What makes brakes squeak?

Q: Why do my brakes squeak? My Toyota has disc brakes in front and the rear. The disc brakes always seem to squeak when I come to a stop. I have carbon metallic pads. Is this normal? The brakes are fairly new. — Hal P., Oklahoma

A: Hal, a possible reason your disc-brake pads squeal is because of the carbon metallic brake pads themselves. Carbon metallic pads squeal more than non-carbon metallic pads, so the answer may lie in changing your brake pads to a different brand. However, I personally use carbon metallic disc pads on my car, a ‘94 Trans-Am, and I put up with the minor squealing in exchange for better braking performance.

Now, for all you readers who wonder about brake noise, if your brakes are squealing and you can “feel” something grinding, please take note. You either have time to correct a coming problem, or the problem has already manifested itself. Modern cars have brake wear indicators that will squeal when it is time to change your brake pads. If this is the case, change them now. No harm done.

However, if you’ve driven beyond the warning squeal, you are now into your disc-brake rotor, and the damage is increasing by the day. Get to your garage quick before you completely ruin everything and run out of brakes, too.

Other squeal culprits are warped rotors, sticky brake pistons, misaligned or loose calipers, loose wheel bearings or incorrect pads.

Back to Hal: If you still like carbon metallic pads, ask your mechanic about several “anti-squeal” coatings he can apply. I’m sure you are a car owner who practices preventative maintenance, but for those out there who take their brakes for granted, make sure you check them every time you change your oil.