Zwoobah

my rear wheels get absolutely filthy in much shorter time periods than they should, while the fronts stay very clean. and the car does not stop well. If I really slam the brakes hard, the car does exhibit some brake dive, and there is a small amount of brake dust on the front wheels, so I believe they do work to some extent. but in normal driving, I think it's just the rears that are working.
I have not yet bled the brakes, and they need it badly. the fluid is molasses color. planning to do that on friday when I swap over to the snowtires. but this seems to be more of a problem than that will fix.
maybe the proportioning valve is shot? any other things to look at? thanks

UrS4boy

corrosion in the caliper pistons. You could also have a siezed rear proportioning valve that is giving too much bias to the rear brakes.

I really think that you should not drive your car until you get this fixed.

4Driver4

Agreed - also make sure you have the correct master cylinder.

S4-Fireblade

... with your reservoir fluid cover mod? I haven't tryed that yet.

4Driver4

Hardly anything - maybe 5 psi. It doesn't take much. Just keep watching the level.

kday

I used 10 PSI with my Motiv I think. Probably 15 when I was trying to figure out why the rears were bleeding so slowly!

Zwoobah

for a car that was owned by an audi tech, this thing sure wasn't maintained all that well. The scary thing is, nick and I drove it from Milwaukee to Boston as it is now. It'll stop alright if you jump on the brakes, it's just under light braking that the rears seem to be doing all the work.

Anyway, I've always had good luck with the two-man brake bleeding system (I don't own a pressure bleeder). Will that work on these cars? I do know what I'm doing, I used to bleed the brakes in my old GTI every morning at the track. Also, is it obvious how to jam open the prop valve? Thanks

kday

Here is a shot of the pressure regulator for the rear brakes. With the drill bit in place the valve should be open. You don't need to do the other steps just to wedge it open, but if you're questioning the bias it'd be worth adjusting it to spec while you're at it.

<a href="http://www.boost-instruments.com/propvalve.png"><img src="http://www.boost-instruments.com/propvalve.png"></a>

You can borrow my pressure bleeder if you want.

S4-Fireblade

Thanks. I'm performing that task tonight.

S4-Fireblade

...lifted on jacks, isn't it?