Note: On models equipped with ABS, refer to Chapter 28 before starting work.
1. The brake pressure regulator is located on the left side of the rear axle, controlled by the up and down movement of the rear axle.
2. To check the action of the regulator, depress the brake pedal sharply and release quickly. The weight of the vehicle is pressing on the suspension and the governor arm should move indicating that the block is not locked.
3. To check for regulator leakage, connect a pressure gauge to the left front caliper and the right rear working brake cylinder or caliper. Since special equipment is usually not available to a home mechanic, have this job done by an Audi dealer. The scheme of the procedure is as follows. Depress the brake pedal so that the pressure in the left front caliper is 100 bar. Fix this pressure for 5 seconds, the pressure in the right rear working brake cylinder or caliper should differ by no more than 10 bar.
4. To adjust the regulator, connect a pressure gauge as described in point 3, the car must be with a net weight, a full fuel tank and a driver. Shake the rear suspension several times, then depress the brake pedal so that the pressure in the left front caliper is 50 bar - the pressure in the rear working brake cylinder or caliper should be 32.5-42.5 bar. With a pressure in the front caliper of 100 bar, the pressure in the rear working brake cylinder or caliper should be 54.0-71.5 bar.
5. If the pressure in the rear working brake cylinder or caliper is too high, loosen the spring attachment to the rear axle and move the unit forward to loosen the tension. If pressure is too low, move set back to increase tension (photo).
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