Brake Pedal Vibration

[lcarpen_2000]

The car is on jack stands. I start the car and I hear a rubbing. I have disconnected the clutch cable and put the car in neutral.

When I press the brake pedal I hear a loud rubbing noise and get severe vibration through the pedal. The only thing I could think is that maybe the ABS is going off because the car is on jack stands? I do have a new clutch and resurfaced flywheel in place - but I figure if the clutch is disconnected it should not matter....

Any ideas for me?

 

[Cookieman00x]

There could be air in the lines.. Does it do it when the car is on all 4 wheels?

Sounds like your ABS is pulsing... Is the ABS light on the dash lit at all during this time?

 

[lcarpen_2000]

I have not taken it off of the stands yet. No ABS light. The harder I press the brake peddle, the louder and stronger the vibration is. I think I may take it off of jackstands and test and then disconnect the ABS fuse and test.

 

[WVUAnt]

If you have a brake pedal vibration, you more than likely warped your brake rotors. When severe enough, it can shake your whole car.

 

[Cookieman00x]

If you warped your rotors, you wouldnt feel it unless the car was moving... This sounds like an abs problem because the car is up on jack stands

 

[lcarpen_2000]

ok - I took the car off of the jack stands and disabled ABS. While the card is NOT MOVING - Still have a heavy rubbing feeling and sound on the brake pedal - it increases as the engine speed increases as well. The harder you press on the brake pedal, the more of a rubbing feeling you get - like you are pressing against something that is moving. I am really at a loss - any ideas?

 

[lcarpen_2000]

ok - figured this out. Maybe this will help someone so I am posting my findings. The car has hydroboost brakes. Didn't know exactly what that means until now. There is a plunger that is hydraulically activated by pressurrized power steering fluid. It is inside that big black contraption on the drivers side firewall that the master cylinder is hanging off of. I had not bled my power steering since draining it while I rebuilt the engine. I had just topped off the power steering reservoir.

Turns out all i had to do was turn the wheels from side to side a few times. This circulates the fluid and fills up the hydrobooster! Stop the car, wait for the bubbles in the power steering reservoir to go down and top it off. I did that a few times until the hydroboost was filled up with fluid.

After it was fully bled, I now have no vibration! Crazy how this stuff comes together.

 

[mysicman]

Thats a good info, hadn't thought of that. Glad you found out before tearing everything apart.

 

[jlg32281]

My luck I would have replaced the entire system before actually finding the problem.

 

[RoadZOmbie]

You have good Detective skills. Good ef'n job!