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badbasser98
01-05-2007, 01:12 PM
Looking for info anyone may have info on what can cause a pulsing brake pedal. At higher speeds it feels like badly warped rotors, at low speeds there is a pulsing in the brake pedal that corresponds to the pulsing deceleration of the car. The pedal will drop slightly then push back against my foot. Is this the sign of warped rotors, or something more serious like a bad ABS unit, or master cylinder? :shock:

enlighten me please...

Huffer
01-05-2007, 01:25 PM
Most likely pads are worn unevenly...

oncesir
02-18-2007, 03:04 PM
Here is the rule of thumb for brake pulsation issues.

Brake pedal pulsates and the steering wheel has a "shimmy" side to side ONLY WHEN BRAKING. This means your front rotors need to be machined.

Brake pedal pulsates w/ NO steering wheel shimmy and a slight vibration can be felt in the seat of your pants only when braking. Rear rotors need machining.

Understand that your speed can and will determine the amount of pulsing from the brake pedal. Usually the faster the vehicle speed the more of a vibration is felt through the passenger compartment and at the brake pedal.

FWIW its unlikely that the rotor gets "warped" due to heat or otherwise. There are lots of reasons why the pedal pulsation develops. Anything from driving habits to cheap brake components(pads and rotors) can be the cause. hth

Sarra
02-18-2007, 06:35 PM
My BE had a pulsating problem with the brakes. I upgraded to a ceramic composite pad, and then "baked" them. Basically, you heat the brakes up by driving while holding the brakes down a little, then do a maximum braking stop. It helps if you have heat deposits on your rotors, sometimes one part of the rotors will get hotter than the rest, and the brake pad material will start sticking to it, metalurgic reaction. Using a different pad will heat it up and then pull the uneven part off. It's not 100% perfect, but it worked for me.

scottzg
02-19-2007, 12:09 AM
track pads are pretty good at fixing pulsing brakes too.

badbasser98
02-19-2007, 11:15 AM
I know what warped rotors feel like. I was trying to confirm that this could also cause the pedal itself to pulse (which I have never experienced before).

I think I have narrowed the problem down to warped rotors... Atleast that is where I am going to start. I have some Brembos on the way and hope those fix the problem.

Huffer
02-19-2007, 11:37 AM
I think I have narrowed the problem down to warped rotors... Atleast that is where I am going to start. I have some Brembos on the way and hope those fix the problem.

Did you check your pad wear? 90%+ of "pulse" problems arise from uneven wear on pads.

badbasser98
02-19-2007, 11:54 AM
Yes, there is hardly any wear on the pads to speak of...

badbasser98
03-02-2007, 11:06 AM
replaced the rotors last night... No more problems, though there is still a slight squeek. It feels great to have smooth brakes again, thank you Brembo.

Superu264
04-05-2007, 10:28 AM
How do I spot warped rotors? :oops: I have some bad pulsing too.

When I have time I'll check the pads but I know nothing about brakes.

Huffer
04-05-2007, 11:27 AM
How do I spot warped rotors? :oops: I have some bad pulsing too.

When I have time I'll check the pads but I know nothing about brakes.

You have to take the rotor off and measure the thickness all the way around using a measuring caliper. Or, if it's really warped, it won't sit on a flat surface well.

Usually the warping is invisible to the naked eye - fractions of uneven wear will be noticeable to the driver.