Pads have about equal amounts of friction material on both pads.
This is caused by proper brake function. To fix this kind of wear, replace the brake pads and hardware such as abutment and anti-rattle clips, service the caliper guide pins and slides.
Outer Pad Wear
The outboard pad has significantly less friction material than the inboard pad.
Wear like this is caused by the outer pad continuing to ride on the rotor after the caliper releases. Seizing guide pins, bushings and slides are usually at the heart of the problem. Correcting this kind of wear is relatively simple. Service or replace the guide pins, bushings, or the entire caliper, and replace the brake pads.
Inner Pad Wear
The inboard brake shows more wear than the outboard pad.
This happens when the caliper piston is not returning to the rest position due to a worn seal, damage, or corrosion. It can also be caused by a problem with the master cylinder. To correct this kind of wear, take the same steps as fixing 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, they should be replaced.
Tapered Pad Wear
The friction material is worn in a horizontal or vertical wedge pattern.
This kind of wear is caused by improper pad installation as well as guide pin wear. Having a single guide pin or slide seizing can also cause tapered wear. The procedure for correcting this kind of wear is the same as correcting outer pad wear.
Cracking, Glazing, or Lifted Edges on the Pads
The friction material is physically damaged and shows signs of thermal distress.
This can be caused by many things. Overuse, improper break-in procedure, hydraulic system problems, seized caliper components, defective pads, and the parking brake not fully retracting are some common problems. This can be corrected by replacing and breaking-in the new pads properly. The parking brake may also need adjusting.
Overlapping Friction Material
The top edge of the pad overlaps the top of the rotor.
This can be caused by wear on the guide pins, caliper or caliper bracket or having the wrong rotor or pad on the vehicle. To correct this kind of wear, replace the pads and fit the vehicle with OE specification diameter rotors.
Tips and Guidelines
• Some electronic brake distribution may have faster than normal rear brake pad wear rates. This is normal in some cases. The reason for this wear is because the rear brakes are used to control nose dive. If the wear is greater than expected, check for TSBs. Often, the OEM will issue new software for the hydraulic control module that solves the problem.