RE: brake shimmy (bad!)

[Sachelle Babbar <sbabbar@iris.nyit.edu>]

if a tire is out of round, at different speeds, you may see the entire car
shift back and forth noticeably. Problem may alleviate at varying speeds.

My brake rotors are warped. Same damn problem. Shimmy and violent shakes
under light braking to moderate to heavy.

Solution was listed by a memeber years ago on how to straighten warped
UFO's. I tried this on my old turbo and recently on my current one.

Use good judgement and **extreme** caution.

Drive on deserted highway, 65 to 70 miles an hour. Drag brakes. Steering
will shimmy violently, but controllable. Drive until it begins to reduce
somewhat (may be like 5-10 minutes) you want the rotors hot. BTW: do a
couple of warup stops (not panic stops) to prevent further warping (if
any).

Next, **SLAM** on the brakes to induce lockup or abs actuation. Drive an
extended period on the highway only to adequately cool the brakes. Do not
go back any where where yo have to stop. Heat will transfer to the
calipers and you'll just have a heat soak nightmare. You'll probably smell
pads roasting. Whatever

About 20 minutes later, you'll have better rotors.

I, again, advise extreme caution and will say that after the panic stop,
your brake effectiveness will be compromised.

A full bleeding should be in order after, but not necessary, as I've
experienced.

I do this on the Northern parkway at night.

This worked for me and the rotors haven't warped since. 


****************************************************************************
*Steve                                             Sachelle Babbar
*'87  5000CS Turbo 5spd 1.3-2.0 bar             <SBABBAR@IRIS.NYIT.EDU>
*Cockpit adjustable wastegate, AudiSport badge
*
*Disclaimer:"Any information contained herein is based purely on my own
*personal experience and may not necessarily reflect yours. Use caution as
*your results may vary from mine."
********************************************************************************
                                                                               



On Thu, 18 Nov 1999, TM wrote:

> Sounds like it may be any one of these factors. Warped rotors,
> out-of-balance
> wheel, bad alignment, etc. Also, tires can be out-of-round. My friend had
> this problem in his car when he bought new tires.
> 
> Finally, something I can comment on with some knowledge, besides A8 intros
> and my own questions!
> 
> Regards,
> Taka Mizutani
> 
> -----Original Message-----
> From: owner-quattro@audifans.com [mailto:owner-quattro@audifans.com]On
> Behalf Of D.A.K.
> Sent: Thursday, November 18, 1999 6:26 PM
> To: quattro@audifans.com
> Subject: brake shimmy (bad!)
> 
> 
> 
> What do you make of this?
> 
> On my '87 5KTQ, I get a terrible shimmy when I brake at highway speeds
> (about
> 70mph). When I'm driving on surface streets (around town), it is smooth.
> The steering wheel shakes violently when this is happening.
> 
> Some may remember my recent front suspension overhaul. I did the control
> arms,
> tie rod ends, and upper strut bearings and bushings. I had the shimmy before
> all of that work. I thought it was bad ball joints and had confirmed play in
> one of them.
> I have the car sheduled for an alignment next tuesday and would like to
> figure
> this out by then. I'm using my old snow tires for now (so I don't trash my
> new tires). Could something like low tire pressure, slightly warped brakes
> or something else cause this? I replaced my front brake disks/pads 1.5 years
> ago.
> 
> My wheel bearings/axles are in good shape. The steering rack is Jorgen from
> 2.5
> years ago.
> 
> Thanks for any insights!
> 
> David Kavanagh
> 
> PS. Also, my drivers side door handle is almost non functional now, my key
> sometimes gets stuck in the ignition (can't turn totally off to extract it),
> and several other maladies... When it rains, it pours. I'm currently
> planning
> to have this car last another 5 years for me. Let's hope!!
> 
>