Above the main brake cylinder in the engine compartment under the cover is a compensation tank, which supplies brake fluid to both the brake system and the hydraulic clutch drive. The brake booster is driven by an air vacuum formed in the intake manifold of gasoline engines. Due to the presence of a corresponding valve, the braking force created by the brake pedal is increased if necessary by means of a vacuum. Since the vacuum in the intake manifold of diesel engines is insignificant or absent, a vacuum pump is installed on them for the brake booster. The vacuum pump is flanged to the cylinder block and is driven via the camshaft.
Brake pads are covered by the operating permit - ABE (Allgemeinen Betriebser-laubnis), in addition, they are intended by the factory for the corresponding car model. Therefore, it is recommended to use only brake pads approved for use by the car manufacturer or the Federal Motor Vehicle Authority - KVA (Kraftfahrtbundesamt). Such brake linings have a corresponding KBA approval number for operation.
Note: On roads that are very wet from rain, it is necessary to brake from time to time while driving in order to free the brake discs from deposits. Due to centrifugal forces, water is thrown off the brake discs, but a thin silicone film, rubber wear products, grease and other contaminants remain, which reduce the effectiveness of the brakes.
Burnt dirt and rain cavities on the brake pads will cause scratches on the brake discs. This can result in reduced braking performance.
Safety instructions
Cleaning the brakes creates brake dust, which can cause health hazards. Therefore, when cleaning the brake system, care must be taken to avoid inhaling this dust.
ABS/HBA/EBV/EDS systems
Work on electronically controlled brake and chassis components must only be performed by trained personnel.
ABS (Anti-Blockir-System) — the anti-lock braking system prevents the wheels from locking during sudden braking. Thanks to this, the car remains controllable during braking.
[The original article is available at: VWmanual]
NVA (hydraulischer Bremsasistent) — the hydraulic emergency braking system recognizes an emergency situation based on how quickly the brake pedal is pressed. In a matter of seconds, the emergency braking system automatically creates additional braking pressure over and above the pressure created by the driver through the brake pedal. Thanks to this, maximum braking of the car is created at the limit of wheel locking and the braking distance of the car becomes shorter, even if the driver does not press the brake pedal vigorously enough.
EBV (elektronische Bremskraft-verteilung)— the electronic brake force distribution system reduces the braking forces for the rear wheels using the ABS hydraulics. Since the electronic EBV control is more sensitive than the mechanically acting brake force regulator, the regulation range becomes significantly wider. Cars with ABS type 60 are equipped with the EBV system.
When driving in a straight line, the rear brakes absorb the full braking load. In order to ensure the vehicle's stability when braking on a bend, the braking effect of the rear axle must be reduced. The ABS speed sensors enable the EBV to determine whether the vehicle is driving straight or on a curve. When driving on a curve, the braking pressure for the rear axle is reduced. This allows the rear wheels to absorb the maximum lateral force.
EDS (elektronische Differentialsperre) — the electronic differential lock system brakes the slipping wheels when starting off. Thanks to this, the torque is transmitted to the wheel with higher traction.
The electronic differential lock operates when starting off and automatically switches off when the vehicle speed exceeds 40 km/h. The particular advantage of this method of improving traction is that it does not negatively affect either the vehicle's dynamic qualities or the comfort of control during acceleration.
Operating instructions for ABS/EBV/EDS systems
The battery switch in the electronic control unit ensures automatic shutdown of the system if a fault occurs (for example, a broken wire) or too low operating voltage (battery voltage below 10 volts). This is accompanied by the indicator on the instrument panel lighting up. At the same time, the regular braking system continues to function and the car behaves when braking as if the ABS system was not installed on it.
Safety instructions
If the ABS and brake system indicators are on while driving, then during sudden braking the rear wheels will lock, since the necessary distribution of braking forces in this case is not present.
If during a trip one or more warning lights come on on the instrument panel, you must do the following:
- Stop the car, turn off the engine and start it again.
- Check the battery voltage. If the voltage is less than 10.5 volts, charge the battery.
Note: If the warning lights come on at the start of a trip and go out after a while, this indicates that the battery voltage was initially insufficient and then increased as a result of charging from the generator.
- Check whether the battery terminals are tight enough and have good contact.
- Raise the car on jacks, remove the wheels, check the electrical wires of the speed sensors of all four wheels for external damage (grinding). Other checks of the ABS/EBV/EDS systems must be entrusted to a service station.
Caution: Before carrying out welding work using an electric welding machine, the plug connector of the ABS control unit in the engine compartment must be disconnected. The plug connector must only be disconnected with the ignition switched off. During painting work, the control unit may be briefly exposed to a maximum temperature of +95°C and for a long time (no more than two hours) — exposure to temperature +85°C.
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