stiff pedal...change MC booster pads and rotors........

[318driver]

and its still stiff. haha

heres the current situation. I bought the car, knowing that the brakes did not work, i was told by the owner that it was the booster and that did seem the case, brake was rock hard and didnt do anything.

changed
new/used brakebooster and MC, new pads new rotors.

first put on MC w/o bench bleedng and pumped the brake alot, brake went down pretty fast and didnt bleed at the wheels.

then was told that i needed to bench bleed it. i then took it off, bench bleed it correctly, put it on, brake is hard again. loosen bleeder screw, brake still hard, now fluid coming out. tried all wheels. tried taking bleeder valves off and using a pick to clean it out, still nothing, brake rock solid.

then followed the 2 lines from the MC to the abs pump(i blieve its ABS), loosend the 2 lines going threw, and bleed it there, fluid did come out, tightend screws, should be fine.

then loosened the 3 lines coming out of the abs pump, pressed brake, and it was solid with nothing coming out of the ABS pump.

is this where my problem is at? did pumping the brake earlier w/o benchbleeding put alot of air inot my system maybe? what should i try next?


thanks,
desprate andrew

[Mike325]

Sounds like the ABS pump is no good. So no fluid comes out at the wheels?

[318driver]

nope no fluid coming out at the wheels. i loosened the brake hoses at the calipers today,both one at the front and one at the back, and got no fluid, and still a stiff pedal

[Mike325]

So no fluid out of the abs unit, but the fluid will go to it. Sounds like the abs unit is messed up. Is the pedal rock hard, even when running?

[318driver]

yup the pedal moves about an 1inch down, even when teh car is running.

im thinking of getting rid of the entire ABS system and running straight lines

[Mike325]

That sounds like a good idea. Does your abs work anyways? I guess you don't even know because this car has never had good, working brakes for you.

[318driver]

don't even know because this car has never had good, working brakes for you.

[etxxz]

I must revive this thread beucase i might be having the same problem and need it fixed as soon as humanly possible.

My car breaked wonderfully before my 24v swap. Now i run a 735booster, 525i (m50) MC. Bled system and my brake pedal is STIFF!!! i can drive on the street, but it won't brake hard no matter how hard i push it. I've always had an abs light on, abs never did work so could i be having the same problem?? i have a drifting even in two weeks, brakes are a MUST. help asap pleeease.

thanks!
-etxx

[Mike B.]

Did you have the ABS light on prior to the swap?

[etxxz]

Did you have the ABS light on prior to the swap?

yes. what do you have in mind?

[Mike B.]

I was curious to see if your wiring was an issue in terms of powering the ABS pump.

But now that I look at your post, I don't think you are running the right master cylinder

Now i run a 735booster, 525i (m50) MC.
-etxx

You need the M5, 735i or 325ix master cylinder with this booster.

[etxxz]

^^ i am...atleast i think so. At my u-pull-it, I discovered that the e34MC is exactly the same as the 7-er and M5 (never seen an IX)...i actually took both from the junkyard, but i stripped the threads off the e32 MC. same threads, same size and bolts the same way. could this be the problem?

[Mike B.]

I stand corrected... They are the same master cylinders. From Pelican Parts:

34-33-1-156-978-M4
Master Cylinder, Girling, 525i (With M20 Engine)(1989-90), 525i/Touring (With M50 Engine) (to 09/91), 535i (1989-92), M5 (1991-93)
Brand: Ate [Photo]

Now, did you put a new o-ring on the master when you installed it? Are you getting any vacuum leakage from the booster?

[etxxz]

^^ yep.

would vacuum leakage at the booster cause this? i thought it be the opposite, but i did replace the o-ring and the intake mani vacuum connection seems okay. the engine runs well enough to suggest no vacuum leak here. what else could it be.

[Vedubin01]

a leak will from the booster will cause a hard pedal.