Brake Force Regulator

The brake force regulator (1) for the rear axle of front-wheel-drive models is connected to the rear axle by a spring (2) and a drive lever (3).

The 5-cylinder engine is equipped with an additional vacuum pump (2), which further increases the reduced pressure in the hose from the intake manifold (1). Thus, sufficient force is provided in the hose (4) in front of the pump to the booster (5) to apply the brakes. To prevent loss of vacuum, a check valve (3) is installed before the branch to the pump.

Here the vacuum pump is shown again at close range. The numbers correspond to the left illustration.

On front-wheel-drive versions of the Audi 80, the brake force regulator is located at the right side of the left bearing bracket, in front of the rear axle when viewed in the direction of travel. It can reduce the fluid pressure in the rear wheel cylinders.

This depends on the load: with the vehicle fully loaded, the rear body lowers; with a light load, when one or two persons are in the vehicle, the deflection of the rear springs is small. Due to excessive pressure on the rear wheels, they lock prematurely, and the vehicle may swerve sideways during braking.

The brake force regulator receives information about the vehicle load through a spring connected to the rear axle, depending on how far the rear axle has lowered.