Specifications
Type - All models are equipped with anti-lock braking system (ABS).
System type - Dual hydraulic circuit with diagonal separation. Vacuum brake booster and ABS are standard. The parking brake on the rear wheels is cable-operated with manual control.
Front brake mechanisms — Disc ventilated.
Rear brakes - Disc (depending on the model, ventilated).
Note: The front brakes are ventilated type. Depending on the brand of the engine, both ventilated and conventional brake mechanisms can be installed on the rear wheels.
Permissible lateral runout of brake discs, mm:
- Front wheels - 0.12
- Rear wheels - 0.03
Permissible furrow depth (scratches), mm — 0.4
The maximum deviation of the thickness of the brake disc, mm - 0.01
Characteristics of brake mechanisms (mm)
| Disc brakes | Front wheels1 | rear wheels2 | |||
| Outer diameter of brake disc | 285 | 302 | 314 | 278 | 292 |
| Thickness of the new brake disc | 25 | 28 | 28 | 12h | 20 |
| Minimum allowable brake disc thickness | 22 | 25 | 25 | 10 | 18 |
| Thickness of new brake pads (with metal backing) | 20.0 | 17.0 | |||
| Minimum allowable thickness of brake pads (with metal backing) | 9.0 | 8.0 | |||
1 Floating caliper
2 Combined caliper
3 One piece brake disc (not ventilated)
General information
The brake system is the most important link in the vehicle traffic safety system. It includes a service brake system and a parking brake. Servicing and repairing brake system components requires care and precision. in the absence of the necessary experience, it is better to entrust the performance of these operations to car service specialists. the service brake system is designed to reduce the speed of the vehicle until it comes to a complete stop and to keep the vehicle from rolling during short stops on a slope. All Vectra-C/Signum models are equipped with a vacuum-assisted hydraulic braking system. It includes the main brake cylinder, vacuum brake booster and disc brakes of the front and rear wheels. To increase reliability, the hydraulic drive of the brake mechanisms is divided into 2 circuits that function independently of each other, each of which is connected to the diagonally located wheels of the vehicle. One brake circuit is connected to the calipers of the right front and left rear wheels, the second - to the calipers of the left front and right rear wheels. In case of failure of one brake circuit, the second continues to work in the same mode, providing adequate braking of the car. Failure of any of the circuits leads to a decrease in braking efficiency and is accompanied by the operation of the corresponding warning lamp on the instrument panel (see chapter «Controls and methods of operation», Section 16).
Fluid pressure for both circuits is generated in the brake master cylinder (GTZ) when pressing the brake pedal. 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 reservoir with a supply of brake fluid. It is common for both the service brake drive and the clutch drive.
To create the required pressure in the hydraulic path, it is necessary to apply considerable force to the brake pedal. In order to facilitate the control of the brake system, a vacuum booster is used. On petrol models, pressing the brake pedal opens a one-way valve, and one of the two servo air chambers is connected to the engine's intake air path. Due to the movement of the air flow in the intake tract, a vacuum is created in the servo chamber. In the other chamber of the servo drive, the air pressure is greater and under its influence, the membrane associated with the GTZ rod begins to move and creates the necessary additional force. On diesel models, a special vacuum pump is used to create a vacuum in the servo drive chamber, which is mounted on the engine head and is driven from the timing camshaft.
Note: The Z22YH gasoline engine is also equipped with a vacuum pump.
Brake pads with friction linings are the executive component of the brake system - braking efficiency depends on their condition and the condition of the brake discs. For each car model, taking into account the configuration, the pads of the corresponding brand are designed - the installation of other pads can lead to a change in the vehicle's handling characteristics, a decrease in braking efficiency and, ultimately, to an accident. Some braking tips and tricks are given in Chapter «Controls and methods of operation».
Tightening force of threaded connections, Nm
Hollow bolt of fastening of a brake hose to a support — 40
Union nut of the nipple connection of the brake hose - 16
Bolts for fastening the guide pins of the calipers - З0
Bolts of fastening of directing forward brake mechanisms — 230
Bolts of fastening of directing back brake mechanisms — 130
Screws of fastening of brake disks — 7
Brake pedal assembly fastening nuts - 20
Nuts for fastening the brake lines to the GTZ - 16
GTZ fastening nuts - 50
Bolts of fastening of the brake booster - 20
Nuts of fastening of the lever of a parking brake — 10
Wheel bolts - 110
Precautionary measures
Some special precautions should be observed when servicing vehicle brake system components:
- a) Brake fluid is poisonous, do not allow it to enter the body!
- b) Brake fluid is extremely chemically aggressive - in case of accidental contact with eyes and painted surfaces of body panels, immediately wash it off with plenty of running water!
- c) Use only the correct grade of hydraulic fluid to fill the brake system (see chapter 1). Do not use hydraulic fluid that has stood for more than one year or has been stored in a loosely closed container to add to the system;
- d) Friction linings of brake pads/shoes may contain hazardous asbestos. Try not to inhale brake dust, do not blow it off with compressed air. Never use gasoline or petroleum-based solvents to clean brake system components - use only branded cleaners;
- e) 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;
- f) At the slightest sign of a malfunction in the functioning of the brake system, the operation of the car should be suspended!
- g) When servicing any part of the system, proceed carefully and methodically, with meticulous cleanliness. If you are unsure of the functionality of the components, replace them as a set for both brakes on each axle. Use only spare parts from reputable manufacturers. Upon completion of maintenance and repair work on the brake systems, the following points must be checked each time:
- Are the brake hoses securely attached?
- Are brake hoses and lines in holders?
- Are the bleed valves tight?
- Is there enough brake fluid in the system?
With the engine running, check the tightness of the service brake system. To do this, press the brake pedal with a force of 200 to 300 N (20-30 kg) and hold for 30 seconds - the brake pedal should not fall or drop.
In conclusion, carry out control braking on the road in the absence of vehicles on it.
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