Audi 80/Avant (B4)

since 1991-1995 release

Repair and operation of the car



Audi 80/Avant
+ Technical specification
+ Engines
+ System of production of the fulfilled gases
+ Cooling system
+ Fuel tank and fuel pump
+ Air filter and airintaking channels
+ System of injection
+ Coupling
+ Transmission and transmission
+ Suspension bracket and steering
- Brake system
   Check of brake mechanisms
   Brake fluid
   Check of level of brake fluid
   Check of tightness of the brake system
   Replacement of brake fluid
   Disk brake mechanisms
   Measurement of thickness of blocks of the disk mechanism
   Control of a condition of brake disks
   Replacement of blocks of disk brake mechanisms
   Drum brake mechanism
   Measurement of brake shoes of the drum mechanism
   Check of the course of a pedal of a brake
   Disk brake mechanism of back wheels
   Measurement of thickness of blocks of back disk brakes
   Check of a free wheeling of the lever of the parking brake
   Main brake cylinder
   Amplifier of brakes
   Check of the amplifier of brakes
   Regulator of brake forces
   Repair of the hydraulic drive of brakes
   Pumping of the brake system
   List of malfunctions
+ Anti-blocking system of brakes
+ Wheels and tires
+ Body electrical system
+ System of ignition
+ Lighting
+ Signaling devices
+ Devices and auxiliary devices
+ Heating and ventilation
+ Body elements
+ Search of malfunctions
+ Specifications





Amplifier of brakes

Disk brake mechanisms do not operate in a self-amplifying way as, for example, drum. Much higher brake force is necessary. Therefore Audi 80 is supplied by the pneumatic amplifier of the brake drive adding about 60% of brake force. Despite it, the pedal of a brake is directly connected with the brake piston in the main brake cylinder so it is possible to brake also at the failed amplifier. But the necessary pressure upon a pedal in this case needs to be increased several times.

Additional force is provided by the lowered pressure from an inlet collector. The amplifier of brakes is connected by a hose with a final collector. When braking the difference in pressure between the external pressure of air and the lowered pressure in a final collector shifts a big elastic diaphragm and in addition presses on the piston in the main brake cylinder. If the engine is not started, then the amplifier cannot develop any (additional) brake force. If the engine suddenly becomes deaf, then still there is a small reserve for a quantity of braking; but then it is necessary to hope only for force of legs.

Vacuum pump

For improvement of support of brake force the 5-cylinder engine is equipped with the additional vacuum pump installed at the left at a head of the block of cylinders and set in motion by the camshaft. Thanks to it the lowered pressure in hoses to the amplifier of brakes increases.








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