Brake Bleed Q:

[Huw Powell]

> During the re bleed of the rears, following the Bentley which outlined the 
> typical RR, LR, RF, LF format I found very little fluid coming out.
> 
> I used a pressure bleeder which was sort of a problem in adjusting the RR 
> caliper piston back out to the pads on the rotor.

It takes braking action to rotate the piston back out to the correct 
position (until then, you get little or no rear brakes).  A bunch of 
roll back-and-forths braking at each change should do it in the driveway.

> So my Q's are:
> 1:  Is there an additional step I'm missing with the ABS controller not 
> allowing fluid to "pour" out when I crack the bleeder screws?  This is on the 
> rears..........

That shouldn't matter (ABS should allow full flow unless it activates)

> 2:  MC the issue?

Maybe, if there is an issue yet.  The proportioning valve for the rear 
brakes allows a lot less pressure through than to the fronts, making 
pressure bleeding a bit trickier.

> 3:  Does the piston have to come out to replace the piston boot?

Don't know...

> I never touched the fronts, and drove the car back home to finish work on it 
> ( no new rear pads) 10V avants' fit though...................Good but spongy 
> brake pedal.
> 
> I considered the fronts and rears to be on different circuits as there are 
> two steel lines from the MC to the ABS.
> (Did they do away with the diagonal braking system the old 5000's had?)

The fwd cars have dual diagonal circuits - LF/RR & RF/LR.  prop valve 
down by rear axle.  Quattros don't, I guess it wouldn't work right with 
the all wheel drive system, so they are dual - front & rear.  prop valve 
right next to master.

> Other considerations:
> Ebrake cables loose to console lever.  (Need adjustment) 

Until the pistons are turned back out the ebrake won't work right, I think.

> Mid Atlantic car no corrosion on any component except the caliper cast 
> surfaces......

Jealousy.  The only thing not rusting around here is the school bus half 
buried behind the building....

> Rear (RR) pad wore inner and out, rotor is a tad thinner on the inside 
> (thickness) outside looks new.

I thought you were getting metal on metal grinding?  That usually scores 
the heck out of the rotor, requiring turning or replacement.  maybe you 
were lucky... did you measure its thickness?

-- 
Huw Powell

http://www.humanspeakers.com/audi

http://www.humanthoughts.org/