Disc brake service has become routine for most ­import repair shops and, for the most part, offers very few surprises for the service writer and technician alike. Many shops service disc brake calipers by simply replacing them with loaded caliper assemblies, which makes sense in rust-belt areas. In drier climates, calipers can last for many years and may ­require only routine inspection during a disc brake pad replacement.

Nevertheless, in order to appreciate some of the fine points of disc brake repair, it’s important to review the basic elements of caliper service. In the following text, I’ll use a typical caliper service to illustrate some of the issues involved in disc brake service.

CALIPER DIAGNOSIS
Most disc brake services begin with a routine maintenance inspection or with a customer complaint, such as a brake pull or noise. Many caliper failures result in brake-pull complaints because the caliper piston fails to retract. To allow free rotation of the wheel, a very small air gap must exist between the rotor and brake pad. When the pads on one wheel drag against the rotor, the pad may glaze or the brake assembly temperatures may suf...