Brake master fun

[superj]

Right front wheel brake works for a second and then the left front kicks in and pulls the car back left. What a heart attack it is when you hit the brakes.

Found out the car had no back brakes because it failed safety inspection for no back brakes. The fronts worked together till we tried bleeding and had to replace all the soft lines in the back. This lead to having semi working rear brakes and oddly working front brakes.

Which lead to wondering why the pedal is fine if you stomp it but drops to the floor if you have to keep your foot on it lightly. And drops to the floor without activating any brakes.

So, new master is on the way.

[ZeroDarkE30]

proportional valve is still working fine though?

[superj]

yes. now that we have found out there were no issues, it appears to be.

the back soft lines had collapsed internally sometime in the past. who knows how long because it appears they have not worked for the two years the car has been at my house. we were just semi messing with the car, not really intent on making it legal to drive yet but my youngest son wanted it as a daily so we had to start working on it. one inspection place told me the power steering was an issue, so we removed it and then I took it to a buddy to inspect. he said the power steering was no problem but the back brakes weren't working. sure as heck, no back brakes when I had my son drive in the yard and hit the brakes. that lead to the first post.

so, master cylinder should be here by Thursday since no one in town carries it. then, we will start on the fun modifications

[ZeroDarkE30]

Im sure you looked already but look at the caliper pistons and make sure they aren't seized.

[superj]

yes, they are not. I was worried about that but they are good

[doctorx69]

Another thought to check, the abs pump still ok? I am leaning though to the master being toast.

[superj]

I don't know on the abs pump because all the wiring is cut at the wheels. so no abs and no brake sensors. I have to buy new abs sensors and solder new plugs onto the harness ends so I can hook that stuff up. the abs pump looks good and the relay is good but I cannot tell because it has nothing to tell it that the wheels are traveling at different speeds when braking, currently

[mlytle]

hopefully you replaced the front softlines also..........and the rear softlines above the subframe.

i would rebuild all the calipers. ez job and i guarantee if the soft lines were bad, the calipers are full of some ugly brown sludge....like this. brake bleeding/flushing WILL NOT clear this out.


if it was my kid driving it, i would make sure every part of the critical brake system was fresh.

[jclausen]

Bypass it the abs pump

[superj]

I will check it out. you are right, its not hard or expensive to throw a rebuild kit on it.

I wasn't getting brown junk out after I replaced the lines, I was getting black at first and then it went to clear (lots and lots of leg presses by my youngest son, ha ha ha) but I can definitely check it out because I did not open the calipers and check internally. I already know that brake fluid is hydrophilic so there could surely be tons of moisture corrosion in the bores.

[mlytle]

I will check it out. you are right, its not hard or expensive to throw a rebuild kit on it.

I wasn't getting brown junk out after I replaced the lines, I was getting black at first and then it went to clear (lots and lots of leg presses by my youngest son, ha ha ha) but I can definitely check it out because I did not open the calipers and check internally. I already know that brake fluid is hydrophilic so there could surely be tons of moisture corrosion in the bores.

the brown junk won't come out with bleeding. new brake fluid enters top of caliper, air comes out of top of caliper...brown junk accumulates on bottom from years of poor maint/lack of brake flushing. that is why calipers should be rebuilt periodically regardless of how good the seals look.

[superj]

yes sir. I understand. I was just commenting on the colors coming out of the lines.

repairs are on hold for parts delivery. one thing that is no fun about the e30s being so much older now is no one in town carries anything in store anymore. I have to order everything

[mlytle]

yes, the joys of old car ownership! :-)
luckily most all the parts are still available, relatively quickly, from places like FCPEuro.

will be great when the car gets back on the road...with good brakes!

[superj]

Yup, ha ha ha. Brakes are great, ha ha ha

[H.J. 1981]

hopefully you replaced the front softlines also..........and the rear softlines above the subframe.

i would rebuild all the calipers. ez job and i guarantee if the soft lines were bad, the calipers are full of some ugly brown sludge....like this. brake bleeding/flushing WILL NOT clear this out.


if it was my kid driving it, i would make sure every part of the critical brake system was fresh.

Those two softlines above the rear subframe i can not access, the only two hoses on the car that i have not replaced. I did rebuild all 4 calipers with new seals and pistons, as well as a new BMC and brake booster.

[tomstin]

Master cylinder for sure. My guess is the fluid is bypassing the seals (pedal slowly goes to the floor with steady pressure). Since you have the problem, time to replace the soft lines, maybe even blow the hard lines out, and either rebuild or get remanufactured calipers. We talk a lot about making these cars go and handle, but we need to be confident in the braking system.

[mlytle]

Those two softlines above the rear subframe i can not access, the only two hoses on the car that i have not replaced. I did rebuild all 4 calipers with new seals and pistons, as well as a new BMC and brake booster.

ya gotta get those two lines above the subframe. if the other two rears were collapsed internally..the subframe lines are probably compromised also. it is best to drop the subframe completely to get at them (and do the bushings while you are there), but you can drop the subframe carefully an inch or two and get at the brake lines. just do it.....:-)

[superj]

/\ that is the plan