Specifications and description of the brake system (Opel Vectra C)

Specifications

Type - All models are equipped with anti-lock braking system (ABS).

System type - Dual hydraulic circuit with diagonal division. Vacuum brake booster and ABS - standard equipment. Parking brake drive on the rear wheels is cable-operated with manual control.

Front brakes - Ventilated disc.

Rear brakes - Disc (depending on the model, ventilated ones can be installed).

Note: The front brakes are ventilated. The rear wheels may be equipped with either ventilated or conventional brakes, depending on the engine brand.

Permissible lateral runout of brake discs, mm:

• Front wheels - 0.12
• Rear wheels - 0.03

Permissible depth of grooves (scratches), mm — 0.4

Maximum deviation of brake disc thickness, mm — 0.01

Brake characteristics (mm)

Disc brakes	Front wheels¹			Rear wheels²
Brake disc outer diameter	285	302	314	278	292
Thickness of the new brake disc	25	28	28	12s	20
Minimum permissible thickness of the brake disc	22	25	25	10	18
Thickness of new brake pads (with metal backing)	20.0			17.0
Minimum permissible thickness of brake linings (with metal backing)	9.0			8.0

¹ Floating type brake caliper
² Combined brake caliper
³ Solid brake disc (not ventilated)

General information

The brake system is the most important link in the vehicle safety system. It includes the service brake system and the parking brake. Maintenance and repair of brake system components requires accuracy and precision. If you do not have the necessary experience, it is better to entrust these operations to car service specialists. The service brake system is designed to reduce the vehicle speed 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 hydraulic brake system with vacuum booster. It includes a master brake cylinder, a vacuum brake booster and disc brakes of the front and rear wheels. To improve reliability, the hydraulic drive of the brake mechanisms is divided into 2 circuits operating independently of each other, each of which is connected to 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 one continues to operate in the previous 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 activation of the corresponding control lamp on the instrument panel (see Chapter "Controls and operating techniques", Section 16).



Fluid pressure for both circuits is created in the master brake cylinder (MBC) when the brake pedal is pressed. The MBC is mounted on the brake booster servo assembly, which is secured to the rear bulkhead of the engine compartment. A reservoir with a reserve of brake fluid is located on top of the cylinder. It is common for both the service brake system drive and the clutch drive.

To create the required pressure in the hydraulic circuit, it is necessary to apply significant force to the brake pedal. In order to facilitate control of the brake system, a vacuum booster is used. On gasoline models, when the brake pedal is pressed, a one-way valve opens, and one of the two air chambers of the servo drive is connected to the intake air tract of the engine. Due to the movement of the air flow in the intake tract, a vacuum is created in the servo drive chamber. In the other chamber of the servo drive, the air pressure is greater and under its influence, the membrane connected to the master cylinder 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 installed on the engine head and is driven by the timing camshaft.

Note: The Z22YH petrol engine is also equipped with a vacuum pump.

Brake pads with friction linings are the executive component of the braking system - the efficiency of braking depends on their condition and the condition of the brake discs. Each car model, taking into account the configuration, is designed with pads of the corresponding brand - installing other pads can lead to a change in the handling characteristics of the car, a decrease in braking efficiency and, ultimately, to an accident. Some tips and techniques for braking are given in the Chapter "Controls and operating techniques".

Tightening force of threaded connections, Nm

Hollow bolt for fastening the brake hose to the caliper - 40

Union nut of the brake hose union connection - 16

Bolts for mounting the caliper guide pins - 30

Front brake guide mounting bolts - 230

Rear brake guide mounting bolts - 130

Brake Disc Mounting Screws - 7

Brake pedal assembly mounting nuts - 20

Nuts for fastening brake lines to the brake master cylinder - 16

Master cylinder mounting nuts - 50

Brake booster mounting bolts - 20

Parking brake lever mounting nuts - 10

Wheel mounting bolts - 110

Precautionary measures

When servicing vehicle brake components, there are some special precautions that should be taken:

• a) Brake fluid is poisonous, do not allow it to enter the body!
• b) Brake fluid is extremely chemically aggressive - if it accidentally gets into your eyes or on painted surfaces of body panels, wash it off immediately 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 been standing for more than one year or that has been stored in a loose container to add to the system;
• d) Brake shoe/pad friction linings may contain asbestos, which is harmful to health. Avoid inhaling brake dust, and do not blow it off with compressed air. Never use gasoline or petroleum-based solvents to clean brake system components - use only branded cleaning agents;
• e) Ensure that all required tolerances and tightening forces are observed. When servicing components, use only serviceable tools. If in doubt, seek help from specialists. Remember that proper functioning of the brakes is the key to traffic safety;
• f) At the slightest sign of malfunction of the braking system, operation of the vehicle must be suspended!
• g) When servicing any part of the system, proceed carefully and methodically, scrupulously maintaining cleanliness. If you are not sure of the functionality of the components, replace them as a set for both brake mechanisms of each axle. Use only spare parts from well-known manufacturers. After completing the maintenance and repair work on the brake systems, the following points must be checked each time:
• Are the brake hoses securely fastened?
• Are the brake hoses and lines in the holders?
• Are the bleed valves tightened?
• 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 sink.

Finally, carry out test braking on the road when there are no vehicles on it.