Hi,

My '75 for some time now has had a left rear brake that has been squeaking. It will squeak when rolling down the road. It will then stop when the brake pedal is lightly pressed and come back louder when more pressure is placed on the pedal. I took the brake pads out, cleaned them, cleaned the rotor and the noise stopped for about a month. Now it is back. Do any of these "disk brake quiet" products work or perhaps I should change the pads and/or turn the rotor at this point? Thanks for any suggestions!

Robert

 

Make sure the insulator is in place between the pistons on the caliper & your brake material

 

Yes. The ones that work "cushion" the pistons from the pads. They dampen the vibrations that cause the sqeaking. I've used both the stuff in the tubes, and the stick on rubbery stuff with equal success. (Don't get the stuff on the front of the brake pads...)

Good luck

 

So you are saying brake squeek is more often caused at the piston & back of the brake pad surface? Interesting, I always assumed it was the pad & rotor contact surface.

 

This type of squeak is usually caused by runnout pushing the pads back and forth. The pin that holds the pads in, is the source of the squeak. Its sort a like on of those slate turkey calls.

 

What do you think wears, the pin, the pin holes in the pad or the pin holes in the caliper?

 

I didn't realize that was the source of the squeak. I'll try some good brake quiet insulator and see how that works before replacing any pads. I too thought it was always caused by pad on rotor contact.

 

The pin does not necessarily have to wear to make noise, just rub back and forth in the hole on the pad.

 

The squeak comes from the pad & rotor, but putting cushioning between the back of the pads & the pistons stops the noise from being transmitted to the rest of the system. That way you don't hear it. By the way, the squeak doesn't affect performance.

 

On other disk brake cars, I solve squeeling problems by taking the brake pad out and putting a small bevelled edge on both the leading and trailing edges. That chamfered edge seems to solve my problems. Instead of having a nice 90 degree angle between the horizontal and vertical surface of the brake pad, I now have a 30-45 degree angle. I don't measure it, I just take it to my grinder and eyeball it.

Gary

 

75 Shark
Brake squeel is usually caused by two things. If your brakes are low (worn) there is a small piece of metal attached to one pad (I call it a squeeler) to indicate a worn pad. As the pad wears this piece of metal will eventually touch the rotor and squeel, letting you know you need brakes in the near future. In most cases the squeel will stop on brake application because the pad actually bends a little and lifts the squeeler off the surface of the rotor. This squeel can be heard when cornering without touching the brakes too because of the slight flexing of the related parts. If your brakes squeel when the indicator is not touching the rotor, it's caused by vibration. Products like disc brake quiet and or shims are there to absorb the vibration and stop the squeel and work very well. Sometimes squeel can be caused by an improper pad break in with a new brake job. If rotors are too smooth or if the pads are allowed to get too hot on initial use they will glaze (get a very hard surface layer) and this will reduce performance and can cause squeel. It's important to make sure you have a non directional surface on the rotors when installing new pads and break the pads in using the manufacturers instructions included with the pads. Bendix has (or had) a line of pads that actually have a rough grit glued to the face of the pad to create a rough surface for proper pad break in to make it easier for the guy who doesn't have the means to create this surface easily. If your pads aren't glazed too badly you can sand them (make sure you sand them flat) to remove the glazed portion and re-install them using Brake Quiet or a similar product. And have the rotors machined with a light cut and have the shop put a non directional surface on them while they are at it. Rotors that are machined too thin will heat up very quickly and cause rotor warpage, brake fade and pad glazing so make sure you don't go too thin. In newer cars I replace the rotors instead of maching them because they are cheaper than the older hub and rotor assemblies and you avoid the problems associated with maching rusty heated rotors. Stay away from off shore Chinese made rotors. The American and Canadian made rotors are made with better iron and don't rust as easily.
Maybe a little more info than you wanted but I got on a roll.
JJ