The brake fluid expansion tank is located in the engine compartment on the left under the fine air filter and supplies the entire brake system with fluid.
The brake booster is driven by an air vacuum, which in petrol engines is created in the intake system. Thanks 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 system of diesel engines is insignificant, the vacuum for the brake booster is created by a vacuum pump flanged to the cylinder head.
All disc brakes are equipped with a caliper with a so-called floating bracket. This means that in each caliper, when braking, the brake pads are pressed against the brake disc by only one piston.
The brake calipers are made of light alloy. Due to this, the brake mechanisms are particularly light and provide good heat dissipation, thereby preventing the so-called fading, i.e. a decrease in their efficiency.
There is a sensor installed at the front left and rear right that transmits signals to the brake pad wear indicator.
Parking brake mechanism (handbrake) has a cable drive and acts on the rear wheels. Since the disc brake mechanism is not quite suitable as a parking brake, there are 2 additional shoe brakes on the rear wheels, which are combined with the brake discs. These shoe brakes are activated only by the hand lever of the parking brake mechanism.
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.
Brake linings are subject to the operating permit – ABE (Allgemeinen Betriebserlaubnis), in addition, they are intended by the factory for the corresponding car model. Therefore, it is recommended to use only brake pads from BMW or those approved for use by the Federal Motor Transport Agency - KVA (Kraftfahrtbunde-samt). Such brake linings have a corresponding KBA approval number for operation.
Work with the brake system requires extreme cleanliness and sophisticated work techniques. If the necessary work experience is not available, then work with the brakes should be carried out in a specialized workshop. Used old brake fluid should be handed over to a special waste collection point, do not spill it or throw it away with household waste. City and district administrations should inform about the location of the nearest collection point.
Note: On roads that are very wet from rain, it is necessary to brake from time to time during the trip 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.