brake rotors and Ferrari Formula 1 motor con rods are
displayed.
Rod in forged steel  485 grams, in MMC 190 grams.
Will wonders never cease?

Contact Metal Matrix Composites Inc. in Waltham Mass. to place your order.

Regards

Calvin Grandy


------------------------------

Date: Mon, 28 Sep 1998 14:08 -0800
From: "Griffiths, Duncan" 
Subject: Re: MC-Chassis Steering Dampers

Most, if not all, of us regard the steering damper as a band-aid to fix   
something wrong elsewhere in the handling department.  Would you also   
agree that it serves a purpose on generally good-handling bikes when they   
experience an unusual or extreme situation/loading that starts an   
oscillation?

Yamaha's recent TZ250's have massively rigid chassis and suspension, but   
would shake their head without the steering damper connected.  A fellow   
racer had the mounting bracket break during the recent Pikes Peak   
national and the bike was literally unrideable.  Is this a case of a   
minimal amount of trail to get quick steering, and letting the damper   
handle the instability?

Any thoughts on the preferable damping characteristics for steering?   
 I'll be looking at getting a new damper this winter and there are a lot   
of choices.  Hyperpro sells one that has progressively greater damping   
with higher shaft speed.  There are a couple that are gas charged, which   
should help with cavitation.  The standard TZ damper works fairly well,   
and it's just a adjustable damping model.  One of the rotary damper   
models I looked at has a setting for overall damping level, but also   
increases the level of damping the further off-center the steering is.   
 Too many choices.

Cheers,

Duncan
(I go at least 140mph twice a lap at Willow Springs)

------------------------------

Date: Mon, 28 Sep 1998 17:29:37 -0400
From: "Peter Snell" 
Subject: MC-Chassis Single sided swingarm revisited

A while back we were discussing a comment about how much the eccentric
chain adjuster on a SSSA would affect ride height. Well, I spent the
weekend working with an RS250, and the chain adjustment required to
change from 16/40 to 15/39 yielded a 8 mm difference(!),in rear ride
height, measured at the rear axle. This is a pretty significant change
with these bikes, and necessitated a correction with the ride height
adjuster.
- -- 
__
Pete Snell
Royal Military College       
Kingston, Ontario,      | We dance round in a ring and suppose,
Canada.                 | But the Secret sits in the middle and knows.
Snell-p@rmc.ca    	|      Robert Frost (1874-1963)

------------------------------

Date: Mon, 28 Sep 1998 17:36:01 +0100
From: Alan Lapp 
Subject: Re: MC-Chassis Steering Dampers

>I was leaning to the Scotts damper because coming mostly from the dirt bike
>arena I am familiar with it. I have always wondered why the street bikes
>tended mostly towards the linear dampers when the Scotts or WER seemed a
>cleaner solution.

In the 'good old days' of unfaired bikes, the linear dampers were easy to
mount.  With the plastification of bikes, they've become more and more
dificult to mount.  However, I can't recall a rotary damper on the market
before the late '80s.

There are 2 popular positions for rotary dampers: in front of the lower
triple clamp, and above the top triple clamp.  Both have drawbacks - with
the lower mount, often, fairing brackets or headlight assy's must be
relocated or modified.  With the upper mount, a suitable (i.e. really
stiff) bracket to the frame must be made, and it's in a rather unsightly
position.

FYI, the WER damper is significantly less expensive than the Scotts.

Al
level_5_ltd@earthlink.net

------------------------------

Date: Mon, 28 Sep 1998 15:13:32 -0700
From: yhakim@m5.sprynet.com
Subject: Re: MC-Chassis Steering Dampers

WOW! I must admit I'm a little suprised that the 250 would be so unridable. A 
94 APRILIA RSV250 has 21 deg (although it's adjustable) and 3.30 inches of 
trail. An all new singin' dancin' R1 has 24 deg and 3.6 inches. Now as I 
understand it trail is the figure of interest. The 250's is only a little 
less and weighs a LOT less. So it should be okay. Maybe his riding style has 
something to do with it. 



On Mon, 28 Sep 1998, "Griffiths, Duncan"  wrote:
>Most, if not all, of us regard the steering damper as a band-aid to fix   
>something wrong elsewhere in the handling department.  Would you also   
>agree that it serves a purpose on generally good-handling bikes when they   
>experience an unusual or extreme situation/loading that starts an   
>oscillation?
>
>Yamaha's recent TZ250's have massively rigid chassis and suspension, but   
>would shake their head without the steering damper connected.  A fellow   
>racer had the mounting bracket break during the recent Pikes Peak   
>national and the bike was literally unrideable.  Is this a case of a   
>minimal amount of trail to get quick steering, and letting the damper   
>handle the instability?
>
>Any thoughts on the preferable damping characteristics for steering?   

>Cheers,
>
>Duncan
>(I go at least 140mph twice a lap at Willow Springs)
>
______________________________________________________
Yousuf
	
______________________________________________________  

------------------------------

Date: Mon, 28 Sep 1998 16:57:11 -0800
From: "Michael Moore" 
Subject: Re: MC-Chassis El Mirage Land speed

> A GSXR 750 tail section may help, I was going to suggest drag bike body work, 
> but looking at the stuff that airtech sells, it doesn't look THAT much better. 
> If their is no sillhouette restrictions: During a Sport Rider UFO one of the 
> teams shrouded a GSXR 1100 in some HD Daytona inspired front body work and a 
> tail section that starts pretty high behind the rider in an attempt to match 
> the riders back. I'll get pics scanned in a few days. Any way Airtech could 
> probably make some more up, but it'd cost ya. The fastest bike in the test 
> (233 MPH I think) used pretty stock looking front and a 750 tail. 

Or you could order a big seat that was designed strictly from aero 
needs and not styling from Hanson Racing Technology.  Check out the 
pictures of it on the graphics page under Craig Hanson's bikes - Marc 
Roux's XL250 roadracer is the one you want to look at.  A matching 
H-D long track fairing would be a good idea too.

Cheers,
Michael


------------------------------

End of MC-Chassis-Dgst V1 #774
******************************



MC-Chassis-Dgst      Tuesday, September 29 1998      Volume 01 : Number 775



 1. "Michael Moore"   Subj: Re: MC-Chassis Bushings
 2. "Michael Moore"   Subj: Re: MC-Chassis Re: BMS Chassis stuff
 3. papazit@juno.com (Chris L Johnson)   Subj: Re: MC-Chassis Introduction
 4. "Griffiths, Duncan"  Subj: Re: MC-Chassis Steering Dampers
 5. "Michael Moore"   Subj: MC-Chassis FS: Trick Alazzurra in the San Francisco area
 6. "Frank Camillieri"  Subj: MC-Chassis BMW frames
 7. batwings@i-plus.net                  Subj: Re: MC-Chassis Steering Dampers
 8. batwings@i-plus.net                  Subj: Re: MC-Chassis Bushings

----------------------------------------------------------------------

Date: Mon, 28 Sep 1998 16:57:11 -0800
From: "Michael Moore" 
Subject: Re: MC-Chassis Bushings

> Are the pilot-reamed-in-place bronze (oilite?) bushings worth putting in

Hello Scott,

I think you'd be better off with a sturdier bearing bronze, like SAE 
660.  The oillite is, as far as I know (which isn't as far as I think 
some times), a lower duty material.  Besides, you'll be greasing the 
bushings often enough to not need the bushing to store lubricant 
within its structure.

A least your Honda didn't come with Metalastic bushings in the swing 
arm as many BSAs did.  Of course, if it had you'd have no doubt that 
the bronze bushings would be better.

Needle bearings seem like an odd thing to use in a dirt bike.  
Bushings would be more tolerant to the (inevitable?) ingestion of 
dirt.

Cheers,
Michael


------------------------------

Date: Mon, 28 Sep 1998 16:57:10 -0800
From: "Michael Moore" 
Subject: Re: MC-Chassis Re: BMS Chassis stuff

> How?  Or perhaps where?  That's something I'd be interested in seeing my self.
> 
Hello Brian,

>From my tech book bibliography page:

AIAA SECOND SYMPOSIUM AERODYNAMICS OF SPORTS AND COMPETITION
AUTOMOBILES    ISBN 0-87938-028-4
  American Institute of Aeronautics and Astronautics, Western     
    Periodicals Co.

MOTORCYCLE DYNAMICS AND RIDER CONTROL   ISBN (none)
  Society of Automotive Engineers #SP-428
 
2 for the price of none (listings that is)

Cheers,
Michael


------------------------------

Date: Mon, 28 Sep 1998 20:06:50 -0400
From: papazit@juno.com (Chris L Johnson)
Subject: Re: MC-Chassis Introduction

>You are under the common mis-apprehension that engineering reality
>influences the outcome of trials.  Take a look at the Ralph 
>Nader/General Motors/Corvair thing from the sixties...GM lost anyway.
>
>Brian

It's really simple: there is no logic to it and it's not about right and
wrong or engineering integrity or anything.  It's about deep pockets. 
The reality distortion field effect about lawyers is directly
proportional to the proximity to deep pockets.  It's a simple violation
of the tenth commandment where you shall not desire your neighbor's
stuff.

Chris (CJ) Johnson, Director of Engineering,
College Park Industries, Inc.     http://www.college-park.com
(810) 294-7950 (at CPI), (616) 664-4173 (home office)
papazit@juno.com
Scorpa 250/Gas-Gas 160/Fantic 305/Three 650 Yamahas

------------------------------

Date: Mon, 28 Sep 1998 17:39 -0800
From: "Griffiths, Duncan" 
Subject: Re: MC-Chassis Steering Dampers

I'll check the trail figure and wheelbase when I get home for comparison   
purposes.

I've experienced the same headshake/tankslapper effect when my damper   
blew a seal.  As this was in Sunday morning practice, we just filled it   
with oil before the race.  After a few laps, it started getting very   
exciting again, so it's just a characteristic of the bike.

Duncan
===========
From: yhakim@m5.sprynet.com

WOW! I must admit I'm a little suprised that the 250 would be so   
unridable. A
94 APRILIA RSV250 has 21 deg (although it's adjustable) and 3.30 inches   
of
trail. An all new singin' dancin' R1 has 24 deg and 3.6 inches. Now as I
understand it trail is the figure of interest. The 250's is only a little   

less and weighs a LOT less. So it should be okay. Maybe his riding style   
has
something to do with it.

On Mon, 28 Sep 1998, "Griffiths, Duncan"    
wrote:
>Most, if not all, of us regard the steering damper as a band-aid to fix   
    

>something wrong elsewhere in the handling department.  Would you also
>agree that it serves a purpose on generally good-handling bikes when   
they
>experience an unusual or extreme situation/loading that starts an
>oscillation?
>
>Yamaha's recent TZ250's have massively rigid chassis and suspension, but   
    

>would shake their head without the steering damper connected.  A fellow   
    

>racer had the mounting bracket break during the recent Pikes Peak
>national and the bike was literally unrideable.  Is this a case of a
>minimal amount of trail to get quick steering, and letting the damper
>handle the instability?

------------------------------

Date: Mon, 28 Sep 1998 19:34:42 -0800
From: "Michael Moore" 
Subject: MC-Chassis FS: Trick Alazzurra in the San Francisco area

Yes friends, a twice in a lifetime chance is knocking at your door
again.

Robert Allen, who bought my modified Alazzurra from me several years
ago, contacted me last week to tell me that the press of work over the
next few years was going to keep him from doing anything with the
bike.  His landlord was threatening to have the bike towed by the end
of the week (he'd had the wheels off to be powdercoated and it looked
like an abandoned bike to the landlord) if he didn't move it first.

I've now got the bike in my storage unit and the signed title in hand.

After he bought the bike Robert had the wheels powdercoated a nice
sort of greenish gold (or at least that is what they looked like in
the darkling gloom) and installed a full set of new wheel bearings
(special sizes only available from your friendly local Ducati dealer
for a princely sum) along with a set of new Metzlers.  Otherwise, it
is largely as it was when he bought it from me in August 1996.

Truth in advertising statement:

The bike has been sitting for some months, and though the relay 
clicks it won't turn over on the button, indicating a low battery or a
bit of corrosion has crept in on some terminal(s).  When I made a new
wiring harness I got a bit fuddled toward the end of a very long day
and the headlights need to have a small jumper wire moved to turn them
on/off, though the dimmer switch works fine.

Robert bought the bike as a project - intending to tidy up the loose
electrical/cosmetic ends that I never got around to doing.  You can
read about all the modifications I did to the bike (and see photos)
at:

http://www.eurospares.com/forsale.htm

As I recall, Robert paid me $2400 for the bike and has obviously put
another $500 or so into the wheels.  While this is a bit of a distress
sale in that Robert won't be able to use it and I have plenty of other
projects already (besides, I've already been there and done that) I've
got enough room in the storage unit to let it sit for a reasonable
offer to come along.  So no, it won't be sold for $900 (and I've
already got someone interested in it for significantly more than
that), but on the other hand the price will be nice enough to allow
you to have a tricked up bike suitable for club 650 Twins or canyon
carving with some money left over to tidy things up.  

Mostly, it needs some TLC and elbow grease to finish the painting etc.

So if you are interested drop Robert a note at:

Robert Allen
rja@sun.com (days)
wolverines@worldnet.att.net (eves)

Keep in mind that I'm heading off to Spain the last three weeks of
October, so I won't be around for you to have access to the bike
during that period.

Cheers,
Michael


------------------------------

Date: Tue, 29 Sep 1998 00:02:36 -0400
From: "Frank Camillieri" 
Subject: MC-Chassis BMW frames

I've been reading the comments on BMW handling and I guess some BMW 
racers don't know about these problems. We have a couple of guys in the 
USCRA on them that don't seem to have any trouble winning. Tim Courts rides 
a 500 with a frame that doesn't look very modified and it doesn't appear to be 
any faster than other 500s. I was looking it over today and it has a diagonal 
tube welded under the transmission and some gussets at the SH but no other 
bracing. Also he is still using the stock top fork clamp. The front end is lifted a 
bit and he still grinds the rocker covers pretty good. At NHIS, where good riding 
is more important than speed, it is hard to keep him in sight.  

While on the subject of forks I will tell you about mine. I am using Ceriani 
35mm and haven't got around to making a fork brace. While going through tech 
inspection today Kevin C. held my wheel between his knees and asked where I 
would like my wheel to point, while twisting the clipons back and forth. The only 
problem I find is a bit of front wheel chatter while braking hard into corners. 
Once you let go of the brake it's fine. Next season I will have a brace and let 
you know if it made a difference. 

I'm going to take this machine apart and measure it to find out how straight it 
is. I've had the SA off and  know it is twisted .060". I'm interested because I 
built this frame 30 years ago and it handles great. It would be funny if it's not 
straight at all and still handles OK. I don't remember how many times the guy I 
built it for crashed , but I've crashed it twice this year. One front down tube was 
twisted years ago from a major engine blow up where the rod tried to take out 
the motor mount. As I remember he beat it back with a large plastic mallet. 
There's still a dent in it from that beating. 
 

Frank Camillieri
Chester, NH

------------------------------

Date: Mon, 28 Sep 1998 20:45:25
From: batwings@i-plus.net
Subject: Re: MC-Chassis Steering Dampers

At 02:08 PM 9/28/98 -0800, you wrote:
>Most, if not all, of us regard the steering damper as a band-aid to fix   
>something wrong elsewhere in the handling department.  Would you also   
>agree that it serves a purpose on generally good-handling bikes when they   
>experience an unusual or extreme situation/loading that starts an   
>oscillation?

Without a doubt. The guys who said the rotaries were probably better were
also correct; for one thing due to angulation the linear ones change ratio.
>
>Yamaha's recent TZ250's have massively rigid chassis and suspension, but   
>would shake their head without the steering damper connected.  A fellow   
>racer had the mounting bracket break during the recent Pikes Peak   
>national and the bike was literally unrideable.  Is this a case of a   
>minimal amount of trail to get quick steering, and letting the damper   
>handle the instability?

Much of that is due to wide tires. Your hotter scoots are also essentially
hi-Q systems and due to their complexity you have to fine tune things on
them just as you would in electronics circuits. Another way to look at them
is as sytems with many degrees of freedom, most of those small. But since
they are there and are dynamically active, they usually fulfill the overall
description of a chaotic system. In 'ordinary' riding, this system is
stable in one mode, essentially a strange attractor for the ordinary track
behaviors. In this instance it's OK to think of attractors as rubber model
gravity wells containing the system dynamics; the behavior of the system
bounces around a trajectory that defines the well, but never goes as high
as the upper limit though it spends a lot of time near it if you're riding
hard. Let some of the small DF get bigger (your sudden impact drives some
of them harder) and the system then does what other chaotic systems do: the
trajectory bounces over the edge of the well and finds another attractor
that contains entirely new system dynamics, usually ones you didn't want
(like a highly dissipative limit cycle), or it may wander the slopes and
ridges around and between all that, and may even finally go back to the
ordinary well, lucky you, but you'll need to sponge the leathers, eh? The
damper prevents that by dissipating energy from the system's smaller
dynamics, hence the traj never bounces over the edge of the ordinary well.
See J. Gliek's CHAOS for deeper explanations. 

What the steering damper is probably doing in some of these examples is
taking up slack in the remainder of the chassis, and hence placing dampers
directly on it would probably do much the same thing. For example, one
thing twin dampers do that monos don't, is prevent torsional oscillation in
the SA, because each sits directly on one end of the axle where each is
individually responsive to it. Torsional deflections in the SA definitely
cause steering head twitches, go figure. It's up to you where to put these
on your frame, but good bets would be parallel to members which had the
biggest length deflections and square to the bending. That's probably what
the flexi-frame people think they're doing, but they still have to explain
how they dissipate pretty big bursts of energy in materials with Young's
modulus high enough for frames. Maybe there is hope for this in rheological
engineering of materials.

>Any thoughts on the preferable damping characteristics for steering? 

Velocity sensitive, yes?  You want to compromise between ordinary effort at
ordinary steering speeds, but you want it to go super dissapative to
prevent sudden whippings of bars; they're the ones which take your
attention off the line you want. IOW, your damping should be critical
(absorbs all the extra energy in one cycle) at all frequencies.

> Hyperpro sells one that has progressively greater damping   
>with higher shaft speed. 

Yeah, like that.
 
>increases the level of damping the further off-center the steering is.   
> Too many choices.

Could be the same thing, but also probably helpful since faster impacts
take you farther. 

Best regards,

Hoyt


------------------------------

Date: Mon, 28 Sep 1998 21:01:50
From: batwings@i-plus.net
Subject: Re: MC-Chassis Bushings

At 01:00 PM 9/28/98 EDT, you wrote:
>I'm fully convinced that the bushing fix is a valuable one for older designs.
>I'm curious though, if there are any limitations to its application. I can't
>really think why, since the load/bearing surface ratio on needle bearings are
>clearly uglier than bushings.  

It's better in every way. The bushings are immune to lack of grease and
moisture ... they may show scuffing but will never stick to or damage steel
inners and if they're merely wet with lube they last forever. Nerdle
rollers go to pieces with the slightest moisture, which is attracted
directly to the capillary spaces between the rollers and races. Race
curvature is high, hence so is stress hence life is low. If they had larger
elements it would be better, but even tapered rollers are sensitive to that
to a degree.

>In addition to twin needle
>bearings, 

Get rid of the retainers, crowd in extra rollers everywhere.

>I mean, if I look at Doohan's 500, does he have bushings?  

Not mine anyway.
>
>So.  Are the pilot-reamed-in-place bronze (oilite?) bushings worth putting in
>top-of-the-line GP and modern motocross bikes?  See, I've got this '99 on
>order, just in time for the off-season & I know I'll be evaporating a
bunch of
>time on upgrades.

That's how I got started doing them, in my own MX bikes. Worked fine for
me. I've done it in woods racing for years too.

Best regards,

Hoyt

------------------------------

End of MC-Chassis-Dgst V1 #775
******************************



MC-Chassis-Dgst      Tuesday, September 29 1998      Volume 01 : Number 776



 1. batwings@i-plus.net                  Subj: Re: MC-Chassis BMW frames
 2. Allen G  Subj: MC-Chassis delurk alert, RZ500 measurements
 3. bc180@freenet.carleton.ca (Peter Alan Engelbert) Subj: Re: MC-Chassis BMW frames
 4. Lauren        Subj: Re: MC-Chassis BMW Chassis Mods
 5. "Gary Beale"  Subj: Re: MC-Chassis Single sided swingarm revisited
 6. "Frank Camillieri"  Subj: MC-Chassis Kurt's Rennsport
 7. Alan Lapp  Subj: Re: MC-Chassis Kurt's Rennsport
 8. jpanstr@ravenet.com (John Anstreicher) Subj: Re: MC-Chassis FS: Trick Alazzurra in the San Francisco area
 9. "Frank Camillieri"  Subj: MC-Chassis Rennsports
10. Stephen Watson      Subj: Re: MC-Chassis-Dgst V1 #775

----------------------------------------------------------------------

Date: Tue, 29 Sep 1998 07:25:58
From: batwings@i-plus.net
Subject: Re: MC-Chassis BMW frames

At 12:02 AM 9/29/98 -0400, you wrote:
>I've been reading the comments on BMW handling and I guess some BMW 
>racers don't know about these problems. We have a couple of guys in the 
>USCRA on them that don't seem to have any trouble winning.

What does he race against?

I have no ax to grind for BMW handling qualities, but enough people have
pointed out enough deficiencies to make me look for the usual causes. Those
would include bad fork clamping and unbraced framing, which both do seem to
appear on them (or at least the former did once).

>it has a diagonal 
>tube welded under the transmission and some gussets at the SH but no other 
>bracing. 

Sounds like quite enough to make a change in the frame stiffness.

> The only 
>problem I find is a bit of front wheel chatter while braking hard into
corners. 
>Once you let go of the brake it's fine. 

Chatter seems to be related to fork stiffness, maybe more to axle stiffness.

Always great to hear from an old-schooler with lots of experience.

Best wishes,

Hoyt

------------------------------

Date: Tue, 29 Sep 1998 10:06:39 -0400
From: Allen G 
Subject: MC-Chassis delurk alert, RZ500 measurements



Hi all,

I've been lurking on this list for long while, via the digests;

Intro:  I've been street riding about ten years, 100,000 + miles, all
sport bikes.  My first bike was an RZ350.  I've raced and am looking to
get back into it when $$$ permits.  Currently, the only bike in the
garage is an RZ500 parts-pile.  I've printed out many of the discussions
on chassis dynamics - (gyroscopics is key!!); my knowledge is mainly
suspension setup, and parts-replacement top-end work.  

RZ500:   What I'm doing is mounting 1997 GSXR600 front-end and back-end
suspension parts on it.  The front is no problem, but the back requires
measurements of parts I don't have.  I plan to take this bike to the
track, so I want to get the alignment right.
    
Questions:  Does anybody here have one?   Anybody know the distance from
the inner face of the left swingarm @ the axle, to the center of the
rear wheel?  Also, the inner face of the left swingarm @ the axle, to
the center of the rear sprocket?  I have the stock swingarm, but no
wheel or cush drive.  I think these two measurements will be enough to
properly locate the GSXR swingarm at the pivot, and correct the
cushdrive or sprocket positions such that the rear wheel is in stock
alignment with the front end.

TIA 

Allen G 
Atlanta GA USA

------------------------------

Date: Tue, 29 Sep 1998 10:33:20 -0400 (EDT)
From: bc180@freenet.carleton.ca (Peter Alan Engelbert)
Subject: Re: MC-Chassis BMW frames

>Frank wrote
>I've been reading the comments on BMW handling and I guess some BMW 
>racers don't know about these problems. We have a couple of guys in the 
>USCRA on them that don't seem to have any trouble winning. Tim Courts rides 
>a 500 with a frame that doesn't look very modified and it doesn't appear to be 
>any faster than other 500s. I was looking it over today and it has a diagonal 
>tube welded under the transmission and some gussets at the SH but no other 
>bracing. Also he is still using the stock top fork clamp. The front end is lifted a 
>bit and he still grinds the rocker covers pretty good. At NHIS, where good riding 
>is more important than speed, it is hard to keep him in sight.  
>

Tim's bike also has the engine raised and moved forward in the frame. I
had a good go at Kurt Liebman (sp?) on his Rennsport 500 at Mosport in August.
Now there's a serious BMW. 

- --
Peter Engelbert: bc180@Freenet.Carleton.CA  or engelbp@mczcr.gov.on.ca
Vintage Road Racing: it's never too late to have a happy childhood. 

------------------------------

Date: Tue, 29 Sep 1998 08:42:47 -0700
From: Lauren 
Subject: Re: MC-Chassis BMW Chassis Mods

At 07:01 AM 9/28/98 , batwings@i-plus.net wrote:

>I have been led to understand there are buyable braces out there for BMW.
>The value of these would depend on how much triangulation is introduced to
>the frame. Moving the motor may also change the stiffness of the frame by
>bracing things better, and maybe those two could be made to work together.
>

The one brace that I have been able to find from CC Products would not seem
to me to offer much triangulation. It spans the parallelogram that
encompasses the engine. But this is one of the few arrangements that would
be workable without making the engine components harder to service.

They also offer a a swing arm brace but this is for older dual shock BMWs.
Like wise the Sh reinforcement is for different frames, but not mine.

One person I have had correspondence with in Sweden stated that HPN
modified the frame on his bike along the following lines:

Start quote.
**********

1:The pivotpoint of the rear swingarm. Plates are welded to the sides of the
mainframecage in the area where the bearings for the rear swingarm are
mounted.

2: The steeringhead, a profile is welded to the large frametube leading
rearwards from the steeringhead.

3: Below the steeringhead, the standardplates are doubled in thickness. If
they are replaced or if they are simple doubled, I can't say.

4: A plate is added at the rear end of the main frametube, where it splits
into the parts that reaches down to the pivotpoint for the swingarm.

5: A plate is welded on both sides at the rear end of the maintube,
connecting the maintube to the tube that reaches forwards to the
steeringhead.

A few more profiles are added, but they do not act as reinforcements.

**************

His web page showing the reinforcements is at 


http://www.zebra.fh-weingarten.de/~possi/hpnpg.html

He also states that these mods make "a world of difference". But I am loath
to send my bike halfway around the world for these mods.

FWIW,
LCB

'91 BMW R100GS - Geist der Freiheit
'94 Suzuki DR350ES

------------------------------

Date: Tue, 29 Sep 1998 11:24:55 -0400
From: "Gary Beale" 
Subject: Re: MC-Chassis Single sided swingarm revisited

Hi Peter.

Somebody's point was that, with the appropriate length chain, large
adjustments should never be necessary.  If you had a spare chain that was a
couple links shorter, would you have been able to adjust the proper slack
without undue ride height changes?

(Leaving aside the issue of breaking, installing, and carrying spare chains
of different lengths!)

Gary Beale
gbeale@atlanta.dg.com

>A while back we were discussing a comment about how much the eccentric
>chain adjuster on a SSSA would affect ride height. Well, I spent the
>weekend working with an RS250, and the chain adjustment required to
>change from 16/40 to 15/39 yielded a 8 mm difference(!),in rear ride
>height, measured at the rear axle. This is a pretty significant change
>with these bikes, and necessitated a correction with the ride height
>adjuster.
>--
>__
>Pete Snell
>Royal Military College
>Kingston, Ontario,      | We dance round in a ring and suppose,
>Canada.                 | But the Secret sits in the middle and knows.
>Snell-p@rmc.ca    |      Robert Frost (1874-1963)
>

------------------------------

Date: Tue, 29 Sep 1998 12:45:18 -0400
From: "Frank Camillieri" 
Subject: MC-Chassis Kurt's Rennsport

> I  had a good go at Kurt Liebman (sp?) on his Rennsport 500 at Mosport in August.
> Now there's a serious BMW. 
> 
Peter,
I had great times in the 60's racing with Kurt on his Rennsport. I was riding 
Reno Leoni's 350 Desmo Ducatis and crashed more than once trying to keep 
ahead of him. About 10 years ago I saw Reno at Louden and introduced him to 
my son. The first thing Reno said to him was " Your father used to crash my 
bikes". I think he was still mad about it. Kurt's still one of the fast guys.



Frank Camillieri
Chester, NH

------------------------------

Date: Tue, 29 Sep 1998 13:28:26 +0100
From: Alan Lapp 
Subject: Re: MC-Chassis Kurt's Rennsport

>> I  had a good go at Kurt Liebman (sp?) on his Rennsport 500 at Mosport
>>in August.
>> Now there's a serious BMW.
>>
>Peter,
>I had great times in the 60's racing with Kurt on his Rennsport. I was riding
>Reno Leoni's 350 Desmo Ducatis and crashed more than once trying to keep
>ahead of him. About 10 years ago I saw Reno at Louden and introduced him to
>my son. The first thing Reno said to him was " Your father used to crash my
>bikes". I think he was still mad about it. Kurt's still one of the fast guys.

Frank: what a great story!

I recall from probably 10 years ago, that there was a man in Frederick MD
who was building new Rennsports from factory drawings. He was hiring out
the casting, but build almost everything else in his shop.  It was
fascinating to me, and always wanted to visit his shop but never did.

Al
level_5_ltd@earthlink.net

------------------------------

Date: Tue, 29 Sep 1998 13:46:53 -0400
From: jpanstr@ravenet.com (John Anstreicher)
Subject: Re: MC-Chassis FS: Trick Alazzurra in the San Francisco area

Hi Michael:

    Glad to hear you got your AZ back.
The analog clock Cagiva put in the dash has the undesirable
effect of flattening a battery in a few weeks, but I suspect you
had already jettinsoned it.  I replaced mine with a VDO oil temp
gauge running off switched V+ and made up a new drain plug
with the sender in it.  It shows it takes a while for the 99 barrels
of oil in a Pantah engine to warm up.
    Michael, just curious; what cams are in the AZ?  Have you
ever experimented with hot Pantah cams before?  I'm wondering
because I have a set of 'Montjuich' camshafts I never installed
and am looking to talk to someone who has set up experience
and riding time with these.

    See ya.                                                          John

- ----------

> The bike has been sitting for some months, and though the relay 
> clicks it won't turn over on the button, indicating a low battery or a
> bit of corrosion has crept in on some terminal(s).  When I made a new
> wiring harness I got a bit fuddled toward the end of a very long day
> and the headlights need to have a small jumper wire moved to turn them
> on/off, though the dimmer switch works fine.

------------------------------

Date: Tue, 29 Sep 1998 15:35:42 -0400
From: "Frank Camillieri" 
Subject: MC-Chassis Rennsports

Al,
The only Rennsport I've ever seen is Kurt's and his father built it. If I remember 
right the barrels were tipped up a bit, but it's been at least 10 years since I last 
saw it. I was away from bikes for a number of years so I must have missed 
hearing about the other guy.

Frank Camillieri
Chester, NH

------------------------------

Date: Wed, 30 Sep 1998 08:35:23 +1200
From: Stephen Watson 
Subject: Re: MC-Chassis-Dgst V1 #775

Just a quick note to say thanks to the people that gave me a hand with
the calculations concerning front wheel spindle.  I checked my units as
I have been knowen to mix em up , no that was fine , but I had failed to
take into account of the spacers this improved matters   alot.   A very
quick check reveals a deflection of 0.4mm with a big fatty -me- and
153kg of bike all outbraking Mick Doohan into the hairpin (I wish !!)

Cheers for the help
Stephen  ( Watsons@Ibm.net )

MC-Chassis-Dgst wrote:


------------------------------

End of MC-Chassis-Dgst V1 #776
******************************



MC-Chassis-Dgst      Tuesday, September 29 1998      Volume 01 : Number 777



 1. "Thimjon, Dean CPT - 25IDL"  Subj: RE: MC-Chassis FS: Trick Alazzurra in the San Francisco area
 2. "Griffiths, Duncan"  Subj: Re: MC-Chassis Steering Dampers
 3. "Sam Stoney"      Subj: MC-Chassis BMW Frames
 4. "Tony Foale"        Subj: MC-Chassis Re: BMW frames
 5. "Tony Foale"        Subj: MC-Chassis Re: Chain adjustment
 6. bsags@isat.com (David Kath)          Subj: MC-Chassis Suzuki motor
 7. "Tony Foale"        Subj: MC-Chassis Re: Proper BMs.
 8. yhakim@m5.sprynet.com                Subj: Re: MC-Chassis Steering Dampers
 9. "Kelvin Blair"      Subj: Re: MC-Chassis-Dgst SA Bushes
10. "Ray or Emily Brooks"  Subj: Re: MC-Chassis delurk alert, RZ500 measurements
11. Johnayleng@aol.com                   Subj: MC-Chassis rake,trail and wheelbase stuff
12. "Frank Camillieri"  Subj: MC-Chassis Re: Head shake
13. "Michael Moore"   Subj: Re: MC-Chassis rake,trail and wheelbase stuff

----------------------------------------------------------------------

Date: Tue, 29 Sep 1998 11:02:41 -1000
From: "Thimjon, Dean CPT - 25IDL" 
Subject: RE: MC-Chassis FS: Trick Alazzurra in the San Francisco area

Michael,
	I am intersted in getting a copy of the book "The Racing
Motorcycle: a technical guide for constructors".  How much and where do
I send the money?
Dean

------------------------------

Date: Tue, 29 Sep 1998 14:04 -0800
From: "Griffiths, Duncan" 
Subject: Re: MC-Chassis Steering Dampers

The TZ figures are 22.5 degrees rake, 81.5mm (3.21") trail, and 53"   
wheelbase.  It's a bit steeper than that with the rear ride height   
adjusted up a bit.  The rake shouldn't affect stability.  Almost every   
race bike I've seen has a steering damper, so I'm sure it's just the fact   
that we're pushing the limits of all the components as Hoyt discussed (in   
a somewhat abstract manner).

Is the RSV the road or race bike?  Would the greater mass of street-duty   
wheels tend to damp the oscillations compared to race-spec aluminium or   
magnesium wheels?  I know the race Aprilia's are using dampers and I   
would bet they have the same problems without the damper.

Duncan
=================
From: yhakim@m5.sprynet.com
WOW! I must admit I'm a little suprised that the 250 would be so   
unridable. A
94 APRILIA RSV250 has 21 deg (although it's adjustable) and 3.30 inches   
of
trail. An all new singin' dancin' R1 has 24 deg and 3.6 inches. Now as I
understand it trail is the figure of interest. The 250's is only a little   

less and weighs a LOT less. So it should be okay. Maybe his riding style   
has
something to do with it.

------------------------------

Date: Tue, 29 Sep 1998 17:48:13 -0700
From: "Sam Stoney" 
Subject: MC-Chassis BMW Frames

From: batwings@i-plus.net
Subject: Re: MC-Chassis BMW frames

At 12:02 AM 9/29/98 -0400, Frankwrote:
>I've been reading the comments on BMW handling and I guess some BMW 
>racers don't know about these problems. We have a couple of guys in the 
>USCRA on them that don't seem to have any trouble winning.

What does he race against?


Tim Courts and Tom Verville are both just plain fast, and have NHIS wired.
They run in the USCRA vintage classes and consistantly run with the fastest
AHRMS guys when AHRMA comes up there. I'm moving back there, and I cant
wait to race them again.

Last time I raced my BMW I won open twins in the last Hoquiam, WA street
race. 2nd, I think, in BEARS, if I remember correctly. The competition was
Ducatis, Buells, Hondas and the such.

Like I said, they are not stiff, but they are predictable. And predictable
is more important than stiff in racing.


Sam

****************************************************************************
**********
BTW - Can we all watch how much of the original message we CC in our
replies????
****************************************************************************
********

------------------------------

Date: Tue, 29 Sep 1998 18:24:58 +0200
From: "Tony Foale" 
Subject: MC-Chassis Re: BMW frames

Ref. the recent thread on the above.

The main "weakness" of  the BMW series /5 /6 /7 frames is in the area of the
SA pivot mounting.  Side loads on the rear wheel will tend to make the
upright tubes holding said pivot move fore and aft.
This can largely be prevented by mounting a bracing tube on each side.
These tubes can be attached to high up on the front down tubes or to the
underside at the front of the mini backbone.  At the rear I mount them above
the SA pivot.  Some others put the rear mountings below the SA pivot  (see
p182 of the Clymer manual 500-1000cc twins 1970-1979, October 1979) but the
under side is better supported by the bottom rails  which are tied to the
rigid crankcase anyway.
These tubes obviously need to be detachable for engine removal etc. and so
the detail of the fixing can be very important to the success of the mod.
I don't like the simple drilled flat brackets combined with a flatened tube
end that I've seen.  I've used mating bosses with one counter-sunk at 45deg
and drilled and tapped, and the mating one turned with a male 45deg, the
other side counter bored for the head of an allen bolt.  These are mounted
at right angles to the bracing tube and so the taper takes the main load and
the bolt simply holds them together, as long as the bolt is tight then there
is no slop, and I've never known the bolts to come loose.

Another though less important frame mod. is to put a short bracing tube from
the rear of the top of the head stock back on to the backbone, this will
reduce some distortion under braking.
Other than that the frame loop needs no other bracing, afterall it's heavy
enough as is.

The above refers only to the main frame loop, and is not meant to indicate
that the other factors mentioned by others, such as suspension units,
correct maintanence etc. are not important.  You'll get no worthwhile
results from such mods. unless all the other bits are in good nick.

On machines with earlier engines there is one mod that I've found very
useful to help general handling as well as gear changing, and that is to
reduce the flywheel mass as much as possible, you just can't go too light.
Later engines had a different flywheel which was about as light as they
could go from the factory.  Probably the easiest way to go is to use the
later flywheel assembly.  It saves a lot of machining, drilling and
balancing work.  Those BMW flywheels were made of tough stuff.

Tony Foale

Espaņa / Spain
http://www.ctv.es/USERS/Softtech/motos

------------------------------

Date: Wed, 30 Sep 1998 00:48:44 +0200
From: "Tony Foale" 
Subject: MC-Chassis Re: Chain adjustment

Gary said;

<<
Somebody's point was that, with the appropriate length chain, large
adjustments should never be necessary.  If you had a spare chain that was a
couple links shorter, would you have been able to adjust the proper slack
without undue ride height changes?
>>

Well I did make that point, of course a large range of adjustment can be
more convenient for sprocket changes, but don't think that you get anything
for nothing.  Even if you have a truly linear movement which gives no ride
height adjustment you will still get a wheel base change.  I also made the
point that wheelbase adjustment should be done from a viewpoint other than
sprocket selection.
Convenient or not, it is best to keep the range of chain adjustment as small
as will do THAT job and keep secondary effects to a minimum, then you can
choose or adjust ride height and wheel base according to other needs.
Talking of sprocket changes indicates that you're talking about racing,
unless it's something that needs to be done during a race then convenience
should take second place to performance.  If that means changing a chain
with a sprocket then surely that's no big deal.

Tony Foale

Espaņa / Spain
http://www.ctv.es/USERS/Softtech/motos

------------------------------

Date: Tue, 29 Sep 1998 15:46:17 -0700
From: bsags@isat.com (David Kath)
Subject: MC-Chassis Suzuki motor

Gents... Pardon the non-chassis content please... A friend is looking
for a good Suzuki GSXR1100 engine complete for a racer project. Any
sources would be appreciated. TIA dave - NV

------------------------------

Date: Wed, 30 Sep 1998 00:56:08 +0200
From: "Tony Foale" 
Subject: MC-Chassis Re: Proper BMs.

Frank said:

<<
The only Rennsport I've ever seen is Kurt's and his father built it. If I
remember
right the barrels were tipped up a bit,
>>

There was a guy in the States years ago with the same surname who certainly
tilted the barrels on rennsports,  it seems likely that he was the father
that you mention.
If I remember correctly he used a five degree tilt, but I'm not sure if that
was each side making it a 170deg included angle or whether the 5deg was the
total making 175deg.

Tony Foale

Espaņa / Spain
http://www.ctv.es/USERS/Softtech/motos

------------------------------

Date: Tue, 29 Sep 1998 16:07:04 -0700
From: yhakim@m5.sprynet.com
Subject: Re: MC-Chassis Steering Dampers

On Tue, 29 Sep 1998, "Griffiths, Duncan"  wrote:
>The TZ figures are 22.5 degrees rake, 81.5mm (3.21") trail, and 53"   
>wheelbase.  It's a bit steeper than that with the rear ride height   
>adjusted up a bit.  The rake shouldn't affect stability.  Almost every   
>race bike I've seen has a steering damper, so I'm sure it's just the fact   
>that we're pushing the limits of all the components as Hoyt discussed (in   
>a somewhat abstract manner).
>
>Is the RSV the road or race bike?  Would the greater mass of street-duty   
>wheels tend to damp the oscillations compared to race-spec aluminium or   
>magnesium wheels?  I know the race Aprilia's are using dampers and I   
>would bet they have the same problems without the damper.
>
The measurements were off Biaggi's bike. I always thought steering dampeners 
were more insurance than necessity. I'm just trying to think where the head 
shake is coming from. The streetbikes that are thought to need a dampner have 
always been those with short wheelbase and trail combined with a high power 
to weight; Loft the front wheel and the front gets nice and loose. You are 
probably right about pushing the limits though, I'm just unclear as to what 
forces are causing the shakes.

______________________________________________________
Yousuf
	
______________________________________________________  

------------------------------

Date: Wed, 30 Sep 1998 07:33:11 +0800
From: "Kelvin Blair" 
Subject: Re: MC-Chassis-Dgst SA Bushes

Just to add to the SA bush discussion.  When I was an apprentice Toolmaker
I was riding a Z1000J (Kwaka).  One of the sales lines was that it had
"Needle Roller Swing Arm Bearings" I always thought needle roller bearings
were for things that rotated continuously.  This was confirmed the first
time I took the SA off, they are a totally absurd thing to use in that
application.  I am still confused as to why MC manufacturers utilise them
and advertise the fact.  
To cure the Z1000 I made up Hardened and ground steel bushes and sleeves
(just to be one better than bronze bushes) OK when you have a Toolroom at
your disposal, that combined with a little SA stiffening and SH bracing
made it ride pretty good.
Cheers
Kelvin

------------------------------

Date: Tue, 29 Sep 1998 20:52:19 -0400
From: "Ray or Emily Brooks" 
Subject: Re: MC-Chassis delurk alert, RZ500 measurements

Allen,

  Buzz's Psycle in Chamblee probably has a GSXR you could measure. They are
in the phone book.

Ray
Lawrenceville

- ----------
> From: Allen G 
> To: mc-chassis-design@list.sirius.com
> Subject: MC-Chassis delurk alert, RZ500 measurements
> Date: Tuesday, September 29, 1998 10:06 AM
> 
> 
> 
> Hi all,
> 
> I've been lurking on this list for long while, via the digests;
> 
> Intro:  I've been street riding about ten years, 100,000 + miles, all
> sport bikes.  My first bike was an RZ350.  I've raced and am looking to
> get back into it when $$$ permits.  Currently, the only bike in the
> garage is an RZ500 parts-pile.  I've printed out many of the discussions
> on chassis dynamics - (gyroscopics is key!!); my knowledge is mainly
> suspension setup, and parts-replacement top-end work.  
> 
> RZ500:   What I'm doing is mounting 1997 GSXR600 front-end and back-end
> suspension parts on it.  The front is no problem, but the back requires
> measurements of parts I don't have.  I plan to take this bike to the
> track, so I want to get the alignment right.
>     
> Questions:  Does anybody here have one?   Anybody know the distance from
> the inner face of the left swingarm @ the axle, to the center of the
> rear wheel?  Also, the inner face of the left swingarm @ the axle, to
> the center of the rear sprocket?  I have the stock swingarm, but no
> wheel or cush drive.  I think these two measurements will be enough to
> properly locate the GSXR swingarm at the pivot, and correct the
> cushdrive or sprocket positions such that the rear wheel is in stock
> alignment with the front end.
> 
> TIA 
> 
> Allen G 
> Atlanta GA USA

------------------------------

Date: Tue, 29 Sep 1998 21:22:21 EDT
From: Johnayleng@aol.com
Subject: MC-Chassis rake,trail and wheelbase stuff

  I'm new to chassis development and understanding. (ie:DUH)! 

  I just read an interesting article in Superbike magazine (Sept. 98) which of
course agreed with you on the importance (or lack of) rake has to steering
"quickness."  So would I be correct in my train of thought that the reduced
rake angles of newer bikes is to shorten the wheelbase and transfer the weight
bias forward? Also the article stated that less rake places more stress on the
frame during "bump" and "braking." Is this the reason older bikes used more
rake?

John Aylor NM ( newbe to spaghetti physics)

------------------------------

Date: Tue, 29 Sep 1998 22:20:06 -0400
From: "Frank Camillieri" 
Subject: MC-Chassis Re: Head shake

Is the head shake we are talking about something that is dangerous or just 
disconcerting? I once raced a Triumph that was bored out to 800cc in a stock 
frame and it would shake very hard coming out of corners at full throttle. It was 
bad enough to scare riders following me, but it never felt dangerous.  It had 
wide flat track bars and was rather fun to ride. It probably would have been 
frightening with clipons. Any other bike I rode only seemed to shake a little 
when the front got light exiting a corner. I had heard of riders being thrown off 
from speed wobbles but never saw it happen. A few races ago a rider I know 
said he got into a wobble that caused him to crash. I asked him about it and he 
said it happened when he dumped the  clutch coming out of a corner. I don't 
know what else he could have expected. Maybe wide bars are the thing to try 
when dampers don't work.

Frank Camillieri
Chester, NH

------------------------------

Date: Tue, 29 Sep 1998 20:01:50 -0800
From: "Michael Moore" 
Subject: Re: MC-Chassis rake,trail and wheelbase stuff

> bias forward? Also the article stated that less rake places more stress on the
> frame during "bump" and "braking." Is this the reason older bikes used more
> rake?

Hello John,

Less rake will place more stress on the frame if the front end is 
attached to a steering head.  The steeper the rake the farther 
forward the steering head has to go, stretching out the frame.

Also, I'd think that the forks might have more leverage on the 
steering head the steeper the rake as the braking force would be fed 
in at something more closely approaching a right angle letting the 
force mainly twist the steering head instead of trying to push it 
backwards as well.

Cheers,
Michael

------------------------------

End of MC-Chassis-Dgst V1 #777
******************************



MC-Chassis-Dgst     Wednesday, September 30 1998     Volume 01 : Number 778



 1. briankk@aimnet.com (Brian Knowles)   Subj: Re: MC-Chassis Introduction
 2. David Weinshenker   Subj: MC-Chassis metal casting question
 3. briankk@aimnet.com (Brian Knowles)   Subj: Re: MC-Chassis Introduction
 4. briankk@aimnet.com (Brian Knowles)   Subj: Re: MC-Chassis metal casting question
 5. Johnayleng@aol.com                   Subj: Re: MC-Chassis metal casting question
 6. Johnayleng@aol.com                   Subj: Re: MC-Chassis-Dgst SA Bushes
 7. "Tony Foale"        Subj: MC-Chassis Re: Steering dampers
 8. Duncan Griffiths  Subj: MC-Chassis Re: Head shake
 9. Julian Bond  Subj: Re: MC-Chassis Re: Steering dampers
10. batwings@i-plus.net                  Subj: Re: MC-Chassis-Dgst SA Bushes
11. batwings@i-plus.net                  Subj: Re: MC-Chassis Re: Head shake
12. batwings@i-plus.net                  Subj: Re: MC-Chassis Introduction

----------------------------------------------------------------------

Date: Tue, 29 Sep 1998 20:02:29 -0700
From: briankk@aimnet.com (Brian Knowles)
Subject: Re: MC-Chassis Introduction

(Snip..)
 I was in one of them myself, with five others,
>when the driver took a corner slightly fast. Before he could react, it had
>jacked ALL the way up, spun and stalled. Since it was a convert able, I
>consider myself very lucky it didn't go over, and I think probably only the
>weight of the extra people keep the camber-steering within bounds and
>prevented that.
>
>A complicating factor in all this was that GM made the front tire inflation
>pressure 13 PSI to increase front end slip angle and keep the ends in line,
>while the rear was about 26-28 PSI. Now, can anyone tell me what pressure
>to carry in the spare tire?

30 psi?

>People just didn't check this while changing on
>the road, and it caused more problems if the wrong pressure went on either
>end.
>
>I didn't follow the trial but if Stirling Moss testified specifically that
>60-64 Vair was always safe, he is either a bad driver or had never driven
>one! He would have been perfectly correct about other forms of swingarm
>autos, however; my own 74 Mercedes and many others used SA and that one in
>particular is one of the best handling cars on wheels. I used to dive off
>the interstates at 65-70, and just let it slide around the exit ramp. You
>could accelerate, brake and steer it as well while all four tires were
>howling as at any other time, and the steering wheel hardly reacted. Try
>that in an early Vair. Later Vairs went to essentially the same rear ends
>as Vettes, and they had no problems.
>
Moss said that driven properly the Corvair wasn't either dangerous or
"unconventional".  The problem was that "driven properly" meant that the
driver knew how and didn't try braking in the middle of the curve, 'cause
like the Porsche and VW, the car had trail-throttle over steer and would
swap ends if the driver lifted in the turns.

Porsche fought the same battle again in the '70s when some club racer lent
his girlfriend his 930 for errands and she  spun out big time, taking a
chunk of traffic with her.  In the ensuing suit, her lawyers alleged that
the car was inherently unstable, Porsche responded that it was designed
that way, for drivers who had a clue...  I don't remember the outcome of
that one, but the front engined (924/944/etc.) series makes me think they
may have lost.

You about have me convinced about the swing-arm bushing conversion.  How
much would it cost to convert my '88 Honda NX?  What about the headstock?

Brian

p.s.  I still haven't found out what rods/pistons are used with the 266
Buick engine, but I will.
bk

------------------------------

Date: Tue, 29 Sep 1998 20:02:27 -0700
From: David Weinshenker 
Subject: MC-Chassis metal casting question

Can anyone recommend a web site with good general reference
information on Casting (especially sand casting aluminum alloy)
and Pattern-Making?

- -dave w

------------------------------

Date: Tue, 29 Sep 1998 20:26:37 -0700
From: briankk@aimnet.com (Brian Knowles)
Subject: Re: MC-Chassis Introduction

Oops!  Sorry folk, that last one was supposed to go to Hoyt direct, not the
list.  Sorry for the bandwidth..

Brian

------------------------------

Date: Tue, 29 Sep 1998 20:28:25 -0700
From: briankk@aimnet.com (Brian Knowles)
Subject: Re: MC-Chassis metal casting question

>Can anyone recommend a web site with good general reference
>information on Casting (especially sand casting aluminum alloy)
>and Pattern-Making?
>
>-dave w

http://www.keynet.net/~lindsay/  Has what you need..

Brian

------------------------------

Date: Tue, 29 Sep 1998 23:45:14 EDT
From: Johnayleng@aol.com
Subject: Re: MC-Chassis metal casting question

In a message dated 9/29/98 9:14:43 PM Mountain Daylight Time, daze39@grin.net
writes:

> Can anyone recommend a web site with good general reference
>  information on Casting (especially sand casting aluminum alloy)
>  and Pattern-Making?
>  

   Dave,

 I don't know of and web sites, but I have a book on it that is very
understandable.

  The title is: The Complete handbook of Sand Castings
by C.W.Ammen   about $16.00 US

John Aylor NM

------------------------------

Date: Wed, 30 Sep 1998 00:34:10 EDT
From: Johnayleng@aol.com
Subject: Re: MC-Chassis-Dgst SA Bushes

In a message dated 9/29/98 6:11:59 PM Mountain Daylight Time, nwk@bigpond.com
writes:

> To cure the Z1000 I made up Hardened and ground steel bushes and sleeves
>  (just to be one better than bronze bushes) OK when you have a Toolroom at
>  your disposal, that combined with a little SA stiffening and SH bracing
>  made it ride pretty good.


  I never messed with my SA bearings on my J (or GPZ, both 81's). I did
convert to a 16" front wheel. Raced the Aspen 6 hour in 82,83. We could easily
stuff the 500 singles even in the tighter corners. 

John Aylor NM

------------------------------

Date: Wed, 30 Sep 1998 09:08:08 +0200
From: "Tony Foale" 
Subject: MC-Chassis Re: Steering dampers

Yousuf said, about the need for steering dampers:

>>I'm just unclear as to what
>>forces are causing the shakes.

Whilst various deficiencies in the machine give rise to wobbles and shakes,
and these have been well enough discussed here before, there are still
plenty of other reasons for the bike wanting to rip the handle bars out of
the rider's hands.
For example, with today's very wide tyres there is plenty of opportunity for
bumps and stones to contact the tyre considerably off centre, this obviously
will produce a torque about the steering axis.
This is but one example,  don't assume that a damper is only useful to mask
the effects of an oscillation it can be valuable in reducing the unwanted
steering response to a whole range of external impulses.  This can have
beneficial effects on rider fatigue and also in bike handling, unwanted
steering motions will result in unwanted roll motions too.
Contrary to oft repeated "wisdom" a steering damper is not just to mask
inadequate chassis features.  In fact in some cases a damper can worsen such
inadequacies.


Tony Foale

Espaņa / Spain
http://www.ctv.es/USERS/Softtech/motos

------------------------------

Date: Wed, 30 Sep 1998 00:33:27
From: Duncan Griffiths 
Subject: MC-Chassis Re: Head shake

The head shake I was talking about (TZ without damper) is almost to the
dangerous. At almost every corner exit it would at least wag the bars a
little bit.  It didn't get to a full-on tank-slapper as the damper still
had some oil left in it at the end of the sessions.  Under braking it felt
fine.  My thoughts were that it was only occuring when acceleration was
transferring weight to the back.  I'm sure that if I was silly enough to
run without a damper, it would have been much worse.

This was nothing compared to when I had to ride my crashed F-3 bike
(championship on the line you know!)  The wheels didn't even line up and it
would do tank slappers at several points on the track.  As the blood was
up, I considered this only an inconvenience at the time.

I've seen riders do a slow wobble all the way down the front straight, then
jump on the brakes for Turn 1 without any ill effects, but I could easily
see how it could get out of hand.  If you tensed up on the bars in the
middle of it, you could easily make the wobble/weave bad enough to toss you
off.  Now that would be embarassing: crashing half way down the main straight!

Duncan
===============

Is the head shake we are talking about something that is dangerous or just 
disconcerting? I once raced a Triumph that was bored out to 800cc in a stock 
frame and it would shake very hard coming out of corners at full throttle.
It was 
bad enough to scare riders following me, but it never felt dangerous.  It had 
wide flat track bars and was rather fun to ride. It probably would have been 
frightening with clipons. Any other bike I rode only seemed to shake a little 
when the front got light exiting a corner. I had heard of riders being
thrown off 
from speed wobbles but never saw it happen. A few races ago a rider I know 
said he got into a wobble that caused him to crash. I asked him about it
and he 
said it happened when he dumped the  clutch coming out of a corner. I don't 
know what else he could have expected. Maybe wide bars are the thing to try 
when dampers don't work.

Frank Camillieri

------------------------------

Date: Wed, 30 Sep 1998 08:44:21 +0100
From: Julian Bond 
Subject: Re: MC-Chassis Re: Steering dampers

In article <001101bdec41$16c858e0$938719d4@main>, Tony Foale
 writes
>For example, with today's very wide tyres there is plenty of opportunity for
>bumps and stones to contact the tyre considerably off centre, this obviously
>will produce a torque about the steering axis.

I've just been re-reading Performance Bikes analysis of the Suzuki TL
and this (along with this thread) has prompted a train of thought about
rear wheel and tyre size. PB ended up fitting a 5.5" rear wheel with a
170 or 180 tyre instead of Suzuki's 6" and 190-200 tyre. The end result
was better stability and more responsive handling.

Another example here are the general reports that the Ducati 748 handles
better than the 916 when the only real difference in chassis is a 5.5"
instead of a 6" rear wheel.

My own experience is that a 170 on a 900ss felt much better than a 180.

It makes me think that for a bike with less than say 120hp, the benefits
of a narrower rear wheel outway the corner exit gains of a bit more
grip. It seems that rear tyre size has become one of those stats that
the M/C manufacturers are trying to tell us "more is better" when the
truth may be the opposite.

With the current state of tyre technology, is there really any reason to
go bigger than 3.5" and 5.5" on any road based bike? Comments?

- -- 
Julian Bond                       )+(  mailto:julian_bond@voidstar.com
CN250/Helix/FF info & mailing list     http://www.shockwav.demon.co.uk
>8600 Bike Suppliers, Contacts & Addresses      http://www.bikeweb.com
                        > Makes 6-8 Sandwiches <

------------------------------

Date: Wed, 30 Sep 1998 07:05:50
From: batwings@i-plus.net
Subject: Re: MC-Chassis-Dgst SA Bushes

At 07:33 AM 9/30/98 +0800, you wrote:
>Just to add to the SA bush discussion.  When I was an apprentice Toolmaker
>I was riding a Z1000J (Kwaka).  One of the sales lines was that it had
>"Needle Roller Swing Arm Bearings" I always thought needle roller bearings
>were for things that rotated continuously. 

That's the crux of the problem: the little rollers get all the load and
fatigu on about 10% of their circumference. That means they break down
there first. Once they start to go off-round even by a hair, the process
proceeds with skidding as well as simply being loaded hard.

>To cure the Z1000 I made up Hardened and ground steel bushes and sleeves
>(just to be one better than bronze bushes)

Hate to disagree, but if the surfaces are equally hard and esp in steels
you do get seizing by virtue of self-welding. There is however still a
better substance than bronze and it *is* steel, but leaded steel, not
hardened steel. Leaded steels are free-machining, rather soft for steels,
abd extremely good bearing surfaces on hard or chromed steel inners.

>OK when you have a Toolroom at
>your disposal, that combined with a little SA stiffening and SH bracing
>made it ride pretty good.

You got it. Keep up the good work.

best regards,

Hoyt

------------------------------

Date: Wed, 30 Sep 1998 07:27:34
From: batwings@i-plus.net
Subject: Re: MC-Chassis Re: Head shake

At 10:20 PM 9/29/98 -0400, you wrote:
>said it happened when he dumped the  clutch coming out of a corner. I don't 
>know what else he could have expected. Maybe wide bars are the thing to try 
>when dampers don't work.

Can make it worse by coupling in more of your body weight, or at least
coupling it in on a longer moment arm, which lowers the resonant frequency
of the front end; it will then be excited at lower speeds. Since these
things are often faster and much stronger than humans anyway, the long bars
just get you shook around a lot more when it happens. Enjoy.

Have been amazing the dirt riders for years by using bars of 27-28"; not
only does this steer faster (muscles can get stronger but are limited by a
fixed contraction rate), but it also makes tree-dodging easier. For RR only
the former matters of course, unless you have unusual riding habits. 

Best wishes,

Hoyt

------------------------------

Date: Wed, 30 Sep 1998 07:35:06
From: batwings@i-plus.net
Subject: Re: MC-Chassis Introduction

At 08:02 PM 9/29/98 -0700, you wrote:

>Moss said that driven properly the Corvair wasn't either dangerous or
>"unconventional".  The problem was that "driven properly" meant that the
>driver knew how and didn't try braking in the middle of the curve, 'cause
>like the Porsche and VW, the car had trail-throttle over steer and would
>swap ends if the driver lifted in the turns.

Suitable for pros only? 

>In the ensuing suit, her lawyers alleged that
>the car was inherently unstable, Porsche responded that it was designed
>that way, for drivers who had a clue...  

That strikes me as unusually candid but a perfectly useless defense.

Best wishes,

Hoyt

------------------------------

End of MC-Chassis-Dgst V1 #778
******************************



MC-Chassis-Dgst     Wednesday, September 30 1998     Volume 01 : Number 779



 1. batwings@i-plus.net                  Subj: Re: MC-Chassis metal casting question
 2. Allen G  Subj: MC-Chassis re: RZ500 measurements
 3. "Calvin Grandy"    Subj: Re: MC-Chassis Re: Steering dampers
 4. bc180@freenet.carleton.ca (Peter Alan Engelbert) Subj: Re: MC-Chassis Re: Head shake
 5. "Peter Snell"        Subj: MC-Chassis Re: Single-sided swingarm revisited.
 6. Alan Lapp  Subj: Re: MC-Chassis Re: Head shake
 7. Bill Heckel            Subj: Re: MC-Chassis Steering Dampers
 8. Alan Lapp  Subj: Re: MC-Chassis Re: Head shake
 9. Lauren        Subj: Re: MC-Chassis Re: Head shake
10. "Frank Camillieri"  Subj: MC-Chassis Chassis adjustments

----------------------------------------------------------------------

Date: Wed, 30 Sep 1998 07:50:15
From: batwings@i-plus.net
Subject: Re: MC-Chassis metal casting question

At 08:02 PM 9/29/98 -0700, you wrote:
>Can anyone recommend a web site with good general reference
>information on Casting (especially sand casting aluminum alloy)
>and Pattern-Making?

rec.crafts.metalworking people field a lot of these questions and/or can
point you to other resources.

Best wishes,

Hoyt

------------------------------

Date: Wed, 30 Sep 1998 09:26:16 -0400
From: Allen G 
Subject: MC-Chassis re: RZ500 measurements

Hi Ray,

The measurements I need are of the stock RZ500 wheel-center, and
sprocket-center, relative to the stock RZ swingarm.  The idea is if I
know where these parts are located relative to the stock swingarm (the
part I still have), I'll be able to put the GSXR wheel/swingarm/... in
stock 'alignment' with the front wheel.

Allen G
Atlanta GA

------------------------------

Date: Wed, 30 Sep 1998 09:37:14 -0400
From: "Calvin Grandy" 
Subject: Re: MC-Chassis Re: Steering dampers

This is a multi-part message in MIME format.

- ------=_NextPart_000_01BDEC55.E81E0A20
Content-Type: text/plain; charset=ISO-8859-1
Content-Transfer-Encoding: 8bit

On this subject of out side forces acting off the steering axis.
 Let me describe an event that indicates an appropriate application for a
progressive (fixed orifice) damper at the steering head.  I am sure we all
have similar tales to tell.

The Scene: Spirited road riding in western Mass. returning from the
"Italian Meet" in Sturbridge. Road speed about 65 mph.

The event:  There was a bit of rough pavement.  The bars on my Morini (no
damper )
were violently jerked left then right. first by the off center hit of the
road hazard,( a dip or pot hole) then by the over correction swing due to
geometry and the tire.  Then all was straight again.

Result:  A fish hook tire mark in the road from the over swing, and two
sprained thumbs. A strong odor of perspiration, and a wonder of how one
could point two directions at once with neither direction the one being
traveled.
A hydraulic damper would have reduced the violence of this event
significantly.
The original equipment damper was a compressed rubber on shafting sort of
thing, offering decreasing damping with increasing speed, long since
removed.
I have a hydraulic damper almost finished, and a rotary unit is on the
drawing board for the coming off season.

Regards

Calvin Grandy




------------------------------

Date: Wed, 30 Sep 1998 10:14:30 -0400 (EDT)
From: bc180@freenet.carleton.ca (Peter Alan Engelbert)
Subject: Re: MC-Chassis Re: Head shake

>Have been amazing the dirt riders for years by using bars of 27-28"; not
>only does this steer faster (muscles can get stronger but are limited by a
>fixed contraction rate), but it also makes tree-dodging easier. For RR only
>the former matters of course, unless you have unusual riding habits. 
>
>Best wishes,
>
>Hoyt
>


Run off the track at Shubenacadie and tree-dodging is a skill you're going
to need. 

- --
Peter Engelbert: bc180@Freenet.Carleton.CA  or engelbp@mczcr.gov.on.ca
Vintage Road Racing: it's never too late to have a happy childhood. 

------------------------------

Date: Wed, 30 Sep 1998 11:40:34 -0400
From: "Peter Snell" 
Subject: MC-Chassis Re: Single-sided swingarm revisited.

> ------------------------------
> 
> Date: Tue, 29 Sep 1998 11:24:55 -0400
> From: "Gary Beale" 
> Subject: Re: MC-Chassis Single sided swingarm revisited
> 
> Hi Peter.
> 
> Somebody's point was that, with the appropriate length chain, large
> adjustments should never be necessary.  If you had a spare chain that was a
> couple links shorter, would you have been able to adjust the proper slack
> without undue ride height changes?
>
	 This is true to a point, but given the fact that the range of
adjustment isn't any larger than a conventional setup, it's a problem no
matter how you look at it. It's particularly bad when near the limits of
adjustment, as small changes in chain tension make large changes in ride
height. Remember too, that changing chain length is a discrete change.
In reality 3 chain lengths are about all that would be useful, and there
are always going to be awkward combinations. The other interesting
limitation was that you couldn't fit a rear sprocket larger than 40T, as
it would contact the swingarm.
   
> (Leaving aside the issue of breaking, installing, and carrying spare chains
> of different lengths!)

	Of course it's convenient to leave aside these issues for the sake of
argument, but not so convenient when you're at the track, your next
practice session is in 20 min, and you want to make a jetting AND
gearing change.;-)

> 
> Gary Beale
> gbeale@atlanta.dg.com

- -- 
__
Pete Snell

------------------------------

Date: Wed, 30 Sep 1998 11:54:51 +0100
From: Alan Lapp 
Subject: Re: MC-Chassis Re: Head shake

>I've seen riders do a slow wobble all the way down the front straight, then
>jump on the brakes for Turn 1 without any ill effects, but I could easily
>see how it could get out of hand.  If you tensed up on the bars in the
>middle of it, you could easily make the wobble/weave bad enough to toss you
>off.  Now that would be embarassing: crashing half way down the main straight!

I have a friend who bought a clapped out Honda F2 for his first racebike,
and promptly crashed it repeatedly.  He was complaining of a weave on the
straights, and asked me to look at his bike.  He was confused - he said he
didn't understand why racers said they relaxed on the straights.

The list of problems was long, but the main problems were: a slightly bent
front wheel (about 1/16" out axially), completely knackered steering head
bngs, a cracked lower triple clamp (yes, as in broken - one of the tubes
was receiving no support from the lower clamp), the forks were twisted in
the clamps, and crunchy wheel bngs.

For around $200 in new bngs and a used triple clamp, we returned the bike
to a stable ride for which Honda's are know.. without replacing the front
rim.

Al
level_5_ltd@earthlink.net

------------------------------

Date: Wed, 30 Sep 1998 12:27:07 -0400
From: Bill Heckel 
Subject: Re: MC-Chassis Steering Dampers

Griffiths, Duncan wrote:
> 
> The TZ figures are 22.5 degrees rake, 81.5mm (3.21") trail, and 53"
> wheelbase.  It's a bit steeper than that with the rear ride height
> adjusted up a bit.  The rake shouldn't affect stability.  Almost every
> race bike I've seen has a steering damper, so I'm sure it's just the fact
> that we're pushing the limits of all the components as Hoyt discussed (in
> a somewhat abstract manner).


I think that rules requiring dampers have a lot to do with people using them on race bikes also, if you don't have one, you don't race...

Bill

P.S.  How do you EX 500 types mount a damper so that it doesn't restrict steering travel.  ( street EX with full fairing )

------------------------------

Date: Wed, 30 Sep 1998 12:03:01 +0100
From: Alan Lapp 
Subject: Re: MC-Chassis Re: Head shake

>At 10:20 PM 9/29/98 -0400, you wrote:
>>said it happened when he dumped the  clutch coming out of a corner. I don't
>>know what else he could have expected. Maybe wide bars are the thing to try
>>when dampers don't work.
>
>Can make it worse by coupling in more of your body weight, or at least
>coupling it in on a longer moment arm, which lowers the resonant frequency
>of the front end; it will then be excited at lower speeds. Since these
>things are often faster and much stronger than humans anyway, the long bars
>just get you shook around a lot more when it happens. Enjoy.
>
>Have been amazing the dirt riders for years by using bars of 27-28"; not
>only does this steer faster (muscles can get stronger but are limited by a
>fixed contraction rate), but it also makes tree-dodging easier. For RR only
>the former matters of course, unless you have unusual riding habits.

This discussion brings to mind an absolutely amazing thing I saw at Summit
Point last year.  The bike was the Dutchman Racing YammaMonster (highly
modified FZR1000, and ooh, don't get me started on the radiator - it's a
work of art!), and I believe the rider was Fritz Kling, but I could be
wrong.

In any case, the rider ran wide in T10, which is a fast (80mph+) RH turn
with a rumble strip on the outside of the turn.  The bike was on the rumble
strip, and behaving very badly, and looked like a tank slapper was iminent.
The rider dipped the clutch, opened the throttle and wheelied out of the
corner, immediately stopping the instability.  It was thrilling to see!

Al
level_5_ltd@earthlink.net

------------------------------

Date: Wed, 30 Sep 1998 09:59:58 -0700
From: Lauren 
Subject: Re: MC-Chassis Re: Head shake

At 04:03 AM 9/30/98 , Alan Lapp wrote:
>
>In any case, the rider ran wide in T10, which is a fast (80mph+) RH turn
>with a rumble strip on the outside of the turn.  The bike was on the rumble
>strip, and behaving very badly, and looked like a tank slapper was iminent.
>The rider dipped the clutch, opened the throttle and wheelied out of the
>corner, immediately stopping the instability.  It was thrilling to see!
>

I guess that is one way to bring the steering under control - eliminate the
steering ;-)

Unfortunately my somewhat sedate BMW can't pull wheelies at anywhere near
80 MPH, so I will have to find another solution ;-)

FWIW,
LCB

'91 BMW R100GS - Geist der Freiheit
'94 Suzuki DR350ES

------------------------------

Date: Wed, 30 Sep 1998 12:48:34 -0400
From: "Frank Camillieri" 
Subject: MC-Chassis Chassis adjustments

I am finding it hard to believe an 8mm change in wheelbase or ride height could 
be felt by anyone short of a Doohan caliber rider. (and maybe not even him) I 
returned to racing this year on a Triumph I built for a friend 30 years ago and I 
didn't change the old Girling dampers for the first few races. When I got around 
to replacing them I found that one was bent and had a heavy single rate spring 
and the other had a lighter dual rate. I didn't feel much difference with the new 
dampers. I did fall off twice with the old dampers, but it was a wet track both 
times and I can't blame the dampers for that.

Frank Camillieri
Chester, NH

------------------------------

End of MC-Chassis-Dgst V1 #779
******************************



MC-Chassis-Dgst       Thursday, October 1 1998       Volume 01 : Number 780



 1. Ed Scharnhorst   Subj: MC-Chassis re: RZ500 measurements
 2. "Peter Snell"        Subj: Re: MC-Chassis-Chassis adjustments
 3. yhakim@m5.sprynet.com                Subj: MC-Chassis Aluminum twin spar/welding
 4. "Ray or Emily Brooks"  Subj: Re: MC-Chassis metal casting question
 5. "Ray or Emily Brooks"  Subj: Re: MC-Chassis re: RZ500 measurements
 6. Br69br69br@aol.com                   Subj: Re: MC-Chassis metal casting question
 7. "Michael Moore"   Subj: Re: MC-Chassis Aluminum twin spar/welding
 8. "Michael Moore"   Subj: MC-Chassis Another list?????
 9. batwings@i-plus.net                  Subj: Re: MC-Chassis metal casting question
10. Bob & Jean    Subj: Re: MC-Chassis rake,trail and wheelbase stuff

----------------------------------------------------------------------

Date: Wed, 30 Sep 1998 13:47:50 -0400
From: Ed Scharnhorst 
Subject: MC-Chassis re: RZ500 measurements

Hi Allen,
I recall seeing a RZ500 specific mailing list out there somewhere. You might try them. And I know I've been to a web page about the 500's. If
that doesn't work, the 500 I've seen had stock wheels that look suspiciously like FZ-750's (including the internally vented sandwich front
rotors). Not that Yamaha has ever raided parts bins to produce a bike! ;->
Ed Scharnhorst

ps. Oooh,oooh! Found it!  http://www.motorcycle.com/rz_club/
Good luck!

> From: Allen G 
> Subject: MC-Chassis re: RZ500 measurements
>
> Hi Ray,
>
> The measurements I need are of the stock RZ500 wheel-center, and
> sprocket-center, relative to the stock RZ swingarm.  The idea is if I
> know where these parts are located relative to the stock swingarm (the
> part I still have), I'll be able to put the GSXR wheel/swingarm/... in
> stock 'alignment' with the front wheel.
>
> Allen G
> Atlanta GA
>

------------------------------

Date: Wed, 30 Sep 1998 17:11:35 -0400
From: "Peter Snell" 
Subject: Re: MC-Chassis-Chassis adjustments

> 
> Date: Wed, 30 Sep 1998 12:48:34 -0400
> From: "Frank Camillieri" 
> Subject: MC-Chassis Chassis adjustments
> 
> I am finding it hard to believe an 8mm change in wheelbase or ride height could
> be felt by anyone short of a Doohan caliber rider. (and maybe not even him) I
> returned to racing this year on a Triumph I built for a friend 30 years ago and I
> didn't change the old Girling dampers for the first few races. When I got around
> to replacing them I found that one was bent and had a heavy single rate spring
> and the other had a lighter dual rate. I didn't feel much difference with the new
> dampers. I did fall off twice with the old dampers, but it was a wet track both
> times and I can't blame the dampers for that.
> 
> Frank Camillieri
> Chester, NH
> 
	Of course anyone is free to believe what they want, and most people
make decisions based on their own experiences. Some riders can get on
anything and ride it fast. Other riders know what is keeping them from
comfortably riding faster, and how they can correct, or at least lessen
the problem. 250 GP bikes are extremely tweaky beasts. They have rigid
frames, swingarms and forks. The suspension is top quality. They use
slick tires with very high grip. Good riders know how to set them up to
suit their style and the track surface. The rider I work with is a
National caliber rider with a LOT of experience. He knows what effect
chassis adjustments have and can make critical decisions about what is
slowing him down. When setting the bike up, the stopwatch makes the
decisions. If the change didn't yeild a faster lap time, or at least
more consistently fast lap times, then we look elsewhere. If we go
backwards, it's back to the old settings. Remember, we're talking about
shaving off times of less than a second generally.

	Your average club rider on an EX500 probably wouldn't notice the
difference, it's just to flexy, has lots of trail, and he's probably
ridden at 3 tracks in his entire career. Not helping matters is the fact
that he probably can't string 5 laps together that were within 1/2
second of each other to save his life. 10mm of ride height probably
won't help him or likely hurt him either. But if he doesn't ever play
around a bit, he'll never know if his setup could be better or not. 
- -- 
__
Pete Snell

------------------------------

Date: Wed, 30 Sep 1998 16:42:19 -0700
From: yhakim@m5.sprynet.com
Subject: MC-Chassis Aluminum twin spar/welding

Is the main advantage of an aluminum twin spar chassis mass production 
cost? Also is there any benefit to using extruded Al vs sheet Al welded 
in to a box section? Can you bronze weld Al?
______________________________________________________
Yousuf
	
______________________________________________________  

------------------------------

Date: Wed, 30 Sep 1998 19:55:45 -0400
From: "Ray or Emily Brooks" 
Subject: Re: MC-Chassis metal casting question

Eastwood has a book about sand casting. It is a very involved process. I
have a scrap metal yard across the street from my shop. They melt aluminium
engines and other alloy bits that have steel cast into them. The "pure"
ingots bring alot more money than the "Steelie" bits. I have thought of
making a sand mold to create a radial head for my Hodie trials bike. Billet
would be much easier.

Ray

- ----------
> From: David Weinshenker 
> To: mc-chassis-design@list.sirius.com
> Subject: MC-Chassis metal casting question
> Date: Tuesday, September 29, 1998 11:02 PM
> 
> Can anyone recommend a web site with good general reference
> information on Casting (especially sand casting aluminum alloy)
> and Pattern-Making?
> 
> -dave w

------------------------------

Date: Wed, 30 Sep 1998 20:00:38 -0400
From: "Ray or Emily Brooks" 
Subject: Re: MC-Chassis re: RZ500 measurements

Jason at Yamaha of Doraville has a RZ500. Give him a call.

Ray

- ----------
> From: Allen G 
> To: mc-chassis-design@list.sirius.com
> Subject: MC-Chassis re: RZ500 measurements
> Date: Wednesday, September 30, 1998 9:26 AM
> 
> Hi Ray,
> 
> The measurements I need are of the stock RZ500 wheel-center, and
> sprocket-center, relative to the stock RZ swingarm.  The idea is if I
> know where these parts are located relative to the stock swingarm (the
> part I still have), I'll be able to put the GSXR wheel/swingarm/... in
> stock 'alignment' with the front wheel.
> 
> Allen G
> Atlanta GA

------------------------------

Date: Wed, 30 Sep 1998 20:05:43 EDT
From: Br69br69br@aol.com
Subject: Re: MC-Chassis metal casting question

Before doing either I would seriously look into the heat dissapation
properties of each. When you melt down most alloys you greatly change thier
properties.

------------------------------

Date: Wed, 30 Sep 1998 17:06:57 -0800
From: "Michael Moore" 
Subject: Re: MC-Chassis Aluminum twin spar/welding

> Is the main advantage of an aluminum twin spar chassis mass production 
> cost? Also is there any benefit to using extruded Al vs sheet Al welded 
> in to a box section? Can you bronze weld Al?

Hello Yousuf,

Sheet fabrication gives you more freedom in putting the material 
where you want it, rather than having a constant cross-section 
throughout the spar.

Bronze welding is for steel.  You can get some aluminum brazing rods 
but you'd probably be best off welding the aluminum instead.

Cheers,
Michael


------------------------------

Date: Wed, 30 Sep 1998 19:38:01 -0800
From: "Michael Moore" 
Subject: MC-Chassis Another list?????

Is there anyone interested in a Benelli/MotoBi list?

I've got about 14 people on my very informal distribution list 
devoted to the Benelli/MotoBi horizontal singles, but I've had 
inquiries from people with Seis, Quattros, and Tornados, as well as
the vertical cylinder singles (and even a 65cc Dynamo minibike).

I didn't think there was much chance of the Suzuki GS-twin and 
Laverda lists getting beyond 15 or 20 listees, yet they are both up to
about 85 people each.  

If I can get about 25 people interested in a Benelli/MotoBi list I'll
see about starting one up at the beginning of November when I get back
from my trip to Spain.

Please drop me a line off list if you would be interested.

Cheers,
Michael

------------------------------

Date: Thu, 01 Oct 1998 07:11:17
From: batwings@i-plus.net
Subject: Re: MC-Chassis metal casting question

At 08:05 PM 9/30/98 EDT, you wrote:
>Before doing either I would seriously look into the heat dissapation
>properties of each. When you melt down most alloys you greatly change thier
>properties.

If that's true, the properties will be regained when cast. Very few items
in the MC and auto world are fully machined from billet, therefore they
have already been cast. In fact, however, melting and casting them changes
little. The heat conductivity would be the one property probably changing
the least.

Best wishes,

Hoyt

------------------------------

Date: Thu, 01 Oct 1998 11:30:19 -0700
From: Bob & Jean 
Subject: Re: MC-Chassis rake,trail and wheelbase stuff

Michael Moore wrote:
 
> Also, I'd think that the forks might have more leverage on the
> steering head the steeper the rake as the braking force would be fed
> in at something more closely approaching a right angle letting the
> force mainly twist the steering head instead of trying to push it
> backwards as well.
> 
> Cheers,
> Michael
>
Hmmmmm,Is this true? In my personal limited RAM I'm thinking that if the
vertical height is the same in both cases, ie, center of wheel to
reaction center between 2 steering head bearings, then the horizonal
vector will be the same. Cheers Bob

------------------------------

End of MC-Chassis-Dgst V1 #780
******************************



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