General description (Audi 100 C3)

The braking system has a hydraulic booster, a dual-diagonal hydraulic circuit with disc brakes on the front and drum or disc brakes on the rear wheels, depending on the model. Each circuit of the system controls one front and one diagonally opposite rear brake from a dual master cylinder. In normal operation, both circuits work evenly; however: if one circuit breaks, the braking force will still act on both wheels. The brake pressure regulator is included in the rear brake hydraulic line. This unit regulates the pressure applied to each rear brake and eliminates the possibility of the rear wheels jamming during sudden braking.

Front disc brakes are controlled by a single piston that actuates calipers. On models equipped with rear drum brakes, the brake shoes are controlled by dual-piston wheel cylinders and a self-adjusting brake pedal system. On models equipped with rear disc brakes, a single piston actuates calipers similar to those used on the front brakes. On all models, the handbrake is cable-operated and provides an independent mechanical means of actuating the rear brake.

The brake booster is of the conventional vacuum type on direct-acting steering models or hydraulically operated on power-assisted steering models. System pressure for the hydraulic booster is generated by the power steering pump and is stored in a pressure accumulator. The pressure accumulator is used by the hydraulic booster unit when the brake pedal is depressed. Anti-lock braking system (ABS) is also installed as standard or optional, depending on the model. More detailed information on this system can be found in the relevant Chapters of this Section.

Warning: On models equipped with anti-lock brake systems (ABS), when working on the brake system, take some additional precautions, as Chapter 28 before performing any action described in this Section.