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

[Grant]

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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