Passenger cars that use four wheel disc brakes with rear calliper park brake systems usually rely upon parking brake application to maintain the correct clearance between the rear disc‐brake pads and the rear rotors. Because customers with vehicles fitted with automatic transmissions frequently are not in the habit of applying the parking brake every time they stop the car, the clearance between the pads and the rotors becomes excessive after a period of time. When this happens, the rear brakes do not do the portion of the braking that they are designed to do and premature front pad wear occurs.
This premature front‐pad wear is particularly evident after the front brakes alone are relined. This pad wear will occur regardless of whether the rotors and callipers are rebuilt or replaced. The solution to the problem is to educate your customers to use the parking brake on a regular basis. Modern parking brake cables are protected from corrosion and binding and generally do not freeze up as the parking brake cables of years ago did. If the customer has not been in the habit of using the parking brake, it may take as many as 40 to 50 applications of the parking brake to obtain the proper clearance between the disc‐brake pads and the rear rotors.
Also, it is a good idea to maintain some lubrication between the parking brake cables and the outer case even though the cables may be encased with a protective coating. It has become acceptable to use synthetic or silicone grease in the area where the parking brake enters its shield casing. Synthetic or silicone grease does not attract dirt or moisture and will maintain a free parking brake situation throughout the life of the car if done on a periodic basis.
Disc Brakes Australia