Re: 5000s brake woes

[ewendell@iolinc.net (Wendell, Edward)]

Because of my inquiring nature and the fact that I would like to spend
as little as possible on expensive Audi parts, I applied some
troubleshooting techniques before replacing anything when I had brake
locking problems.
	 The first thing that I would do in your place is bleed the brakes and
see if you have any pads left. If your sister got the brakes hot enough
to smoke, the brake fluid probably boiled big time and the pads may be
shot as well. My guess is that the spongy pedal and poor braking is due
to air in the lines resulting from the brake fluid boiling. This is
probably also covering up the locking problem because you are not
applying much force to the calipers, just compressing the gasses in the
lines.
	If bleeding gets the brakes back in action, its time to grab a line
wrench and take a test drive. In my case, I had to go quite a distance
in the heat of the afternoon to reproduce my locking problem. When it
occurred, I turned the car off, put it in gear (or park, don't know if
you have an AT) and popped the hood. I then used the line wrench to
loosen the fittings where the brake lines attach to the MC. Brake fluid
squirted/sprayed out and I could feel the brakes release because the car
immediatly moved a few inches until the slack in the drive train was
taken up. This meant that either the MC or booster were causing my
problems because with no pressure on the pedal there shouldn't have been
any pressure in the brake lines. Also, relieving the line pressure
released the brakes, meaning that the calipers were releasing properly.
My next step was to reproduce the locking problem again and this time I
undid the two bolts that attach the MC to the booster and seperated the
MC and booster by about an inch(there is plenty of movement in the brake
lines to allow this). In my case, the brakes stayed locked, meaning that
I had a sticking MC. If the brakes had released, it would have meant
that the booster was pushing on the MC without the brake pedal being
depressed or that the brake pedal was not returning all the way.
	After driving around for a couple of weeks with the line wrench in my
center console so that I could get the car to roll again each time I
used the brakes, I got enough money together to order a brand new Ate MC
from The Parts Connection for $89 and installed it. Problem solved.
	Something to watch out for: if you haven't messed with brake fluid
enough to find out he hard way, be forewarned that the label on the
bottle isn't kidding when it says that it will remove paint if given
enough time. I kept a jug of water handy to wash off the brake fluid
wherever it landed. Brake fluid is water soluable so this works just
fine.
	If any of this info seems elementary or redundant to you I apologize. I
haven't been on the list long enough to have an accurate picture of your
experience and abilities. I would appreciate hearing about your final
fix so that we can add it to the collective knowledge base.

HTH

Roy
86 5000cstq aka "the basket-case audi"