[s-cars] Big Reds Question?

[Linus Toy]

By "which bracket, which caliper" I was referring to the different possible
kits on the market--i.e. ECS, Movit, 2Bennett, etc.  While some use an Audi OEM
rotor (whether for a US-spec or Euro-spec car) others use the 993tt rotor on a
custom hat.  It is this latter config that allows for minor variations in the
placement of the rotor/caliper relative to the hub surface.  Also, some kits
use the 993tt caliper, others use the 996tt (Monobloc) caliper. 

FWIW, the original RS2 rotor was 304x32, under a "small" red caliper as you
refer to it.  The "upgraded" RS2 rotor was 322x32 of the 993tt, under the Big
Red caliper of the 993tt.  Both sizes are stock Porsche rotors--remember, the
RS2 used a Porsche spec hub and bolt circle, 5x130, instead of the normal Audi
5x112.

The 5mm spacer I'm referring to is not to space out the caliper from the
bracket, but to space out the wheel from the rotor/hub surface.  Although both
calipers bolt to the same caliper and use essentially the same size pad (there
are differences), the BR 993tt caliper sits a bit taller than the smaller 993
caliper.  

And yes, the centerline of the BR caliper is a bit off when used with the A8L
rotor--the A8L rotor is only 30mm vs. the 993tt rotor at 32mm.  You can ignore
it like I did (beware of fully worn pads) or machine the bracket a bit to
perfectly center it..

FWIW2, the 314x30 fitment from some kits is a Euro-spec Audi rotor.

 
  _____  
Linus Toy
Mercer Island, WA 
linust at mindspring.com
  _____  



> -----Original Message-----
> From: Richard Tanimura [mailto:richard at tanimuras.com] 
> Sent: Tuesday, January 27, 2004 10:31 PM
> To: Linus Toy; 'Scott Munger'; 'Angelo Alexopoulos'; 
> s-car-list at audifans.com
> Subject: RE: [s-cars] Big Reds Question?
> 
> 
> Angelo,
> 
> I think Linus is right on about the wheels. I think it is a 
> little confusing when he writes "This depends on .... which 
> bracket, which caliper...".
> 
> I think what he means is that some people use the term "Big 
> Red" loosely. Porsche makes a number of calipers in different 
> sizes which are large and painted red. To me, a "Big Red" 
> denotes a specific size. This size was used on different 
> model cars like the 928GTS, 965 and 993TT. Some have 
> different cylinder sizes. But outer dimensions of the caliper 
> itself and the pads are the same size.
> 
> The bracket's job is to position the caliper correctly in 
> relation to the rotor. For any given size caliper and rotor, 
> the critical dimensions of the bracket are fixed. So a 
> correctly designed bracket made to fit the "Big Red" to an 
> A8L (323mmx30) should always fit wheels.
> 
> The "factory" solution is actually just a bracket (Audi PN 
> 8A0 615 125 A). It was designed to fit the RS2,928 S4, 944 
> TurboS, 968 M030 (Little Red) caliper to a Porsche hub 
> carrying a 314x32 Porsche rotor. The "factory" never intended 
> it to adapt the "Big Red" to an Audi hub carrying a 323x30 
> Audi rotor. I think that's why you need the 5 mm spacers (the 
> rotor diameter is 9 mm larger). I think the centerline of the 
> rotor is also slightly displaced relative to the caliper, but 
> when you think of all the factors that are different, it is 
> amazing the thing works at all.
> 
> So if you want perfect centering and no spacers, you need a 
> custom bracket made for a specific caliper-rotor combination. 
> ECS, Movit, BIRA and others have developed such brackets.
> 
> Rich
> 
> 
> -----Original Message-----
> From: s-car-list-bounces at audifans.com 
> [mailto:s-car-list-bounces at audifans.com]On > Behalf Of Linus 
> Toy
> Sent: den 28 januari 2004 01:40
> To: 'Scott Munger'; 'Angelo Alexopoulos'; s-car-list at audifans.com
> Subject: RE: [s-cars] Big Reds Question?
> 
> 
> This depends on who's Big Red setup you use...which bracket, 
> which caliper, etc. If you use the "factory" solution (RS2 
> bracket, 993tt caliper, A8L rotor) you will need to use a 5mm 
> spacer with the forged urS 5-spoke (16x8) wheel.  The 
> interference is in the "shoulder" of the wheel, just past 
> where the spokes meet the rim.  Interestingly, the 16" Avus 
> wheel (16x7.5) will clear without a spacer.
> 
> 
>   _____
> Linus Toy
> Mercer Island, WA
> linust at mindspring.com
>   _____
> 
> 
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