12. Brake system
All E28 models (with "retro" - a body) are equipped with disk forward brakes, and either drum-type, or disk back brakes. (With a modern body) lobbies and back disk brakes have the E34 models. Both forward, and back brakes on all models the self-regulating. Some latest models are equipped with anti-blocking brake system (ABS); it is described in the Section the General information on anti-blocking brake system.
The hydraulic system consists of two separate contours. The main cylinder has separate tanks for each of two contours, and in case of leakage of liquid or refusal of one of contours another will continue to work.
The vacuum amplifier using vacuum and atmospheric pressure of the inlet pipeline of the engine for ensuring of strengthening of hydraulic system of brakes, is established on a partition of an impellent compartment.
On the E28 models the hydraulic amplifier is established. This system uses hydraulic pressure of the steering pump for strengthening of brake system.
The parking brake is connected with back brakes and is put in action by a cable by means of the lever located on the central console. Assembly of the parking brake on models with back drum-type brakes is a self-regulating part of assembly of the back drum-type brake mechanism. With back disk brakes the parking brake works at models by means of pair of the brake boots located in the central part of a back brake disk, and is regulated manually.
Alarm system of wear of brake shoes
The alarm system of wear of brake shoes is connected with a red alarm lamp on an instrument guard which is lit when brake shoes wear out to a condition demanding their replacement. DO NOT IGNORE this signal. If you do not replace a block shortly after this lamp lit up, brake disks will be damaged.
On some models the alarm system of wear of brake shoes also includes a lamp of a warning signal which lights up only when the brake pedal is squeezed out to warn you in advance that it is necessary to replace blocks.
The sensor of wear fastens to brake shoes. It is located on the left forward wheel; on some models there is a sensor and on the right back wheel. The sensor of wear is a part of the closed chain. As soon as blocks wear out to level of contact with the sensor, the disk starts to erase that part of the sensor that is turned to a disk. The wire in the sensor thus frays and the red lamp on an instrument guard is lit.
Always check the sensor (and) at replacement of blocks. If you replace blocks before the alarm lamp, the sensor lights up (and) can remain serviceable; if the signal already lit up, it is necessary to replace the sensor.
After completion of any procedure demanding dismantling of any part of brake system, always do trial departure to check work of brakes before normal operation of the car. Check of brakes make on a pure, dry and equal surface. Otherwise results of testing will be inexact.
Check brakes on different speeds, by easy and strong pressing a brake pedal. The car should stop evenly, without turning in one party. Avoid blocking of brakes since it leads to sliding of wheels, reduces efficiency of braking and reduces controllability of the car.
The condition of tires, loading of the car and corners of installation of forward wheels also influence operation of brake mechanisms.