Brake problem after recent install

[90turbotsi]

Not too long ago I upgraded all of my brakes on my 90 TSi AWD. I went from the stock setup to the larger 92-94 calipers with new stock calipers in the rear and TPM/Racing Brake drilled and slotted rotors with EBC green stuff brake pads. However since the install it seems that whenever I am in the 1500-3500 rpm range while braking there is something noticeably wrong. The braking power is obviously not what it should be and the whole car vibrates. It is obvious that it is coming from the brakes, I am just not sure what it is. It almost feels like I have slammed on the brakes with ABS, which my car lacks. Any input as to what is wrong would be greatly appreciated as I just want my car in top driving condition.

 

[wret]

This is a little confusing because braking has nothing to do with engine speed, only vehicle speed. Other than that it sounds like you have excessive runout on one or more of your rotors. If you lack the skills and equipment (dial indicator) to test for it, you should take it to a brake shop.

Can the vibration be felt as a pulsation through the brake pedal?

 

[90turbotsi]

There is a slight pulse feeling and noise to it. It does not feel like warped rotors do, more like a pad is out of place or something...however its not. Ive heard of some problems with the EBCs in the past but being soo new I dont want to think its them. Similarly the rotors are/were new so its hard to say its them. Its the fronts for sure, i have rulled out the back brakes which makes me wonder if a caliper is bad. Considering they weer purchased used im not sure. I can have it looked at but I do all my own work and hate paying out the a** at the shop... plus it seems all the shops around here have no idea what they are talking about and I get into agruments with them.

 

[90turbotsi]

I dont find it to be noticed at higher speeds only when car has slowed for a bit. Often if I get off the brakes and tap/get back on them it goes away or settles out a good amount.

 

[wearurpjs]

sticking brake piston perhaps...? sounds like it may be out a bit and causing some drag...although I dont think it would be enough to cause a vibration...

 

[jtmcinder]

Sorry, Ron, but there is a link between engine speed and braking: via the vacuum assist. If, for example, the EGR is fluctuating at those rpms, then the vacuum is fluctuating, which could very well feel like at the pedal like ABS kicking in.

- Jtoby