88-5kq - Girling rear brakes- Can 38mm be used in place of 36mm?

[kbogach]

Sylvester, 

I am not sure you want to use 36 mm calipers but:
there is nothing there to jam the piston at the very top if it came 
almost all the way out.  Top of the bore has usually most of the rust, 
but you were able to turn the piston almost all the way out.   The only 
thing I can think of is that bottom of the piston has some rust too and 
it binds with rust on the top of the bore.  But I never saw rust on the 
bottom of the pistons on those 6 calipers I had rebuilt.   I would 
remove the boot (vary carefully), put the top of the piston in vise 
(grab piston above the groove for the boot)  and try rotate the 
caliper.   Of course I would do it only if using a good tool for piston 
removal did not help.  Use lots of brake fluid as lubricant but I am 
sure it is plenty left inside the caliper anyway.

Konstantine

SJ wrote:

Message: 4 Date: Fri, 07 Apr 2006 21:19:36 -0400 From: SJ 
<syljay at optonline.net>
Subject: 88-5kq - Girling rear brakes- Can 38mm be used in place of 36mm?
To: quattro at audifans.com Message-ID: 
<000f01c65aaa$80284220$b214c444 at dell450> Content-Type: text/plain; 
charset=iso-8859-1

 The 100q has a dragging rear brake. Its not the cable, its not the 
lever. The piston does not return to its non-parking position.Must be 
something corroded on the inside. I cant remove the piston to check out 
the insides. I got it turned out almost all the way out, and now its 
jammed. I took off a caliper off my 5kq(layed up for exhaust, bomb, 
bushings) and installed it in the 100q. Works ok. The 88 5kq uses 36mm 
rear calipers. The 90 100q uses 38mm rear calipers. Family album says 
both cars use the same brake caliper - 38mm. Duh!!!! Both size calipers 
are interchangeable mechanically. Can I use the more popular 38 mm in 
place of the 36mm? It might give me a bit more breaking in the rear. 
But, since the proportioning valve is probably corroded and jammed, I 
dont think it makes much difference if the rear caliper is a 38mm 
instead of a 36mm.
SJ
85 Dodge PU, D-250, 318, auto
85 Audi 4k - - sold but still on the road
88 Audi 5kq
90 Audi 100q
--