Diagram of the hydraulic brake circuit for non-ABS models
1 - Front brake mechanism; 2 - Rear brake mechanism; 3 - Non-separable pressure limiter; 4 - GTZ
Diagram of the hydraulic brake circuit for models equipped with ABS type LSV
1 - Front brake mechanism; 2 - Rear brake mechanism; 3 - GTZ; 4 - ABS pressure modulator; 5 - Load sensing valve
Diagram of the hydraulic brake circuit for models equipped with DVP type ABS
1 - Front brake mechanism; 2 - Rear brake mechanism; 3 - GTZ; 4 - ABS pressure modulator; 5 - Two-way pressure regulator
All car models covered in this manual are equipped with a hydraulic brake system with vacuum boost. The front wheels are always equipped with disc brakes, while the rear wheels may have both disc brakes (models since 1995. no.), and drum (1993 and 1994 models issue) construction.
All brake mechanisms are equipped with self-adjusters. At the same time, compensation for wear of the brake pads of disc mechanisms (front and rear) is carried out automatically, while special adjustment devices are installed on the drum brake mechanisms, the activation of which occurs when the parking brake is cocked.
Hydraulic system
Dual design equipped with two separate reservoirs of the main brake cylinder (GTZ) allows you to split the hydraulic path into two circuits that operate independently of each other. The latter means that in the event of a failure of one of the circuits, the second continues to operate in the same mode, providing adequate braking of the car. Hydraulic circuits have a diagonal arrangement and the failure of any of them, of course, leads to a decrease in braking efficiency and is accompanied by the operation of a warning lamp on the instrument panel when the foot brake pedal is depressed.
Master brake cylinder (GTZ)
The GTZ is mounted on the brake booster servo assembly mounted on the rear bulkhead of the engine compartment. On top of the cylinder is a large hydraulic fluid reservoir equipped with a plastic cap. The tank is fixed in the cylinder with the help of through bushings and a cylindrical pin.
As mentioned above, the GTZ has a dual design that provides the operation of two independent hydraulic circuits. The fluid pressure in each of the circuits is pumped by an individual piston inside the main cylinder. A two-way control valve installed on the bulkhead of the engine compartment provides the necessary balance of hydraulic forces developed in the brake mechanisms of the front and rear wheels.
Vacuum brake booster
The booster uses the vacuum created in the intake piping to improve the efficiency of the hydraulic brake system. The vacuum booster servo is mounted on the rear bulkhead of the engine compartment inside the latter.
Parking brake
The cable drive of the parking brake is connected to the brake mechanisms of the rear wheels of the car. Arming and releasing the brake is provided by a lever mounted on the center console.
Service
Upon completion of any of the maintenance procedures associated with the removal or disassembly of any of the components of the brake system, it is imperative to check the effectiveness of the brake system, and only after making sure that it is in full working order, start operating the vehicle. Road trials should be carried out on a clean, dry and level road surface.
Check the braking performance of the vehicle at different speeds and different pedal pressures. The car must brake evenly, while maintaining directional stability. Try to prevent premature wheel lockup, which could lead to loss of control.
Keep in mind that factors that affect a vehicle's braking performance include the condition and inflation pressure of the tires, the vehicle's load level, and the correct suspension geometry.
Precautionary measures
Some special precautions should be observed when servicing vehicle brake system components:
- a) Use only DOT 3 grade hydraulic fluid to fill the brake system;
- b) Friction linings of brake pads/shoes may contain hazardous asbestos. Try not to inhale brake dust, do not blow it off with compressed air. To wipe the components of the brake mechanisms, use only special cleaning compounds;
- c) Ensure that all required tolerances and tightening torques of fasteners are observed. When servicing components, use only serviceable tools. At the slightest doubt, seek help from specialists. Remember that the proper functioning of the brakes is the key to traffic safety;
- d) At the slightest sign of a malfunction in the functioning of the brake system, the operation of the car should be suspended!