Phil, UrQ brakes?????

[quk@isham-research.demon.co.uk (Phil Payne)]

In message <34AF0712.AD0EC703@cat.hcp.net> 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.
> 
> I'm still having no brake peddle when my UrQ is running.  The peddle
> stays firm when the car is off.  When my UrQ is running,
> the peddle goes smoothly and straight to the floor.  With less, but
> constant foot pressure, the pressure goes 3/4 down, slows,
> then goes the rest of the way to the floor.  The peddle feels like it
> pulsing as if being pushed through the cylinder.

> One more thing, right after I first finished the brakes with the
> original master, I drove my car around the block.  For a half block the
> peddle was firm and then starting going to the floor.  I keep hoping
> it's something simple that I have over looked.  But as time goes I
> feeling its not something that I have over looked.  Also, I had the same
> problems with both the original master and the 200 master.  Could the
> original master have gone bad and I picked up a bad 200 master?

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