Brake pads are one of the few remaining accepted wear items in a modern vehicle. As a result, it represents a significant revenue opportunity for the service community.

Drivers would surely love to have brake pads last for life. Service shop owners may have a different opinion. I'm sure that shop owners must deal daily with the question from the customer regarding the life of the pads. How many miles should I get out of a set of pads? Why did they wear out so quickly? My buddy got at least 10,000 more miles on his brakes than I did?

What determines pad life and how can it be influenced? At its root, the amount of pad wear is established by the particular wear characteristics of the friction material (and rotor), the number of stops and how aggressively the vehicle is braked.

The pad wear rate is established by some standard tests. These tests are conducted on a brake dynamometer. The pad is first run through a burnish and then the brake is subjected to a series of stops at a range of temperatures. The test will run stops at 100ºC, 200ºC, 300ºC and 400ºC and then repeated at 100ºC. The wear rate at each temperature is established. Generally, the wear at the higher temperatures is significantly more than at lower temperatures.

Wear rate at 400ºC can easily be four or more times the lower temperatures. The chemistry of the pad determines the wear characteristic. Semi-metallic materials usually have lower wear rates...