Squeaky Brakes

Question: I just had my disc brakes replaced and they are now squealing. My mechanic says this is normal.  Why did I have to pay for normal squealing disc brakes? Is he just blowing me off?

Dear concerned car owner,

This unfortunately happens more frequently than we realize. A certain amount of high-pitched brake noise is considered “normal” these days because of the harder semi-metallic disc brake pads that are used on cars now. In my experience, the smaller cars like Honda and Toyota seem to have the most trouble with this. Squeals tend to be heard during the first few stops in the morning when the brakes are cold and somewhat damp from dew, and squeals that are heard during the last few feet while coming to a stop are usually nothing to worry about.

Semi-metallic brakes are made of bits of metal shavings in place of the asbestos material that has been banned by the U.S. government. These semi-metallic brakes have great stopping power and have a long wear life but can cause a high-pitched squeal that drives car owners crazy and frustrates mechanics who can’t get it to go away to please their customers.

Brake squeal is caused by vibration between the brake pads, rotors, and brake calipers. Having the brake rotors refinished or trued (machining a small layer of the metal away from the disc brake rotor to make it smooth and “true” again) and a thin layer of a silicone compound placed on the back of the brake pads are a great way to reduce the squeal if the semi-metallic pads are the culprit of the noise and not due to a worn out disc brake pad.

Why does this squeal happen anyway?

The brake rotor is the round metal object that the brake pads squeeze together like the white part of an Oreo cookie. The rotor is metal and has a smooth slick finish, and the brake pads are made of metal shavings and also have a smooth somewhat slick finish. The more metallic material found in the pad the greater the chance for noise, and vise-versa.

When are squeals signaling a problem?
Sometimes brake squeals are an indication that maintenance is required. Some common conditions that cause brake noise are:
Heat cracked or worn “un-true” rotors

Rough finish on resurfaced rotors

Loose fitting brake pads in the brake calipers

Lack of silicone compound on back of brake pad

Missing springs or anti-rattle clips that should be on the caliper or pad

Improper tightening sequence of lug nuts or caliper hardware

Contamination on the brake pad such as brake fluid

If you hear brake noises other than a squeal, it could mean your brake pads are worn out and need to be replaced. If your brake pedal feels different than normal or if you’ve noticed any change in the way your vehicle brakes (pulls to one side when braking or requires more pressure on the brake pedal), or loss of brake fluid have the brake system inspected at once.

What should I do?
What can you do as a customer to reduce the chance of squealing brakes? First of all, noisy brakes should always be inspected to make sure there isn’t a problem with the braking system. If the pads have worn down to the point where metal-to-metal contact is occurring, your vehicle may not be able to stop safely, and you may damage the brake rotors or drums to the point where they have to be replaced. Sometimes a few harder-than-normal stops can “de-glaze” the brake pads and help reduce the squealing noise for a while.