Skip the auto shop - Our mechanics make house calls

Why Do Brakes Squeal?

Brake Squeal

If your brakes sound like someone dragging their fingernails across a chalk every time you use them, it's time to have them inspected and repaired. A squealing sound coming from the brakes is not only annoying, it’s downright dangerous, especially if the squealing continues after the car warms up.

In most cases, a squealing sound can be traced back to worn out brake pads or if the car uses a drum brake system, the brake shoes. While deteriorating brake pads are the usual cause of squealing, there can be other causes.

How brakes work

Car brakes come in two different types, disc and drum brakes. A disc brake has a rotor, which is attached to the hub of the wheel, and calipers that hold the brake pads. When the brake pedal is pushed the force is transmitted hydraulically through the brake line, which then forces the brake pads to squeeze the rotor, slowing or bringing the vehicle to a stop. Drum brakes, which are more common on older vehicles, work on the same principle. A drum is attached to the wheel and inside of it are pads or brake shoes, when the brake pedal is pushed the brake shoes push against the drum bringing the car to a stop.

What Causes Brakes to Squeal?

The most common reason disc brakes squeal is because the brake pads are worn out. Disc brake pads have a piece of metal built into them, which is called a wear indicator. As the brake pad material wears away the wear indicator starts making contact with the rotor, which produces a squealing sound. When you hear the sound it's time to have your brake pads checked and most likely replaced.

If the brake pads are not replaced they will eventually wear through completely, and the backing plate will start wearing grooves into the rotor. At this point the squealing noise will be replaced by a grinding noise, and the repair bill will go up substantially.

When the brake pads are replaced the rotors need to be resurfaced. If they are not resurfaced or the job is done incorrectly, there is a good chance the squealing will get even worse.

When it comes to drum brakes the most common cause of squealing is poor contact between the shoes and the drum or brake shoes that have worn out. Regardless of which one is causing the problem the brakes should be inspected and repaired as soon as possible.

Keep in Mind

  • Car brakes will often squeal when they are hot or under pressure. Mountain driving can often lead to squealing brakes.
  • High-performance carbon-metallic brake pads are prone to squealing.
  • All brakes will squeal from time to time. The time for concern is when it becomes a consistent squealing.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
Icon-warranty_badge-02

Skip the repair shop, our top-rated mechanics come to you.

At your home or office

Choose from 600+ repair, maintenance & diagnostic services. Our top-rated mechanics bring all parts & tools to your location.

Fair & transparent pricing

See labor & parts costs upfront, so you can book with confidence.

12-month, 12,000-mile warranty

Our services are backed by a 12-month, 12,000-mile warranty for your peace of mind.

Get A Quote

Need Help With Your Car?

Our certified mobile mechanics make house calls in over 2,000 U.S. cities. Fast, free online quotes for your car repair.

GET A QUOTE

More related articles

Veteran and Military Driver Laws and Benefits in Idaho
The state of Idaho offers a number of benefits and perks for those Americans who have either served in an Armed Forces branch in the...
Veteran and Military Driver Laws and Benefits in New Mexico
The state of New Mexico offers a number of benefits and perks for those Americans who have either served in an Armed Forces branch...
How to Avoid Back Pain in a Car
If you have back problems, sitting in a car for an extended period of time can be excruciating. Even without back problems, you could experience discomfort and soreness from...


Related questions

Q: squeaky brakes.

Squeaky brakes can be frustrating. Let me offer a few suggestions that will hopefully quiet down the noise. The squeal or squeak is due to metal surfaces vibrating without lubrication. Proper lubrication is key to a quiet brake job. The...

Q: Rear brake squealing noise goes off when brakes applied.

Hey there. If the noise was not there before you replaced the brake pads on your 2014 Audi A4, you might want to try replacing the caliper clips and using a good quality brake lube anywhere the pads make contact...

Q: Tools needed to change rear brake cylinder

To replace the brake cylinders, you will need a brake pliers and brake spoon. To bleed the brakes you will need a manual brake bleeder tool. The rest is going to be regular metric hand tools. Make sure to do...