Being subject to considerable wear and tear, brake pads need to be periodically maintained and replaced. LUMAG, OE manufacturer and aftermarket supplier for CV brake pads and linings, provides CVW readers with a guide to the most likely causes of wear.
Issue: Overlapping friction material – the top edge of the pad overlaps the top of the rotor.
Cause: Wear on the guide pins, caliper or caliper bracket. Also, having the wrong rotor or pad on the vehicle can cause this issue.
Solution: Replace the pads and fit the vehicle with OE specification diameter rotors.
Issue: Outer pad wear – the outer pad continues to ride on the rotor after the caliper releases, resulting in the outboard pad having markedly less friction material than the inboard pad.
Cause: Seizing guide pins, bushings and slides are usually the cause of the issue.
Solution: Correcting this issue is usually fairly straightforward, normally rectified by servicing or replacing the guide pins, bushings, or the entire caliper, and replacing the brake pads.
Issue: Inner pad wear – the inboard brake shows more wear than the outboard pad.
Cause: The caliper piston doesn’t return to the rest position due to a worn seal, damage, or corrosion; it can also be caused by a problem with the master cylinder.
Solution: Take the same steps as fixing the outer pad wear, as well as inspecting the hydraulic brake system and the caliper for residual pressure and guide pin hole, or piston boot damage, respectively. If the pin holes or piston boot are corroded or damaged, then replacement is necessary.
Issue: Even wear – the pads have approximately the same amount of friction material on both.
Cause: Proper brake function.
Solution: Replacement of the brake pads and hardware, such as abutment and anti-rattle clips is required, as well as servicing the caliper guide pins and slides.
Issue: Tapered pad wear – the friction material is worn in a horizontal or vertical wedge pattern.
Cause: Improper pad installation as well as guide pin wear, or having a single guide pin or slide seizing.
Solution: The procedure for rectifying this kind of wear is the same as correcting outer pad wear.
Issue: Cracking, glazing, or lifted edges on the pads – the friction material is physically damaged and shows signs of thermal distress.
Cause: Overuse, improper break-in procedure, hydraulic system problems, seized caliper components, defective pads, and the parking brake not fully retracting are some common causes.
Solution: Replacing and breaking-in the new pads properly. The parking brake may also need adjusting.