A family of disc brake systems, capable of braking vehicles with gvw's from 3000-6000 lb, has been developed and released on the 1965 Lincoln and Thunderbird with power brakes as standard equipment, and on the 1965 Mustang with manual brake as an option. These systems, while retaining the desirable characteristics of current drum brake systems, provide significant performance advantages in the areas of fade resistance, stability, and serviceability. The disc brake systems on the Ford products consist of a ventilated rotor, in conjunction with a fixed, multiple-piston caliper utilizing segmental brake linings. Duo-servo rear brakes are used with a hydraulic proportioning valve which compensates for the nonlinear rear brake output.