Big Red Stuff

[QSHIPQ@aol.com]

Mark Nelson writes:
>A 12.5" rotor will not work with 15" wheels...only "thin" 16" or 17" wheels
>will clear it.  Stay tuned as more details are coming shortly.

>cya!
>-mark nelson

Having btdt on the Big Red Conversions for a couple years and several audis,
let me help out here:

A 12.5 rotor will just fit in most 16in wheels, but watch the offset and the
manufacture, it's still tight in there.  My experience with the Big Reds is
that the problem isn't usually rotor clearance, but caliper clearance, which
has more to do with the manufacture of the wheel and it's offset.
Specifically, it's the lip and the spoke design of the wheel itself.  Many 17
in wheels are a "stretched" 16 (or even 15), which means there is a step on
the inside of the wheel that can whack the caliper.

For instance, the Groupe A (ex FIA - '95 S2) car that ran last week at Lake
Superior PR will take a SQ specified 15in steel wheel with the sport quattro
brakes.  But, when we changed to ABT 16in wheels for the tarmac stage, the
caliper was so close to the wheel that after the first tarmac stage, we
changed the RF because of caliper rotor grinding.  When we changed it, the new
spare wheel still got ground down as the car pulled from service.  So, don't
automatically assume that a wheel tire combo will clear a specific brake.  

Regarding the Big Reds specifically (and this will apply to the 928 as well).
The Big Reds are designed for a 13-13.5in rotor.  Going to a 12.5 in rotor
means you have to regrind or buy special pads, because the pads won't fully
cover the swept area of the rotor.  I have yet to have a set of 17in wheels
NOT clear the caliper, but many wheels get REALLY close (for heat purposes,
closer than 1/8in clearance on a brake component is getting critical)

Bottom line:  "Bolt on" is relative to the wheel and offset of the wheel you
plan on using.  My suggestion is that if you are looking to do a brake
conversion, hold off on buying the wheels untill you know they will work with
what you are doing.  Me, I don't automatically "guarantee" all 17in wheels to
fit Big Reds.  But I can guarantee it to be the minimum requirement as far as
wheel diameter.

Brake mods are great upgrades for quattros.  Unfortunately, in the race for
bigger wheels, the tolerances and production differences between them, not all
wheels of the same diameter will fit those upgraded calipers and rotors.

HTH

Scott Justusson
QSHIPQ@aol.com
'87 5ktqwRS2
'84 Urq