The original equipment disc brake pads generally have small sheetmetal wear indicators attached to one of the brake pads. When the brake lining gets too thin, the sheetmetal wear indicator rubs against the brake rotor. The wear indicator does not harm the rotor, but it does makes an irritating screeching noise alerting the vehicle operator that the brake pad replacement is due. This wear indicator is designed to protect the brake rotor from damage from the hard steel backing of the brake pad. In addition, with the brake pads renewed, the vehicle's braking ability stays at its designed level of safety.
Brake pads (also called linings) should be inspected every 6,000 miles (9,600 km), anytime the wheels are removed (tire rotation, etc.), and certainly anytime unusual braking action and/or noise is evidenced. The sheetmetal wear indicators used on many brake pads will give a screeching when the brake pads have worn thin, indicating time for brake pad replacement.
Check both ends of the outer brake pad by looking in at each end of the caliper. These are the points at which the highest rate of wear normally occurs. At the same time, check the lining thickness on the inner pad to make sure that it has not worn prematurely. Some inboard brake pads have a thermal layer against the pad, integrally molded with the lining. This extra layer should not be confused with uneven inboard-outboard lining wear. Look down through the inspection hole in the top of the caliper to view the inner pad. Replace the disc brake pads whenever the thickness of any lining is worn to within 0.030 inch (0.762mm) of the pad. In the case of riveted brake pads, replace when the lining is worn to within 0.030 inch (0.762mm) of any rivet head. Replace all disc brake pads at the same time.
The brake pads must have freedom of movement within the brake caliper bracket. If movement is restricted by rust or debris, the brake pads may remain against the rotor after the brake pedal is released. The can contribute to accelerated brake pad wear, brake pulsation and rotor damage.
- Using a suction gun, remove approximately 2 / 3 of the brake fluid from the master cylinder.
- Raise and safely support the vehicle on safety stands.
- Remove the rear tire and wheel assembly.
- Install a large C-clamp over the brake caliper and against the back of the outboard brake pad. Tighten the C-clamp until the brake caliper piston pushes into the brake caliper bore as far as possible. Remove the C-clamp.
- Check the outer brake pad for freedom of movement relative to the brake caliper bracket. It should move easily.
- Use your hands to push the brake caliper inboard as far as possible. If the brake caliper does not move easily, inspect and replace any worn or damaged brake caliper mounting bolts and/or bolt boots.
- Check the inner brake pad for freedom of movement relative to the brake caliper bracket. If the brake pad movement is restricted, the caliper should be removed for cleaning. Use a wire brush to clean away any rust from the caliper bracket where the pads and retainers contact the bracket. Also clean the ends of the brake pads where they rest on the caliper bracket. Apply a thin coat of silicone grease, GM #18010909 or equivalent, to the brake pad retainers/caliper bracket where the brake pads come in contact with the brake pad retainers and bracket.
- This same inspection operation should be performed on the opposite side.