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

[Rohan Singh]

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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