Car & Truck Brake Pads

Learn All About Brake Pads

A good set of brake pads is essential for safe braking your vehicle. Find out more about brake pads, such as the different types of pads, how brake pad wear gets measured, and DOT brake pad codes.

A brake pad is a steel plate with a layer of friction material designed to drag against the metal brake rotor. It is used in a disc brake system to stop the vehicle.

A brake system's housing, called a brake caliper, straddles a wheel's rotor. It uses two brake pads, one on each side of the rotor. When you step on the brake pedal, a disc brake piston in the caliper squeezes these two brake pads against the rotating rotor. The resulting friction slows the vehicle until it stops.

The brake pad is positioned within the disc brake caliper with the friction side facing the rotor.

Brake pads and rotors are not one-size-fits-all. Brake pads and rotors have different dimensions and features, so only use pads and rotors designed for your specific vehicle.

Brake pads often have a metal tab adjacent to the brake pad. As the brake pads wear down, the tab is exposed and causes loud squeals to alert you that it's time to replace the brake pads. Another cause of sudden squealing is foreign objects caught in the calipers and brake pads. An unevenly worn brake pad also may emit a squeal. If your brakes are squealing, address the issue immediately.

Sometimes, you must remove the wheel and secure the vehicle before measuring the brake pad. New brake pads usually are three-quarters to one-half of an inch in depth. Brake pads should be replaced if they are less than a one-quarter inch. In addition, some brake pads have a hollow wear slot in the middle of the pad. When you can't see the slot, it is time to replace the pads.

Brake pads might wear unevenly due to a part failure or misalignment. For example, if the piston that pushes the pad against the rotor doesn't return to its proper position, it could stick against the rotor and wear faster. Likewise, if wheels are out of alignment, pulling to one side, that will impact the wear of the brake pads.

Yes, many newer cars have an electronic brake-wear sensor. When the sensor detects that a pad is worn down, it will trigger a warning light. If you see that warning light, it's time to replace the pads.

There are three types of brake pads:

• Organic - these were the first replacement for asbestos-lined pads. They tend to work well in most situations.
• Semi-metallic - these help a car stop sooner than organic-lined pads, producing less brake dust. They last longer and tolerate higher temperatures than organic linings. They are best suited for any extended-performance driving.
• Ceramic - these last longer than the other options. They dissipate brake heat faster, and are also cleaner and quieter.

You should expect brake pads to last at least 25,000 miles, depending on your driving habits and the vehicle. Check your owner's manual for the manufacturer's recommendation.

Yes. With the right tools and equipment, brake pads can be replaced in less than an hour. Brake pads slide out easily after the caliper is removed. You will also need to retract the piston. Check your vehicle's repair manual for a description of the steps involved. It's recommended to replace the brake pads on both wheels (front and rear) simultaneously to avoid uneven wear.

Find out more about how to change your brake pads.

If enough of a brake's friction material wears away, the steel backing plate will contact the rotor. That reduces stopping power. The exposed backing plates could also damage the rotors, requiring the brake pads and rotors to be replaced.

Most manufacturers stopped using asbestos in brake pads in the 1990s. Some states, such as California and Washington, banned the sale of asbestos brakes. In addition, the Environmental Protection Agency (EPA) is seeking a nationwide ban on asbestos. Note that asbestos is still used on foreign, aftermarket products.

The US Department of Transportation (DOT) requires that all brake pads are stamped with a two-letter brake code ranging from C to H. The letters represent the friction coefficient or braking power.

• The higher the letter, the higher the coefficient of friction. As you move through the alphabet, the friction increases. Pads with an H have the most friction.
• The first letter indicates the best braking performance at lower temperatures (200 to 400 degrees Fahrenheit).
• The second letter indicates performance at higher temperatures (300 to 650 Fahrenheit). This code is critical for cars used in high-speed driving, such as track racing.
• All the brake pads used on a vehicle should match one another.