Squeeee! Brake squeal

[Wayne Kever]

My '67 would be more fun to drive if the brakes didn't make that annoying squealing sound. I've read that the factory original pads were much less prone to squealing, but more prone to causing cancer, so they were discontinued. OK, I can accept that tradeoff.

The front brakes have never squealed since I've had the car. The rear calipers were replaced by the previous owner, and squeak on most applications of the brakes. I've had three different shops check the brakes. All are in agreement that they are in fine working order, and that they don't know how to make them stop squealing.

I've seen the various backing strips, plastic doo-dads, and magic goops in the catalogs, but none of the shops has had enough success with those to accept money to put them on. I presume this is because customers are unhappy when it doesn't work.

What works?

- Wayne

[Joe L.]

Re: Squeeee! Brake squeal

Wayne-----

Try this:

First, remove all of your existing disc brake pads and discard them.

Then, obtain a rotor surfacing kit manufactured specifically for this purpose by 3M and of their part number 01410. This kit sells for about $30 and all that you need to use it is a 1/4" or 3/8" electric drill. Using the pads supplied in the kit, apply a non-directional finish to both sides of all 4 of your rotors. Unfortunately, to do this you will need to rewove the rotors from the car since it is nearly impossible to surface the rear side of the rotors with them mounted on the car.

Next, THOROUGHLY clean the surfaces with several applications of non-petroleum-based, aerosol brake cleaner such as that manufactured by CRC or Berrymans(not B-12, though). Also, carefully clean the faces of the caliper pistons to get them as clean as possible.

Lastly, install a set of GM #18024741 disc brake pads. These are non-asbestos pads which replace the original asbestos pads(which were ABSOLUTELY the FINEST pads EVER manufactured for a Corvette). It will require 2 units of the referenced part number to service all 4 wheels and they currently GM list for $58.42 each.

I think that this will solve your problem.

[Michael W.]

Re: Squeeee! Or is it swish?

Wayne,

If I read your post correctly, the brakes only squeal when you actually apply them, not when they are released. Most of the aftermarket thingamajigs only work when the brakes are released or applied very lightly. I used the red plastic fork do-jigger on one of my rear calipers to silence an annoying 'swish' sound only heard when the brakes were completely released.

If your brakes only squeal when applied, I think Uncle Joe has covered it very well.

Mike


Quebec NCRS Chapter

[Wayne Kever]

Re: Squeeee! Or is it swish?

It is definitely a squeal only when applied. Sometimes getting on them harder makes it less or makes it go away, but not all the time.

I'm going to try Dr. Joe's prescription. Thanks, Joe.

- Wayne

[Rob Brainard]

Re: Squeeee! Or is it swish?

Brake squeel is a result of brake pad vibration and the calipers. Resurfacing the rotors probably won't do any good. As supplied by most brake pad mfgrs., disc brake "membrane" is applied to the inside of the pads at the caliper contact points. Letting it throughly dry [harden] is essential. This should take care of your problem.

[Terry M.]

Re: Squeeee! Or is it swish?

Use caution with that membrane you are talking about. Corvette disk brakes use a lip seal to seal the piston to the caliper bore. This design is very sensitive to lateral movement of the brake piston.

Most other disk brake systems use a square cut O-ring to seal the piston. This design is much less sensitive to the movement of the brake piston.

With these membranes you are glueing the pistons to the brake pad backing. Thus as the brake pad moves, so does the piston. The square cut O-ring can tolerate that movement, but the lip seals in the stock Corvette system can not.

I think you are asking for trouble trying to fix the noise with these "band aids." Joe is on the right track with his advice. The correct pad material and a properly prepared disk surface are essential to silent braking.

Terry

[Terry M.]

Re: OOPS (sorry reat too quickly)

Back to school for me. I mistook your suggestion for a different product. I see you are talking about an application at a different point on the system, one with which I am not familiar. Sorry.

Terry

[Joe L.]

Re: OOPS (sorry reat too quickly)

Terry-----

Actually, I agreed with your first response for exactly the reasons you stated. I'm not a believer in placing ANYTHING between the caliper piston and the disc brake pad backing plate. Just as you stated, the piston seal used on 65-82 Corvettes was different than most other disc brake systems of the period. This seal is called a "chevron" seal. In my opinion, with this design, the piston must be totally free to "float" on the pad backing plate. That's why I recommend that the pad backing plates and the piston faces be very clean in order to facilitate this "free movement". Anything that causes the piston to "grip" the pad backing plate could cause the piston and the seal to be side-loaded, impeding the effectiveness of the seal.

[Terry M.]

Re: OOPS (sorry reat too quickly)

That is exactly what I was saying, but as I went back and more carefully read Rob's post I believe he was talking about puting some kind of material elsewhere on the caliper. Maybe I am wrong about what he ment, but I am absolutley sure making the pistons stick to the brake pads is a recipe for major leaks.

It MAY quiet the brakes briefly, but not worth it.

BTW: Some minor noise (the bounding of the pads against the pin as the car goes over bumps NOT included) on application is normal for this design. They are not completely silent, even under the best of circumstances. Terry