Re: Brembos, big reds, etc.

[John Karasaki <johkar@teleport.com>]

Paul,

No flames from me, really.  Just a rebuttal.

If you read my post to the q-list after the Porsche track event, you will
see that I do NOT totally disagree with you.

If I were going to track the V8, a '91 200tq or S4/S6 I would use the new
Carrera calipers and either the S6+ or if money was no object, 993TT rotors
or a racing rotor equivalent.  I re-iterate from my past post: IMHO, you
need at LEAST a rotor that will just fit under a 17" wheel to track a 4000
lb. car.  I'll also add that we are all FOOLS for wanting to track
3700-4000 lb. cars in the first place, but that is another subject entirely.

The rotor is the most important part of the system.  Is the A8 rotor a
compromise?  You bet.  What else, however, is available over the counter,
in the right bolt pattern, cheap, and will fit (just) under a 16" wheel?

I've said it before, and I'll say it again.  If money were no object, I
would NOT use the Big Red calipers.  They are OLD technology.  They are big
and heavy relative to any of the mono-block high tech calipers Porsche has
to offer.  The big reds have to be big to not twist under braking.  Compare
a big red caliper to a Boxster caliper.  One is very crude.  Hint: it's not
the newer one. 

The pads on the big reds are a little bigger yes, and the big red calipers
themselves are huge compared to the monoblocks.  This bigger size and mass
is not an advantage (talking about caliper, not pads here -- of course the
bigger pads are better).  This is so they can get adequate distance between
the bolts that hold the 2 caliper halves together (to prevent the twisting
that I mentioned above).  Don't get me wrong, the Big Red* (and big black
and big yellow if you can get it) calipers were a great caliper based on
'80s technology.  You won't see many new Carrera owners back dating their
brakes, however.

I like most, was all fired up to get some big reds for our car.  The local
Porsche speed shop guys talked me out of it.  They and their competitors
aren't designing any new brake kits around the big reds.  Everything is
Boxster and new Carrera calipers, baby.

I agree with you that just because it can be done, that doesn't mean it
should.  However, just because it is red and huge doesn't mean it is the
"Best" either.  The boxster calipers are puny because they can be.  They
are still much more rigid than the big reds.

I don't follow at all your comment that "the heat sinking capabilities of
the housing are small."  There is a fundamental disconnect in your thinking
here.  You don't want the calipers to hold or take on ANY heat if you can
help it.  That is why the good brake pads have a ceramic barrier between
the friction material and backing plates -- to prevent heat from getting to
the caliper pistons.  You don't want a massive caliper.  That mass is
thermal mass, a thermal storage device if you will that will contribute to
boiling your brake fluid.  Might want to think about that one again.

I also don't agree with your reasoning about A4 and A8 owners' warped rotor
complaints proving that the A8 rotors are poor.  I have talked to a few
Factory Audi mechanics about it (one who helped design another brake kit
for the S-cars) and there is more to it than the rotor.  The key there is
that Audi uses a single piston floating caliper with the A8 and A4 rotors.
This single piston only applies pressure to the center of the brake pad.
Under normal use, the pads, due to the floating caliper engagement, are
allowed to "squirm."  This is maybe what causes the warping.  Coasting to a
stop (as most drivers do) in normal driving only makes matters worse.  We
in the USA got screwed with crappy OEM calipers again.  I believe the rest
of the world got 4 piston calipers (Anyone care to verify this?  Ned?)

The kit Greg and I have on our cars (which probably will never be sold to
anyone else) work EXCELLENT on the street where 99% of our driving takes
place.  The advantage besides being far less than half the cost of the
Mov'it kit is that pedal feel is improved, not reduced (you lose a bit of
brake pedal travel with ALL the big red kits; that is, the first ~1" of
travel gives you nothing then whoa! you have brakes).  There was ZERO
reprogramming time for my wife with our kit.  She just started the car and
drove down the road with a grin on her face.  If you weren't into Audis or
never had driven one, you could drive our V8 after driving your BMW without
compromising your stopping experience.

Having said all this, the reality is, Paul, that the typical Audi driver
will never spring for a Mov'it kit.  Heck, most wouldn't spring for our kit
if it were ever available.  Even more are running around with crappy Metal
Master or K-mart brake pads.  Most would drop $1000+ on a car stereo or
cool wheels before spending a nickel on brakes.  So I guess all this is
academic.

That said, for the COST, there is NO other street brake upgrade out there
for the S4/S6 and V8/20vtq with G60s cars that can come close to the
performance of the Boxster/A8 setup.  It is an excellent VALUE.  AND I say
this with the intention of NEVER selling a single brake kit.  There just
isn't any profit in the A8/Boxster kit.  There sure is liability, though.

DISCLAIMER: DO NOT TRY ANY OF THIS AT HOME.

John Karasaki
'82 urq w/ G60's
'86 4kq w/ G60's
'87 coupe w/ no front clip
'87 5ktqw w/ G60's
'90 V8 with great street brakes and enough cash left over to take a cruise...

*There are alot of Porsche calipers that are big and red.  If you have a
kit that uses a big and red Porsche caliper under a 16" wheel, you don't
have the "Big Red" calipers the Porsche guys talk about.  You have the
similar caliper that came on the 944 turbo 'S' and 928 S4 cars.  It uses
the exact same brake pads as the Big Reds, but were designed to fit under
16" wheels by Porsche.  If you don't believe me, ask your brake kit
supplier.  If you don't trust their marketing hype, call Todd Candy and
chat with him for awhile.  He'll set you straight.  You could also ask
Scott Justinson why a 17" wheel is REQUIRED with his kit as well.  Both
good folk that have given more than their fair share of time to this list.

At 12:39 PM 5/12/99 -0700, Paul E. Rivera wrote:
>Personal opinions on brakes. No flames please.
>
>I have done a little research on the latest moves  by members to put 4
>pot boxster
>brakes on a 3500+ lb car (200's, 5Ktq,s, etc.) Even a A4 Quattro is no
>lightweight.
>This caliper is about the size of the rear brakes on a 993.
>Kind of pint size.  Not only is the square inches of pad surface small,
>the heat sinking capabilities of the housing are small, and the clamping
>force of the caliper itself is small. This Caliper would be suitable for
>a small FWD coupe like the GT, or maybe at worst case a Ur-Q. I realize
>they are cheap, but if you are trying to get a reliable increase in
>stopping power, especially if you are using them on the track, you are
>going to wind up at the end of a amateur brake engineer failure test.
>
>
>A8 Rotors, S6 Rotors are decent stock rotors, but they are not even in
>the same league
>as the Porsche Rotors used in the 993  front and 993TT front.
>
>A4 and A8 owners have experienced severe rotor warp with only a day on
>the track.
>
>Big reds. Seems to be two different Big Reds. 993, (351-421-00) and
>993TT (351-425-10) There is a 24% difference in pad size, let alone
>differences in piston and housing size. It all counts.  Compare these
>calipers to the Boxsters, it is a world of difference.
>
>Just because you can make'em fit, does not mean they are right.
>
>Paul Rivera
>91 200 TQA (Big reds in boxes waiting for wheels)
>94 S4 with Big Reds
>
>