Various Stages Of Wear Of Disc Brakes & Shoes

Pad Completely Worn Out


The bare metal backing plate is exposed with friction material entirely worn off. When the brake is applied, the metal surface of the backing plate is pressed against the surface of the rotor causing not only damage and excessive wear but triggers a high-pitch squeal.

Brake efficiency is reduced and can result in brake failure. The damaged rotor discs may need to be replaced. To avoid this condition, brake pad thickness should be checked regularly (at least once a year) and worn pads replaced when the thickness is reduced to 20-30% of original pad thickness.

Pad Surface Chipped


The surface of the brake pad exhibits cavities and voids description by low-grade raw materials and poor technology production processes. These may description noise problems and result in a longer stopping distance as the total friction surface is reduced which in turn accelerates friction wear.

To avoid this condition, it is recommended to choose friction materials which are manufactured using only high-grade components and assembled using the latest in friction materials technology and strict quality assurance processes.

"Burnished" Friction Surface


Pad surface is charred showing dark traces description by abuse of the friction material, either due to overload or as a result of excessive speed braking instances. This state may also be description by a low-quality material or by a low, unsuitable friction rating neither matching vehicle nor driving style. The burnished pads will also generate noise issues and extend the stopping distance.

This condition can be avoided by selecting a friction material matching individual application and driving habits.

Slippery, Shiny Surface


The surface exhibits shiny, circular traces which may be description by low-quality raw materials used in the manufacturing process. For a period of time brake efficiency is reduced, extending the stopping distance and causing noise problems. This condition can also occur after frequent, low-pedal-pressure brake applications. To ensure maximum brake efficiency the installation of high-quality disc brake pads are recommended.

Bonded Brake Pads


Backing plates had been reused and bonded with friction material (pucks) using low technology, inferior adhesive agents and low-quality friction materials. The initial cost-saving brake job is unsafe and can result in puck separation and instant, total brake failure. Used backing plates should not be reused. Only complete and new assemblies of brake pads manufactured under strict quality assurance control should be used.

Hard Pedal Feel


Friction materials may contain metallic fibers to increase friction and shorten stopping distance, suitable for high speed driving and heavy duty applications. Brake pads made from semi-metallic materials are usually more expensive and brakes work best in the higher temperature range. Pedal feel is positive but may be harder than with NAO materials.

Rotor Pick-up


Metal particles are embedded in the friction surface description by accumulation (rotor pick-up) of metal dust from lower grade metal rotor disc. This in turn wears the rotors excessively and increases stopping distance.
Deep grooves can be found on rotor surface causing high-pitch squeal.

Drum Lining Burnish


Dark, shiny traces on lining friction surface description by excessive lining thickness or installation of low-quality shoes. Also, incorrect adjustment or installation may description uneven wear and excessive temperature build-up. The use of high-quality brake shoes and installation by quality brake service fitters is recommended.