See Figure 1
Front Disc Brakes were available as an option on full-size models since the mid 1960s. From 1968 to 1972, floating caliper front disc brakes were available on all models. Starting in 1973, sliding caliper front discs were made standard equipment with vacuum power assist.
Beginning in 1976 models, a 4-wheel disc brake system utilizing sliding caliper Rear Disc Brakes was made available on station wagons and police interceptor packages. When equipped with the 4-wheel disc brake system, brake assist is provided by a hydraulically operated servo system known as Hydro-Boost, in lieu of the traditional vacuum assisted type. In 1979, the four wheel disc brake option was discontinued.
The rear sliding caliper assembly is similar to the one used on the front, except for the parking brake mechanism and a bigger anti-rattle spring. The parking brake lever on the caliper is cable operated by depressing (or releasing), the parking brake pedal under the dash panel.
When the pedal is depressed, the cable rotates the parking brake lever (on the back of the caliper) and the operating shaft (inside the caliper). Three steel balls, which are located in pockets on the opposing heads of the shaft and thrust screw, roll between ramps formed in the pockets. The motion of the balls forces the thrust screw away from the shaft which, in turn, forces the piston and pad assembly against the disc to create braking action.
An automatic adjuster in the piston compensates for pad wear by moving the thrust screw.