Brake issues. .

[bumsoil]

For almost a year now I have had really bad brake issues. It all started when I left my front passenger caliper unhooked overnight. Once I hooked it back up and bled the brakes I had a stiff spongy pedal. From that point on my brakes have felt awful. I have bled tbem myself with a pressure bleeder and the conventional way about 10 times and had midas, ford, and a independent shop bleed them. No change in pedal feel.

The issue is there is about 1" of spongy freeplay in the pedal, and the brakes feel as if they are partially unassisted. It's uncomfortable to stop semi quickly because of how much pressure the brakes need.

In a panic stop situation, and I'm talking quick slamming on the brakes not just pushing the pedal hard. The pedal drops almost to the floor, kicks back up THEN the brakes engage/lock up. The delay and lack of controll over pressure is horrid and has almost gotten me into more then one accident.
The brakes will lock up with enough pressure, and if you apply pressure slowly they just feel really stiff and mushy. But the way the brakes behave is unacceptable and dangerous and I'm out of options.

I have all new brake hoses, rotors, pads, baer 6p calipers and have fresh power steering fluid. The master and booster are stock.

 

[2DXTRM]

Narrows down to a few things, maybe something is up with the ABS block? Or something related to the master/hydraboost system.

 

[bumsoil]

Narrows down to a few things, maybe something is up with the ABS block? Or something related to the master/hydraboost system.

If I disable abs it behaves the same, but when abs engages it gets stupid and sometimes locks up one wheel. so idk if abs is effecting it. If I'm sitting still with the car running it acts the same when I slam on the pedal.

 

[bumsoil]

Anyone else have insight on this? could a bad hydroboost cause this type of behavior?

 

[chao5.0]

is it the same wheel that always locks up? the hydro boost is just as assist system, it sounds like you have a problem internally with the brakes hydraulics. the caliper that unhooked, is that the one that locks up? perhaps try bleeding the system with a power bleeder that forces the fluid from the master cylinder to the calipers. I had a problem similar to this with a GTO once with a spongy pedal and basically it was the way the car was bled. the only way we could ever have a firm pedal was if we used a power bleeder.

 

[bumsoil]

is it the same wheel that always locks up? the hydro boost is just as assist system, it sounds like you have a problem internally with the brakes hydraulics. the caliper that unhooked, is that the one that locks up? perhaps try bleeding the system with a power bleeder that forces the fluid from the master cylinder to the calipers. I had a problem similar to this with a GTO once with a spongy pedal and basically it was the way the car was bled. the only way we could ever have a firm pedal was if we used a power bleeder.

Both wheels will lock up, and i have used a power bleeder myself a few times, ford, midas, and muffler shop all used power bleeders on the system as well.

Anyone want to buy a cobra? I'm sick of this crap with my brakes, eventually it will get me in a accident.

i have been researching this issue almost non stop for a few months, and almost every term i search in google brings up a list of pages I've already visited. I'm going to post a video today showing the pedal acting stupid.

 

[bumsoil]

https://goo.gl/photos/46GBG2CZd8Zbinxm7

https://goo.gl/photos/qL2jGYxkAdjCmboVA

its hard to make a video showing the issue.

if i push the pedal down ~1inch then hit the brakes hard they react, but still feel bad. but if i quickly depress it though the "slop" there is a delay between depressing the pedal and the brakes garbing.

 

[2DXTRM]

have you bled the master cylinder

 

[mcaligiuri]

Sounds like a bad master and one seal blew and your using the rear brakes to stop the front

 

[bumsoil]

have you bled the master cylinder

yes, a few times now.

 

[bumsoil]

Im picking up a 2000 540i touring tomorrow, now that my cobra wont be my daily i can fix these issues much more easily.