Attention: Remember that the dust generated during the operation of the brake mechanisms may contain asbestos, which is extremely harmful to human health. Never blow off dust with compressed air or inhale it; when servicing mechanisms, wear a protective mask or respirator. Never use gasoline or petroleum-based solvents to clean brake system components - use only branded cleaners or methyl alcohol!
1. The condition of the components of the brake system, in addition to regular checks specified in the routine maintenance schedule, should be evaluated each time the wheels are removed or if signs of a malfunction of the brake system appear.
2. The following symptoms may indicate a malfunction of the brake components:
- a) When braking, the car loses directional stability (pulling to one side);
- b) During braking, the brake mechanisms emit a screech or creak;
- c) Excessive travel of the foot brake pedal;
- d) When depressing the brake pedal, pulsations are felt;
- e) There are signs of a brake fluid leak (usually on the inner surface of wheel rims and tires).
3. Loosen the wheel bolts.
4. Jack up and support the car on supports or raise it on a lift.
5. Remove the wheels (see chapter «Introduction»).
Disc brakes
6. Each brake caliper is equipped with two pads (internal and external). When the wheel is removed, there is sufficient access to inspect and check the outer brake pad. Assessment of the residual thickness of the friction lining of the inner pad is made visually through the viewing window of the caliper (see resist. illustration) after removing the wheel.
7. The measurement of the residual value of the brake pads is made using a ruler. lining thickness (without taking into account the thickness of the metal substrate) should be at least 2 mm. If the pads are worn out beyond the permissible limit, it is necessary to make a comprehensive replacement of the brake pads.
Attention: All brake pads of one axle must be replaced at the same time, even if only one of them has reached the wear limit!
8. If there is any doubt about the condition of the lining or there is a need for a more detailed inspection of the brake pads, remove the caliper (s) and remove the pads for a more detailed study (see chapter 9).
9. After the pads are removed from the caliper, clean them with a special tool and check the remaining thickness of the pads with a ruler or a vernier caliper equipped with a vernier.
10. Measure the thickness of the brake discs with a micrometer. Compare measurement results with regulatory requirements (see specs). If the thickness of any of the discs is out of range, replace it (see chapter 9). If the thickness of the disc is normal, check its general condition. Pay attention to defects such as deep scratches, grooves, scuff marks, overheating marks, etc., if necessary, remove the disc and give it to the groove (see chapter 9).
11. Before replacing the wheels, inspect all brake lines for signs of damage, wear, deterioration due to aging of the material, signs of leakage, bends, twists and other deformations (in particular near the points of connection of flexible brake hoses to brake calipers. Check up reliability of fastening of hoses collars. Make sure that none of the brake hoses come into contact with sharp corners of adjacent bodywork, exhaust system components and suspension (at any position of the steering wheel). If necessary, make appropriate repairs or correct the route of laying the lines. Replace defective components (see chapter 9).
12. There is a practical way to calculate the range of brake linings, to plan for their timely replacement. When operating a vehicle in difficult conditions (urban cycle, mountainous area, etc.) For front disc brakes, 1mm of pad wear is approximately equivalent to 1,000km. Then, for example, with a thickness of 5 mm, the brake lining will last at least another 3,000 km. Under normal operating conditions, the pads last much longer.
13. At the end of the check, install the wheels in place, paying attention to the direction of the tread pattern, tighten the wheel bolts, lower the car and tighten the bolts in a diagonal order with the required force (110 Nm).
Vacuum booster
14. Check of serviceability of functioning of the vacuum amplifier of brakes is made from a driver's seat.
15. With the foot brake pedal fully depressed, start the engine - the pedal should fall a little more.
16. With the engine running, depress the foot brake pedal several times. The amount of pedal travel must remain constant.
17. Depress the pedal, turn off the engine and continue to hold the pedal down for about 30 seconds more, during which it should not fall down or rise.
18. Start the engine again, let it run for a minute, then turn it off again. Again, firmly depress the pedal several times - the amount of travel should decrease with each stroke.
19. In the event of a negative result of the described test, the servo drive of the vacuum brake booster must be replaced (see chapter 9).
Parking brake
20. The parking brake is applied using a lever installed between the front seats. Checking the operation of the parking brake mechanism is carried out on a fully suspended vehicle - the wheels must be at least 5 cm above the ground. Before starting work, make sure that the car is securely fixed.
21. Fully release the parking lever and manually check the free rotation of the wheels.
22. Engage the parking brake lever 2 clicks - with free rotation, the wheel should immediately brake, but with effort it will be difficult to turn. Both wheels must be braked with the same force.
23. Engage the parking brake lever 3 clicks - now the rear wheels should not spin.
24. If the above conditions are not met, make the necessary adjustments (see chapter 9).
25. After inspection/adjustment, lubricate parking brake drive cable guides with Opel Silicone Grease - 19 70 206 (90 167 353) and lower the car.
26. Alternatively, checking the proper operation of the parking brake can be done by parking the car on a sloping section of the road and fixing it with a stationary parking brake with the transmission in neutral. If the brake does not hold the vehicle when cocking its lever to the required number of clicks, it is necessary to make an adjustment (see chapter 9).
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