Front brakes grinding on gradual stops

[Okiesnake]

I have about 1,500 miles on my Unique. I have the upgraded 4 caliper Wilwood brakes in the front. The brakes work fine when stopping quickly. However, when coming to a slower gradual stop at a traffic light, the front brakes sometimes make a grinding sound and vibration similar to when brake pads are worn down excessively. This sound only comes in the last 20 to 30 feet before stopping. The pads are not worn down and the rotors are smooth and shiny. I’m not getting any pulling to one side or the other. Help.

[Dirt Cowboy]

Do you mean 4 piston calipers? I have the Billet Dynalite's on mine, WIL 120-4998. These are the calipers WITHOUT the bridge bolt, just a long cotter pin. The pads make some noise because of pad movement. I got some small springs from the local parts store, a couple of small washers, and new cotter pins. I put the spring in between the caliper pads and they quieted down. No noise now, give it a try.
Later,

Spongebob Squarepants

[Cobra20646]

My Unique does this too..... but from the rear brakes
Anyone have similar problem? What was your fix?
- Jim -

[Cobranut]

I have the Dynalites up front and Girling's in the rear.
I've never had a problem with squeal or grinding noise of any kind.

Dirt's idea sounds valid, just be careful to use a light spring. You don't want the spring to gradually push the caliper pistons back, as it could result in a soft pedal when you first apply the brakes.

Another thing, what pad compound are you using? Many aggressive race pads are very noisy, and they aren't suitable for the street as they need to be warm to work properly.
I'm using PolyMatrix-D's and they are smooth and quiet.

Good luck,

[chopper]

Assuming that there are no malfunctions in the calipers (loose mounting bolts, etc.), I have a suggestion. The replacement pads which I used to get for my old Vette came with a small tube of red goop, which was spread in a thin layer on the rear side of the pad backing plate and allowed to dry before installing the pads. The material formed a semi-rigid film which then sat between the backing plate and the piston, and absorbed the small amplitude vibrations which cause the noise. If I'm not mistaken, this stuff is sold in most parts stores and speed shops.

[427sharpe]

Brake squeal---just get a scotchbrite disc and lightly buff the friction surfaces (pads and rotors) and reseat the pads. Problem should go away. Avoid 'dragging' the brakes for the first 500 miles or so--stop sharply; meaning no panic stops, but firm pressure to help the pads seat without glazing.

[Coloradocobra]

My Wilwood kit came with shim/washers to center the calipers on the rotors and to take care of any "angle" between the caliper and rotor. Take a peak and make sure the calipers are tracking properly on the rotors. If they are cocked, it could cause the pads to shudder a little on light braking. An old trick that sometimes helps is to grind a small 1/8" chamfer on the leading edge of the pads. Are you using Wilwood rotors? My setup uses the heavier Granada rotors.

Gary

[Okiesnake]

Yes, I did mean 4 piston calipers. They are Willwood rotors.
You all have given me good input. Unfortunately it will probably be after Thanks Giving before I get a chance to investigate the great advice. Allen at Unique also suggested that I might need to try softer brake pads. The ones that are on it are a little more suitable for the track. After I figure out the fix I’ll post the result.

However, please keep the input coming!

Thanks everyone,
Okiesnake

[Okiesnake]

I'm convinced the problem is due to the hardness of the pads. The problem has seemed to have gotten better though.
Like 427Sharpe suggested, there may have been a slight amount of glazing.