Phil, UrQ brakes?????

[Mike Arman <armanmik@n-jcenter.com>]

>Subject: Phil, UrQ brakes?????
>
>In message (snip) Chris Tucker writes:
>
>> Not sure if you caught my last note to the list, but I'm still having
>> brake problems.  Unfortunately the bleeding order was
>> not the problem.  So far I've upgrade the master cylinder to a 200Q and
>> have rebuilt the hydraulic booster.

(snip)

>
>Assuming there are no gross problems (like Pentosin in the brake fluid, or a 
>brake fluid leak) then I'm puzzled.  Bad masters is indeed my first thought, 
>but it's quite a coincidence.  Have you checked the swept volumes
(compared the 
>diameters of the masters in the applications) between the original
ur-quattro 
>and the 200 masters?  There was a diameter change (and hence a volume
change) 
>at one point.
>
>I'm going to have to throw this one open to the floor - it's beyond my 
>competence.
>
>- -- 
> Phil Payne
> Committee Member, UK Audi [ur-]quattro Owners Club
>

Chris - you're DOOMED! If Phil says he doesn't know, there IS NO ANSWER!!!!!

Seriously, I'd look at the "new" replacement master cylinder. I did a
clutch master (rebuilt) which had the same symptoms - good for three blocks
and then died.

I suspect the bore was out of round or the rubber seals were incompatible
with the brake fluid or something equally esoteric. Replacement with a new
cylinder cured the problem at once.

Doubt that the ID change on the MC would make that much difference - effort
would change, but the brakes would still work.

Best Regards,

Mike Arman