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
   Drive of management of coupling
   Coupling service life
   Coupling check
   Check of the hydraulic drive of coupling
   Coupling removal
   List of malfunctions
+ Transmission and transmission
+ Suspension bracket and steering
+ Brake system
+ Anti-blocking system of brakes
+ Wheels and tires
+ Body electrical system
+ System of ignition
+ Lighting
+ Signalling devices
+ Devices and auxiliary devices
+ Heating and ventilation
+ body Elements
+ Search of malfunctions
+ Specifications

Check of the hydraulic drive of coupling


  1. If coupling is divided correctly, the hydraulic drive of coupling anyway too as it should be.
  2. If coupling is divided badly or the pedal fails without resistance, it is clear that air got to the hydraulic drive. Simple removal of air in this case will not help – it is necessary to find and repair not tight place. After that it is possible to be engaged in removal of air. Other reasons for which coupling is not divided correctly, are specified in the list of malfunctions at the end of the head.
  3. Who wants to carry out just in case an inspection of the hydraulic drive of coupling, has to look for smudges of brake fluid on the main cylinder (above at a coupling pedal) and in the working cylinder (near a transmission).
  4. Cylinders of coupling, damp from oil, are not tight and have to be replaced. But without thorough cleaning of area round the working cylinder the origin of an oil spot on it can be defined with great difficulty.

 Help: liquid though comes to hydraulic system of coupling also from a tank with brake fluid, however at a leakage in the hydraulic drive of coupling danger does not threaten brake system. The intaking branch pipe of the hydraulic drive of coupling is located in a tank rather highly so always there is enough liquid for work of brakes.

Removal of the main cylinder of coupling


  1. To select perhaps bigger amount of liquid from a tank with brake fluid (for example, an old syringe).
  2. To turn off a shelf at the left under the dashboard (see Salon)
  3. To enclose an old rag under the main cylinder, to remove the bringing hose and to allow the remains of liquid to flow down in a rag.
  4. In a motor compartment to the left of the amplifier of brakes to turn off the pressure head hydroline to the working cylinder.
  5. To turn off two bolts (with an internal hexagon) fastenings of the main cylinder.
  6. To hook a lock washer of a hinged finger (connection a pedal / the main cylinder), to squeeze out a finger.
  7. Now it is possible to remove the cylinder.
  8. At installation of the new cylinder it is necessary to adjust a rod which presses on the piston of the main cylinder so that the pedal of coupling settled down approximately on 10 mm over a brake pedal.
  9. It is obligatory to pay attention: the returnable spring has to return a pedal correctly. Thus the pedal in a starting position (rest) should not rest against an arm of the pedal block.
  10. For adjustment to weaken a lock-nut on the pushing bar and to turn a bar to the left or to the right round its own axis. Then again to tighten a lock-nut.
  11. To clean air from the hydraulic drive of coupling (to pump over).

 Help: the coupling pedal in Audi 80 is supplied with the spring located above a dead point. It helps when pressing a pedal, however after an otpuskaniye of a pedal squeezes out it again in a starting position. If the pedal does not come back, it means that air or bearings of a pedal or a spring got to a hydraulic actuator jam.

Removal of the working cylinder of coupling


  1. To raise and fix the left forward side of the car.
  2. To turn off a pressure head hose of the hydraulic drive of the working cylinder – it is careful, brake fluid which needs to be collected follows.
  3. To weaken a fixing bolt on the cylinder, to extend the working cylinder from a transmission case in the direction back.
  4. If necessary to use an aerosol for removal of a rust and mount.
  5. Slightly to grease the new cylinder on unpainted walls of the case, to apply MoS2 paste on a driving pusher.
  6. To insert the working cylinder into a case of a transmission and to press so that it was possible to screw in a fixing bolt in a carving on the transmission case (25 N • м).
  7. To pump over the hydraulic drive of coupling.

Pumping of the hydraulic drive of coupling

If you on hand do not have a device used usually to this purpose in a workshop, can pump over coupling by the same method, as brake system (the head "Brake system") or, almost without loss, the next way:


  1. To open the valve of pumping of one of forward wheels and the valve of the working cylinder of a hydraulic actuator of coupling everyone approximately on one and a half turns.
  2. To connect both valves a hose.
  3. Now several times slowly and carefully to press a brake pedal in order that brake fluid from a forward brake was pressed through in the hydraulic drive of coupling.
  4. Not to press with a force, differently the hose can come off!
  5. To watch the level of brake fluid in a tank.
  6. If air bubbles from a coupling hydraulic actuator do not rise from a tank with brake fluid any more, so it is possible to close both valves and to remove a hose.
  7. To check the level of brake fluid!