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Discussion Starter · #1 ·
Ok, it's a 94 TT 6 speed. Trac eliminate was done, other than that the entire system is stock (lines, calipers)

Problem is the brake pedal feels normal on initial hit, but fades about 1/2 way down then stops and is as firm as it's supposed to be. On first thought, it's air in the lines, so bleed them....right! No change at all. Fluid is max. I can almost feel the back brakes fade away when the pedal fades. When the pedal stops 1/2 way down the fronts are 100%, rears are basically 0%.

I've bled plenty of brakes but these are not right. Just tried to bleed them again, and there is no pressure going to the back brakes!?! Car off, pump pedal and it does not feel right. Pressing on pedal hard, open rear bleeder, and nothing...just dribbles out. Fronts bleed as should. You can tell by the wear on the rear rotors that the back brakes have not been working correctly for some time.

Master cylinder?
Something to do with the Trac removal? (although I've done this to 3 other cars with no issues)
Brake booster?
Crushed rubber line?

Any help or advice is appreciated.

Thanks,
Alex W.
 

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Discussion Starter · #3 ·
That would explain the imbalance, but not the fading. Plus I don't think I've ever ran into a bad Proportioning valve.

Alex
 

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Discussion Starter · #6 ·
That ABS info is good. I'll check that out for sure. I'm very sceptical about the proportioning valve only because I've never had one go bad. I'm hoping it's nothing to do with the ABS modulator (expense reasons mainly).

I bled these the same as all others I've done. I'll go borrow my friends vacula and try again, although I feel the main purpose for that tool is single man brake bleeding. If the force of a person pressing on the brake pedal forces no fluid out, then I'm sure a hand pump cannot draw fluid. Either way I'll try it and see. I'm going to disect some more things in the mean time.

Its been a problem for a while, just never bothered me enough until now.


Alex
 

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Discussion Starter · #9 ·
If you end up needing a new ABS unit let me know. I got a perfect one sitting here collecting dust !

SWEEEEEEET!

Well, times up anyway. I have to go back to work and I'll be out flying around for the next 6 days. I got my hands on a sick power bleeder that BMW uses. It's a big closed loop system with some weird bleeder screws that need to be special ordered and it uses blue brake fluid. That will surely solve any and all bleeding issues that I may or may not have. Then we'll see after that.

Later,
Alex W.
 

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Discussion Starter · #12 ·
Al, I think you are correct. The symptoms seem to lead me to the master. I "think" the power bleeder will bleed the master as well. If not please tell me, that way I can bleed the master first. I'm looking forward to having some nice tight brakes again....in all 4 corners. Either way I will let you know how it works out. I won't be home until Tuesday Evening so I have to wait :(.

Mark, the power bleeder belongs to Tulley BMW in Nashua. A close friend works there and it took some convincing to let me borrow/use it. Not to mention he's going to be there when I do it. I don't think he wants to go to Manch. I'll ask and see. He has to order the special fluid and bleeders for my car, so if he says yes it's about $45 for all the stuff you need.


Alex W.
 
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