Subject: Hanging rear caliper

[Phil Rose]

At 12:32 PM -0700 4/16/05, Bernie Benz wrote:
>Hi Chris,
>
>This load sensitive proportioning valve senses the static position of the
>driver's side trailing arm of the rear suspension.  It is ahead of the Tee
>which distributes the same hyd press directly to both rear calipers.  What
>is this "big cylinder with a moving weight" thingabob?  Are you maybe
>thinking of a hydraulic Citron, not a 44 chassis Audi?

Nope, it's been lurking there on your car all these years, Bernie! ;-)

Actually this valve was something I first encountered last year when 
I needed to replace a badly corroded brakeline coming from the left 
rear caliper (return line). This brakeline goes to passenger side by 
way of a sharp u-turn into this mystery valve--the one with the big 
internal sliding weight. This valve and the plumbing are located 
about dead-center and face to the front--making it hard to access and 
not especially easy to see until you try to follow the path of the 
rear brakelines from side to side. As Chris says, the function of 
this valve is claimed to be sensing hard turns so as to prevent right 
rear wheel lock-up. Not sure why hard turns in only one direction 
were singled out for special anti-lock attention by Audi's 
overengineers.

Phil

>  > From: c1j1miller at aol.com
>>  -------------------
>>  There's a load sensitive proportioning valve over the left rear; then
>>  the line runs across to the right rear. Part way there it goes into a
>>  big cylinder with a moving weight that is supposed to keep the right
>  > rear from locking under a hard corner. Perhaps that is stuck?


-- 

Phil Rose
Rochester, NY
mailto:pjrose at frontiernet.net