Why Do Brakes Squeal? Question Of The Day


Not all sounds coming off of your brakes mean the same thing.

Photo by Ian Cameron / Flickr

Question: What makes brakes squeak? Why do some brakes give off so much dust on hubcaps and others do not?

Answer: The brakes on your car allow you to defy Newton’s First Law of Motion at every red light. A body in motion will remain in motion unless it has a good set of brakes.. They have also been squeaking since they were invented.

The component parts of a car’s braking system – things like the rotors, the brake pads, and the wheels—can vibrate and that vibration makes noise. The brake pads are designed to disintegrate slowly under pressure. If the noise becomes more squeal than an occasional squeak, it could be the warning system built into the brakes to let you know that the pads are nearing the end of their life cycle. There are small steel clips designed to make that noise to let you know it is time for maintenance. (Not sure if the noise your brakes are making is the helpful squeal or a more menacing grinding noise? Pep Boys has sample sounds on their website. The squeal is a higher pitch sound sort of like whistle. The grinding is lower in pitch and more like nails on a chalkboard.)


Photo by Emil / Flickr

Just like squeaking, brake dust is a fact of life. Brake dust is not evidence of a problem with the brakes. Heat and friction break down the pads, which creates the dust. The problem is more of a cosmetic one: all of that dust makes the rims look dirty.

Brake dust is such a perceived problem that JD Power includes it as a factor in the “Initial Quality Surveys” that the company conducts. Excessive brake dust falls in the design category under overall driving experience. The dust isn’t a new problem, but the trend towards open-wheel design helps contribute to the concern about dust on the wheels. Before, hubcaps hid the dust.

The metal fibers in the dust can be corrosive, and build-up could permanently etch the wheel. Replacing the pads with ceramic brakes could help solve that problem. As Pat Goss, Motorweek’s master technician said, ceramic brakes still create dust, it is just lighter in color and easier to clean because it doesn’t have the corrosive metal fragments.

Check out your local auto parts store for products that can help remove brake dust and keep your wheels looking good. Whichever product you decide on, make sure you let the wheels cool before you start cleaning.

We’re scouring the Internet to uncover interesting questions that people have posted looking for advice from the unwashed masses. We will contact experts to give you well-researched, professional advice. You can also submit questions to autos_qotd@yahoo.com.