Brake problem

[vader87gn]

Hello, I have a 86 grand national and I'm having brake problems. I converted the brakes to vacuum brake booster system a year ago and now im having a problem with the brakes going to the floor. I've changed pads, cylinder, rotors, proportioning valve and bled the brakes multiple times and still getting air in the lines. Could this be a bad brake booster or brake master cylinder? How could I test them to make sure they are bad before getting new ones?

 

[TexasT]

If the pedal is going to the floor, you have a leak of some kind. It could be a caliper, rear shoe actuator, or internally in the master cylinder. If you aren't seeing fluid on the back of one of the wheels, my money is on the master cylinder.

 

[vader87gn]

Ok I have changed the master cylinder and I notice I'm getting bubbles in the master cylinder reservoir and the pedal still goes to the floor, what are the odds the brake booster is bad? Or could I just be missing something somewhere else

 

[vader87gn]

Or could I be doing the bleeding process wrong

 

[ek02]

Did you bench bleed the master cylinder?

 

[vader87gn]

Yea I bench bleed it first, I drove the car a good distance and the brakes seemed to work better once I got going, no problems stopping or anything. The pedal seems to just go to the floor while its parked. Is it normal for the pedal to go the floor in park but not while driving?

 

[TexasT]

no

If you are buying remanned master cylinders it is time to switch part houses or step up to new. The mc or some part of your hydraulic system is leaking if it is going to the floor. When I bleed, I like a helper that can follow directions and a block of wood under the pedal so said helper can't over stoke the mc. I still have my money on a bad mc. the pedal should compress until the pads/shoes contact the disk/drum and stop. Brake fluid doesn't compress so if it is going to the floor something is leaking or a hose(s) are really stretching.