[Biturbos4] Shuddering brakes (StopTech) EZ fix - long

[Grant]

A very light sanding might help, but 99.9% of shops will "turn" the 
rotor, meaning
they will put it on a lathe and machine it flat.  This thins the rotor, 
making it even
more prone to warping and is not recommended, either by Audi or anyone 
I know.
New rotors, over the internet, from, say, GPR are about $75/ea.

So I'd live with it as I do, or maybe check the pads as Single Malt 
suggested,
or, if you want perfection, replace the rotors.  I would not turn them.

Grant
On May 29, 2005, at 11:18 PM, Rohan Singh wrote:

> I really enjoy hearing about these problems which we
> all seem to ultimately experience at some point! I
> have been experiencing exactly the same problem (with
> OEM brakes though - Lucas). Took the car to the dealer
> and he wanted to change replace the discs (around $450
> Cdn) since there was apparently some pad deposit. I
> asked if could sand the discs down - he said Audi
> policy prevented him from doing this but in a lower
> tone said I could go somewhere else and have this
> done! Stupid right?! Of course, I declined the
> replacement and over the next few days did some
> emergency braking at high speeds which has resulted in
> significant improvement but not completely eliminated
> the problem. This only happens when I brake hard at
> say 120 - 140 km per hour. I get a shuddering at the
> steering wheel mainly. Do you recommend trying to
> sand/machine the disks down? Thanks.
>
>
> --- Grant <gfl1 at optonline.net> wrote:
>
>> Thanks for the note.
>>
>> Earlier, someone wrote that even with OEM S4 brakes,
>> what is often assumed to be warped rotors is often
>> excess material on
>> the pads
>> (or maybe uneven wear).  That writer recommended
>> "panic" stops to clean
>> them
>> and maybe re-bed them.  With little to lose, I tried
>> this, and it did
>> help.
>>
>> It didn't totally cure the ill, but made it
>> noticeably better.
>>
>> So these types of reports, with real experience
>> rather than just
>> 14th-hand opinion, are
>> very welcome and valuable in my book. Thanks for
>> taking the time to
>> share.
>>
>> Grant
>> On May 29, 2005, at 1:56 PM, Single Malt wrote:
>>
>>> I thought I'd share a recent repair I performed on
>> my
>>> car.  For many of you this will be unworthy of the
>>> time it takes to read, but perhaps some will find
>> this
>>> interesting.
>>>
>>> After a recent track event, my brakes developed a
>>> shudder that was not too severe, but needed
>> attention.
>>>  A fellow Audi club member was kind enough to
>> offer
>>> some guidance on a resolution path that would be
>> quite
>>> simple ... Being a little wary of DIY'ing things
>> as
>>> important as brakes, I bribed him with dinner and
>> he
>>> came over to help out.
>>>
>>> Among the possibilities of what was causing the
>>> shudder ranging from pad deposits on the rotors to
>>> warped rotors (which is apparently fairly rare)
>> was
>>> his suspicion that the pads were damaged or uneven
>>> from a poor bedding in process early in the pads
>> life.
>>>  Armed with new pads (in the event that the
>> existing
>>> pads were indeed shot), we dug in.  Our objective
>> was
>>> to inspect the brake pads and, if needed, sand
>> them
>>> flat again.  A test drive would determine if the
>>> shudder's cause was something else.  The rotors
>> would
>>> be visually checked at the same time.
>>>
>>> Please forgive my ignorance of the correct
>> semantics
>>> as I describe the process.
>>>
>>> Tools: jack, 17mm socket (for wheel removal),
>> torque
>>> wrench for 90ft/lb torque when replacing wheel,
>> 6mm
>>> allen wrench, rubber mallet or hammer and wood
>> block,
>>> screwdriver, sandpaper.
>>>
>>> Working from one side at a time, we removed the
>> wheel
>>> and turned the steering to expose the caliper for
>> ease
>>> of access.  The StopTech caliper has an I-shaped
>>> retaining piece that is fairly easily removed by
>>> removing the two long allen-headed bolts from top
>> and
>>> bottom.  A little screwdriver prying and this
>> retainer
>>> pops out (along with a rounded rectangle that acts
>> to
>>> secure the pads in position).  Grasping the ears
>> of
>>> the pad with a channel lock pliers, I could wiggle
>> and
>>> pull until the pad was extracted through the
>> access
>>> point opened by removing the I-shaped retainer.
>> The
>>> pad looked OK, but did have evidence of slightly
>>> uneven wear.  Laying my 80-grit sandpaper on the
>>> garage floor, I lightly ran the pad over the paper
>>> several times.  The sanding action revealed the
>> truth
>>> of it's uneven surface.  The leading and trailing
>>> edges of the pads were feathered or rounded off.
>>> After sanding until the entire pad was evened out,
>> I
>>> replaced that pad and extracted the next.  Same
>> wear
>>> was evident so I repeated the process.  The pads
>> were
>>> in otherwise fine shape.  With the StopTech's, it
>> was
>>> necessary to be cautious that the rotor stayed in
>>> place as it would easily shift out of position
>> with
>>> the pads missing.  Because I was not replacing the
>>> pads, pushing the brake pistons back in was not
>>> needed, however the pads did need a little tapping
>> to
>>> get them back into place.  Replacing the I-shaped
>>> retainer required a little tapping with a hammer
>> and
>>> wooden block to get it seated enough to replace
>> the
>>> allen-headed bolts.
>>>
>>> The test drive proved our efforts were successful,
>> the
>>> grilled burgers were good and the beer was cold
>> ... a
>>> good night overall!
>>>
>>> Repair time ... maybe 45 minutes, but it was a
>>> learning session so next time I expect maybe 20
>> (and
>>> that includes jacking up the car and removing the
>>> wheels).  While certainly not a "mechanic" per se,
>>> I've done a number of maintenance and repair
>>> procedures (spark plugs, oil changes, filters) to
>> my
>>> car and have a background that includes some minor
>>> mechanical work ... IMO, this job was easy.  I
>> think
>>> replacing the cabin filter took more time!
>>>
>>> The last time I had this shudder (after a track
>> event
>>> then too), it was with stock brakes and the rotors
>>> (while not warped) were in need of replacement ...
>>> hence an opportunity for the StopTech's.  This
>>> procedure was significantly cheaper! :)
>>>
>>> Disclaimer:  This is not meant to be a How-To.  It
>> is
>>> a diary of what I did.  I am an untrained moron.
>> If
>>> you follow this procedure yourself, I cannot be
>> held
>>> responsible for any property damage or personal
>>> injury.
>>>
>>> --
>>> Single Malt
>>> '01.5 S4
>>> Garaged at 9200ft
>>> just outside Denver, CO
>>>
>>>
>>> 		
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>>
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