Warning! Dust resulting from wear on the linings and accumulating on brake components may contain asbestos that is hazardous to health. Do not blow this dust out with compressed air or inhale it! Do not use gasoline-based solvents to remove dust.
Note. In addition to checks at regular intervals, the condition of the brake mechanisms should be carried out each time the wheels are removed or if signs of a malfunction appear in the brake system. Checking the brake fluid level is described in Section Checking fluid levels, leak control.
Signs of problems in the brake system
Any of the following symptoms may indicate a potential defect in the brake system:
- When depressing the brake pedal while the vehicle is moving "leads away" one way;
- Brake mechanisms during braking make scraping or squealing sounds;
- The brake pedal has excessive travel;
- Brake pedal pulsing (this is normal only when the ABS system is working);
- Brake fluid leaks (usually visible on the inside of a tire or wheel)
If at least one of these signs is found, inspect the brake system immediately.
Brake lines and hoses
Note. The brake system mainly uses metal brake pipes, with the exception of flexible reinforced hoses at the wheels. Regular inspection of all these lines is very important.
1. Park your vehicle on level ground.
2. Jack up the car and place it on jack stands, then remove the wheels. Checking vacuum hoses is given in Section Checking the condition and replacing hoses and tubes in the engine compartment, localizing leaks.
3. Check all brake lines and hoses for cracks and abrasions in their outer coating, as well as leaks, swelling and deformation. Check the brake hoses at the front and rear of the vehicle for signs of softening, cracking, deformation, or wear due to rubbing against other parts. Check all fittings for signs of leaks and make sure all brake line fasteners are secure.
4. Bend the brake hose back and forth with your hands to check for damage. Hoses should not be twisted.
5. Turn a steering wheel to the right and to the left against the stop. Make sure that the hoses do not touch the vehicle structure.
6. If fluid leaks from the brake lines or damage are found, the leaks should be repaired immediately. For a more detailed description of the procedure for repairing the brake system, refer to Chapter Brake system.
Checking the thickness of brake pads and discs
1. Jack up and jack up the vehicle, then remove the appropriate wheel.
Note. Experience shows that due to the presence of dirt on the edge of the road, the wear of the brake pads of the right wheel is greater than that of the left. Therefore, to check it makes sense to remove the front right wheel.
2. Measuring pad thickness front The disc brake is made through a special control window in the caliper. If the pad thickness is less than 2 mm, replace all brake pads on both front wheels.
Note. As a rule, 1 mm of brake pad wear corresponds to at least 1000 km of run under adverse operating conditions. Under normal conditions, the pads are erased much more slowly.
3. To check pad thickness rear (tympanic) jack up the car and inspect the pads from inside the disc. If in doubt, measure the pad thickness with the brake drum removed. If it is less than 1.5mm Replace all pads on both rear wheel brakes.
4. Check brake calipers for leaks. If leaks are found, repair the caliper immediately.
5. Visually check the brake discs and drums on the inside and outside for gouges, rust and cracks. Replace defective components.
6. Measure the thickness of the brake discs in several places using a micrometer or a special caliper. You can also measure the thickness of the brake disc with a conventional caliper by placing a pad of known size on each side of it (e.g. two coins), and then subtracting the thickness of the pads from the measured value.
7. Measure the inside diameter of the brake drums.
8. Compare the minimum result obtained in each case with the requirements Specifications. If the wear limit is reached, be sure to replace both brake discs or drums. The brake disc/drum should also be replaced if there are large cracks or deep grooves on the running surface.
Checking and adjusting the brake and clutch pedals and the parking brake lever
1. Measure the free play (A) and height (H1) released brake pedal.
2. Make similar changes for the clutch pedal.
3. If the measured values do not meet the requirements Specifications, adjust the brake pedal as illustrated. To do this, give the locknut, screw or unscrew the position sensor of the corresponding pedal and secure it with a locknut.
4. Set the parking brake by pulling the lever of its drive with a force of 196 N. At the same time, 11-12 clicks should be heard. Otherwise, adjust the parking brake as described below.
5. Insert a socket wrench into the gap in the parking brake lever and loosen the nut to completely loosen the parking brake cable. Release the parking brake lever.
6. Depress the service brake pedal 2-3 times to select the brake pad clearance.
7. Turn the rear wheels to make sure they run smoothly.
8. Pull the parking brake lever until the adjusting nut is accessible and adjust the parking brake by turning it.
Note. Once the nut has been released, it must not be reused.
9. After cocking the parking brake 3-4 times with a force of 196 N, make sure that it is adjusted correctly. Then, with the parking brake released, check that the rear wheels run smoothly.
Checking the vacuum brake booster
1. With the engine off, depress the brake pedal several times - with each press, its stroke should decrease.
2. With the brake pedal depressed, start the engine - the pedal should go down.
3. Keeping the brake pedal depressed, stop the engine. If the pedal stroke does not change when holding the pedal for 30 seconds, the vacuum booster is in order.
4. If one of the above checks fails, repair or replace the vacuum booster (see chapter Brake system).
Check of tightness of the control valve of the vacuum amplifier
1. Checking is done by connecting a hand vacuum pump to opposite sides of the control valve and creating a vacuum in it.
2. When connecting the pump on the side of the vacuum booster (1) and creating vacuum 66.7 kPa, it can decrease by 1.3 kPa for 15 seconds.
3. When connecting the pump on the motor side (2) vacuum should not occur.