Brake Noise

You're cruising toward a column of cars waiting at a stoplight. You apply your brakes and are then rewarded with a sound that, like fingernails on a chalkboard, raises goose bumps on your neck—and maybe the blood pressure of the driver in front of you. Sound familiar?

An annoying noise can be one of the first signs that's something's wrong.
Like everything else automotive, an annoying noise can be one of the first signs that's something's wrong, or it might mean nothing at all is amiss. It's up to you to quickly figure out which. Keep in mind that, in most cases, a persistent noise, even after the brakes have warmed up, indicates that a repair is in order. To help determine whether squealing brakes are simply a nuisance or an ominous sign, here's a quick run-through of the disc brake action that starts with the foot on the brake pedal and ends with a stopped vehicle.

Brake Action
The pedal pressurizes a hydraulic system that pushes the brake caliper pistons out of the calipers, contacting the brake pads and pressing them against the spinning brake rotors. The contact of the pad's friction material on the rotors converts kinetic energy into heat and slows the vehicle. The obvious first step in the squeal search is to eliminate serious system problems. Brakes do not simply fail—they deteriorate. One element of the system wears and, over time, takes the rest of the system with it.

System Wear Brakes do not simply fail—they deteriorate.
The most common example is a badly worn brake pad, a simple and inexpensive fix. The next component in line for wear is the brake rotor that the pad rides against when the brakes are applied. A brake pad, worn down to its backing plate, will eat grooves in the rotor. Not an inexpensive fix.


To avoid the domino effect of worn brake parts, check for excessive pad or shoe wear. Look for oil or grease on pads or shoes, warped or scored rotors or drums, misaligned/loose calipers, and sloppy wheel bearings. Also be on the watch for glazed pads or rotors or sticky pistons. If there are rust or corrosion deposits on brake elements, this could be the sign that the piston is sticking. If pads or shoes are worn unevenly, side to side, a sticking piston could also be to blame.