Rear drum brakes (Audi 100 C4)

Audi models with low-power engines are equipped with drum brakes on the rear wheels. On this version of the brakes, two brake shoes are pressed by pistons of the brake wheel cylinders (they are located between the upper ends of the brake pads) are pressed against the brake surface of the drum. Due to the arrangement of the brake shoes of the drum brake used on these Audi models (single brake - one brake cylinder with two pistons), one of the shoes reinforces the other. This means that the shoe, due to the rotation of the wheel within certain limits, is independently pulled towards the brake drum, which reduces the force on the pedal. On Audi models, it is (when moving forward) the front brake shoe, which is called the active or primary shoe. The rear shoe is called the passive or secondary shoe.

Self-adjusting drum brakes

Drum brakes do not require adjustment. Of course, it works differently here than with disc brakes - mechanical adjustment. The pressure rod between the brake shoes must be extended in accordance with the wear of the linings, so that the linings fit against the drum. This is achieved by a key under the action of a spring, which gradually presses the wearing shoes against the rod.