[s-cars] Cold start issue, brake fade

Tue Oct 10 15:31:49 EDT 2006

IIRC, I read somewhere the main culprit was supposed to be the piston seal
design in the G60. Now, the Coupe Quattro also use the G60 with 11" rotors
and has a much better pedal feel so I really can't tell for sure.

Now, if you're in for a second flush, I would strongly suggest you replace
your pregnant wife with a pressure bleeder (for the fluid flush, I mean). It
makes the job easier and much faster, beside being a more reliable procedure
for air bubbles. Pressure bleeder are available at almost any car tools
suppliers, either online or local.

Vincent.

2006/10/10, Mark Rivera <mrivera at webcats.net>:
>
> Thanks for the tips.  Sounds like I should really find a belly pan now...
> I'm fairly certain the fluid is the major culprit.  I'll get it back up on
> jackstands and start over.  This time I'll use someone besides my pregnant
> wife as a pedal pumper.  :)
>
> So tell me, what is it about the stock calipers that makes the pedal feel
> so
> bad?  Sorry, I'm just trying to understand how they can be a factor.
>
> Mark
> -----Original Message-----
> From: Vincent Frégeac [mailto:s.sikss at gmail.com]
> Sent: Tuesday, October 10, 2006 2:21 PM
> To: Mark Rivera
> Cc: S-Car-List; Theodore Chen
> Subject: Re: [s-cars] Cold start issue, brake fade
>
>
> Mark,
>
> As you mentionned your pedal was close to the floor, I suspect the fluid
> you used was contaminated with water. I suggest you flush it again, using
> fresh Castrol GT LMA or ATE, both high boiling point and reasonnably
> priced,
> flushing the calipers and also the master cylinder, in fact in reverse
> order
> IIRC, MC first then calipers. I personnaly use the Castrol and never had a
> problem with it, even when I forgot to reinstall the belly pan after
> servicing the car (BTDT a few times).
>
> Beside, with the mushmallow pedal feel of the stock calipers, bad pad
> fading can also lead to a pedal going to the floor with almost no braking.
> In fact, the pedal would also go to the floor with good pads, it's just
> that
> your S4 will be up on its front wheels way before the pedal reach the
> floor.
> I personnaly use Pagid for pads, street savour (good initial grip, no fad,
> reasonnable dust), because my usual part suppliers always have them stock,
> but there's a lot of other good options.
>
> You can also install Paul's Frankenduct, which is simply a dryer duct vent
> installed in the wheel liners so the air coming from the intercooler and
> oil
> cooler flows directly on the brakes, I mean, when the belly pan is
> installed
> and some air is actually flowing through the intercooler and oil cooler.
> BTW, for the belly pan, you can contact Force 5 or Shokan. They should
> have
> a few used ones.
>
> Regarding the pedal feel, the braided lines are a pure waste of money with
> the stock calipers, IMO. These calipers create a pedal feel which is so
> bad
> you won't notice any difference changing the brake lines. The only
> advantage
> is they will make your wallet lighter, thus slightly increasing the power
> to
> weight ratio of your S4 with driver with wallet (BTDT, but with an S6).
>
> Now, servicing the rear calipers can make a difference. If the hand brake
> mechanism in the rear calipers is jammed or partly jammed, it can have an
> impact on the pedal feel. When the rear calipers will be nice and shinny,
> just get used to pull the handbrake once a day to keep the rear pads close
> to the rotors (BTDT on three Audis).
>
> My 0.02$
>
>
>
> Vincent.
>
>
> 2006/10/8, Theodore Chen <tedebearp at yahoo.com>:
>
>    --- Mark Rivera <mrivera at webcats.net> wrote:
>    >
>    > I flushed and bled the brakes last night, and while it firmed up the
> pedal a
>    > little, it's still softer than I'd like.  I'll probably invest in
> some
>    > braided lines soon.  I took the car for a spin after I was done, and
> tried
>    > some heavy braking from about 80-45mph.  After about 3-4 applications
> like
>    > that, the brakes were fading really bad.  My foot was almost to the
> floor, I
>    > was almost out of my seat standing on the pedal, and could not get
> the
> ABS
>    > to activate.  Matter of fact I've never had the ABS step in yet, and
> I
>    > haven't locked a wheel yet either.  I cruised for about 5 minutes to
> cool
>    > things down, tried again, and most of the braking had returned.  I
> know the
>    > brakes are sorta weak on these cars, but I didn't know it could be
> this bad.
>    > I don't wanna pony up for a caliper/rotor upgrade just yet, but would
> like
>    > some pad suggestions to replace what I think are stock pads with wear
>    > sensors.
>
>    mark, what kind of fade?  did the pedal soften and go lower?  or did
>    it stay firm, and just feel like higher effort?  the former suggests
>    brake fluid fade, the latter suggests pad fade.  you could also have
>    both.  did you use fresh brake fluid from a sealed container?
>
>    the stock brakes aren't very good, but braking 120-0 on a steep
> downhill
>    worked fine although the effort got noticeably higher (pad fade).
>
>    -teddy
>
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