Brake Noise

SCRAPING OR GRINDING, DISC BRAKES

Causes
- Front pads/linings worn down to the rivets or metal backing-plate.
- Excessive grooves in rotors.
- Rust or dirt accumulation on the rotor or caliper assembly.
- Damaged or bent pads/linings.

What to Check For
- Inspect linings and replace if;
- Excessively worn or grooved.
- Cracked.
- Bent or warped.
- Inspect the rotor for excessive grooves, resurface or replace as necessary.
- Verify the rotor splash guard is in place and that no debris is dodged in the caliper/rotor area.

SQUEAL, DISC BRAKES

Causes
- Pads/linings are worn to minimum thickness, wear indicators are contacting rotors.
- Pads/linings are glazed.
- Pads are loose in the caliper housing.

What to Check For
- Inspect linings for;
- Minimum thickness, replace if necessary.
- Glazed appearance, replace if necessary.

NOTE: Brake linings become glazed as a result of overheating or brake drag. If the linings are glazed, first determine the cause before replacing them.

- Loose fit in the caliper. Crimp outer pad ears onto caliper housing, or replace missing or damaged anti-vibration clips. (As applicable.)

Anti-squeal Coating:

NOTE: Anti-squeal coating or pad insulator shims are very effective in preventing brake squeal on new brakes.

CLICKING OR RATTLE, DISC BRAKES

Causes
- Pads/linings loose in the caliper housing.
- Loose wheel bearings or grease cap.
- Loose lug nuts.
- Loose caliper mounting bolts.
- Caliper sticking or binding on the slides.

What to Check For
- Verify that the pads fit snugly in the caliper. If pads are loose, crimp outer pad ears onto caliper housing, or replace missing or damaged anti-vibration clips. (As applicable.)
- Adjust the wheel bearings and check that the axle nut cotter pin is not contacting the dust cap
- Loosen lug nuts and re-torque to the correct specification.
- Inspect and torque mounting bolts. Replace any missing or damaged hardware.
- Clean and lubricate the caliper slides.

Disc Brake Mechanical Force Diagram:

NOTE: Floating calipers require free and unrestricted movement on the caliper mounting. Floating or sliding calipers have pistons only on one side of the rotor. The first part of the piston's travel forces the inner pad against the rotor, then further travel forces the movable part of the caliper to pull the outer pad against the rotor.