I have 1990 civic dx wagon with a Fastbrakes 11 front kit with the new Stoptech street performance pads. The master cylinder, booster, lines, proportioning valve, calipers, drums, wheel cylinders, and shoes are all new. The problem is when I lightly apply the brakes there is a little shake in the wheel and it goes away as I increase pedal pressure, but if I cram on the brakes they work great and there is no shaking. I have no idea what is causing this, and as you can see I have replace everything. Anyone have any ideas?

 

Rotors??? What condition are they in?
Wheels? are they balanced?
Check the front suspension and wheel bearings.
Did you bed in your pads?

 

Im saying rotors... but mine actually got worse with pressure... so ???? I had cheap cross-drilled and slotted. Shaking stoped after I replaced with OEM brembos.

 

Rotors are new from Fastbrakes. I checked the bearings, bushings, and ball joints, and they didn't appear to be bad. I bedded the pad using the directions on Stoptech's website. I think this could still be from pad material deposits. I guess I may have to throw parts at it (bearings, ball joints, and bushings) and see what happens.

 

Could also be the tires? Lightly pressing on the brakes would only move a little weight onto the front tires and depending on the cupping or scalloping of the tires you could be putting enough weight onto the tires to cause you to slow down on the bad section of your tires. And if you brake hard enough you by-pass the cupping/scalloping.

 

Tires are pretty new, and look good. One thing I have noticed is in the morning when the car is cold it doesn't shake for the first few stops.

 

If you have another set of wheels/tires that fit, you could try swapping them on, just to eliminate the wheels/tires as a source of the vibration. (I doubt that it's the wheels/tires since it's only while braking, but hey, swapping is easy.) Otherwise...

That would be my guess as well.

You could try bedding them again. Sometimes that helps. And it's an easy thing to try, no mechanical work needed.

Otherwise, you could try turning the rotors (shaving off as little as possible) or replacing them.

 

Use a dial indicator to check run-out on disc.

Likely pad deposits. You can use 80 grit sandpaper to go over the discs on both sides(as per Hawk brake tech support, will not cut into metal they said).

A better solution is to use a flex-hone (as per AP Racing) or Scotch-Brite and much elbow grease.
http://www.flexhone.com/

 

I concur - if the rotors are new, but the brakes still feel like the rotors are warped, it is probably pad deposits (did you ever use another mfr's pad compound with these same rotors?). I use a wire wheel to get a clean, deposit free rotor surface and then bed the pads again. Never had a brake shimmy I couldn't resolve thusly as long as the rotors were flat.

 

I use Fastbrake 11" HD rotors. I had a problem similar to this with Hawk HP+ pads. I was probably getting pad deposits at the track at track temperatures. I cleaned everything, for deposits, as already noted. I spoke with Brian at Fastbrakes and found him helpful.

 

Im going to lightly sand the rotors with 80grit as mentioned above and try a set of standard brake pads I have. This should show if the shake was from material build-up or something else. Thanks for all the help so far.

 

I did what I mentioned above today, and the only thing that changed is the frequency of the shake. For example It was like 30Hz before and now with the stock compound pads it's like 75Hz, this is the best way I could describe it. Anyone have any ideas????