[200q20v] Re: [s-cars] Big Reds (actually Blacks)

QSHIPQ at aol.com QSHIPQ at aol.com
Wed Nov 7 08:41:35 EST 2001

>My other .02 here is, no offense meant to Scott, but these rotors and
>calipers were designed to work as a system, with specific components
>matched to work with other specific components. Not using the pieces in
>the correct manner with the correct parts can lead to system failure. I
>recall going through this a year or so ago on this list to the point
>that I gave up and left the list completely. For instance, as I recall,
>and I may be slightly off on my recollection, but BIRA was doing a kit
>that used a Porsche caliper designed for a 32 mm thick rotor with an A8
>rotor that, as I recall started as a 30 mm thick rotor.

A8 is 30mm, S8 is 32mm.    I don't think you have your "facts" right, but I
don't take offense at anything you post Michael.  All kits that I've
installed, that have my name asscociated with them, are using a 993tt and a
330x32mm rotor, and are lighter than the factory G60's.  That said, Movit
will put 299-380 on the same caliper, I've serviced a few 993tt with the A8
rotor with no piston boot problems.  There are plenty of folks (like a lot)
on the S car list with this setup, that are scratching their heads at your
"claims" vs btdt.

>The significance
>of this is Porsche and Brembo clearly state the wear limit on the rotor
>is 2 mm. Meaning when the rotor is down to 30 mm thick it is done...
>Throw it out and get a new one! Why? Because that is the design limit of
>the caliper.

NO.  That is the design limit of the ROTOR.

>If you run a 30 mm rotor done to 28 mm and you have half
>wore pads, you run a SERIOUS risk of first ripping the dust seal,
>allowing crap to get into the piston bore(s) ultimately destroying the
>caliper from a scratched bore that will no longer seal, and/or the
>caliper piston hyper extending and breaking the inner pressure seal.
>This would cause a failure in brake hydraulic system.

I suppose anything is possible.  I haven't seen it.  Then again, I've seen
more ripped G60 boots from heat with many miles on them (some with just 20 -
track events), maybe a single boot on a Big Red.

>I know... I know... There are many folks out there that are running
>these (and other) setups that are perfect in design. I can only
>ask..."Is the risk worth it to you?

The 993tt uses a 322mm rotor, the braking system was designed for the 993tt.
Does that mean the 993tt can't effectively clamp onto a 300mm rotor, or a
335mm rotor?  Not at all.  Is thickness important?  I think so, but I've also
seen plenty of kits from others that don't, without the failures you claim.
Does that make it right or wrong in design or execution?  Where is the
information that that 2mm is significant?  I'd sure think Porsche would make
sure there were no failures wrt calipers if the customer was beyond wear
limit.  But I don't know.  I just haven't seen what you claim might be true.

>BTW, as I don't sell adapters for any Audis, I have no vested interest
>in this conversation other than I hate to see incorrect info being

Pot calling the kettle?  Hundreds of brake kits on audi quattros.  Some
better than others?  I suppose.  Is a tt caliper clamping a 300mm rotor,
better or worse than the G60?  Michael, look hard at the G60 caliper that
adorns factory quattros from 1986>1998.  With weights from 3000lb to 4200lbs.
 ALL the same.  The question:  Are these also "designed for" the application,
or just handy. Could a compromise to the "ultimate" 993ttcaliper/rotor be
better in all respects than what Ingolstat punches out from the factory?  I
certainly think so.

Your comments wrt drilled rotors applies to wet conditions I suppose,
motorcycles use them.  However, what we don't see Michael, is race cars
switching to crossdrilled rotors for either heat dissipation or wet
conditions.  Why not?  Well, even porsche knows it's vanity, casting holes is
their thing, but most others, accept the vanity, and just give you slotted
rotors, it does the same thing with less heat cracking and less temperature
differentials across and within the rotor faces.

The nice thing is that we have a lot of choices wrt Big Reds on quattros now.
 Carl J and I still smile that we started such a ruckas 6years ago.  All out
of frustration and  intents of selfishness.

Now I'm ignorant?

Well, thank you Michael.

'87 44tq mit 993tt calipers over slotted rotors

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