Posted about this in my build up, but no one replied so i'm reposting in its own post. So I installed new pads all around about 6 months ago. They were working great up til about a week ago. Now occasionally the pedal will go half way down and vibrate, then shoot back up and give me a tapping sensation. The truck doesn't vibrate when this happens, all the feeling is in the brake pedal. The fluid level stays the same and all my pads are still fine. Has anyone ever had there master brake cylinder surge before going out. any one have any input or ideas? thanks.

 

It sounds like warped rotors to me.

 

there alil grooved and are due for replacement, and this is what I would have thought, except its not consistant. this happens at random throughout my 150 mile drive everyday....

 

It will depend on the speed you are going and how much brake you apply, if you are going slow or stomp on the brakes, you aren't going to feel it like you will going 60 mph and lightly apply the brakes. Your master cylinder will typically be good or it wont, it wont move your pedal up and down like what you are describing, at least I have never heard or experienced this. A malfunctioning ABS pump can do it, if your truck is even equipped with ABS, but I would start with replacing or resurfacing the rotors first, easiest and cheapest and you say you need it anyway.

 

You say the brake pads are fine but the rotors are shot!!

If they are that bad may as well figure on new pads when replacing the rotors.

Sounds like warped rotors and perhaps a caliper hanging up hard to tell without first hand feel