Several factors can lead to brake failure:
- Grease or oil on brakes causes brake failure, because it interferes with friction. If oil leaks, it may indicate that an oil seal has failed.
- When the brakes overheat to a great degree, the metal in the brake rotors or drums develops hard spots. These are known as hot spots. The hot spots resist the friction from the brake shoes and pads. Because the shoes or pads have nothing they can grasp, there's no friction. Consequently, braking power is lost.
- Brakes that squeal indicate that the brake pads are wearing thin. By the time the brakes begin making a grinding sound, they've worn down past the pads to the rotors, which will cost more than pads to replace [source: Gray].
Do you know anyone who nervously "rides the brake" when driving? How about the scaredy-cat driver who often stops in a panicked way? This type of driver is headed for crystallized brake pads or shoes. Because of the heat generated over repeated overuse of the brake, the pads and the shoes grow hard and are ineffective. Brake material has to be flexible and able to grasp the disc or drum in order to stop the vehicle.
Recommendations for Servicing Brakes
Inspect brake pads and shoes annually and replace them if they are worn. Change the brake fluid every 48,000 miles, every four years, or during regular brake servicing.