They are metal plates fixed in a certain way on the inner brake pads. As the friction lining wears, the plate gradually approaches the surface of the brake disc. When the minimum allowable thickness of the overlay is reached, the edges of the plate and the disk are in contact. At the moment of braking, a characteristic creaking sound appears. This is a signal that the pads need to be replaced. After the sound appears, you can operate the car, but it is necessary to avoid intensive braking and replace the brake pads as soon as possible.
To prevent the need to replace the pads by surprise, do not wait for the wear indicator to work Before a long trip or when changing wheels, visually check the degree of wear of the brake pads and discs.
You will need: caliper or micrometer, ruler.
1. To check the front brake mechanisms, raise the front of the car with a jack. To prevent accidental starting of the engine, remove the key from the ignition.
Warning: Depending on which part of the vehicle you are lifting, place wheel chocks under the opposite wheels («shoes»).
2. Remove the front wheel.
3. Check the condition of the pads through the hole in the brake caliper housing. If the thickness of the friction linings together with the base is less than the permissible (see table. 9.1), replace the brake pads (see «Replacing the brake pads of the brake mechanism of the front wheel»).
4. Measure the thickness of the brake disc in the area of the working surface. If its thickness is less than the allowable (see table. 9.1), replace the brake disc (see «Replacing the brake disc of the front wheel brake mechanism»).
Table 9.1. Dimensions of brake pads and discs
Parameter | Meaning |
Front wheel brakes | |
Brake disc diameter, mm | 276 |
Brake disc thickness, mm | 26 |
The minimum allowable thickness of the brake disc, mm | 24 |
Thickness of the friction lining of the brake shoe, including the base, mm | 19,8 |
The minimum allowable thickness of the friction lining of the brake shoe, mm | 2 |
Rear wheel brakes | |
Brake disc diameter, mm | 268 |
Brake disc thickness, mm | 12 |
The minimum allowable thickness of the brake disc, mm | 10 |
Thickness of the friction lining of the brake shoe, including the base, mm | 17 |
The minimum allowable thickness of the friction lining of the brake shoe, mm | 2 |
5. Disc surface wears unevenly. A shoulder remains on the outer circumference of the disc, so it is more correct to measure the thickness of the disc with a micrometer.
6. Inspect jumpers A of air channels for disc cooling. If cracks are found in the jumpers, the disk must be replaced.
7. Similarly check up brake mechanisms of the second forward wheel.
8. To check the rear disc brake, remove the rear wheel and check the mobility of the pistons and brake guide pins. Rotating the piston, sink it into the caliper cylinder (use a special tool). If the piston cannot be moved, then it is stuck in the brake cylinder.
In the absence of a special device, use sliding pliers. Push the plunger in by rotating it while applying pressure with your finger. Be careful not to damage the side of the piston.
9. Check the condition of the pads through the hole in the brake caliper housing. If the thickness of the friction linings is less than the permissible (see table. 9.1), replace the brake pads (see «Rear wheel brake replacement»).
10. Measure the brake disc thickness. If its thickness is less than the allowable (see table. 9.1), replace the brake disc (see «Replacing the brake disc of the rear wheel brake mechanism»).
11. Disc surface wears unevenly. A shoulder remains on the outer circumference of the disc, so it is more correct to measure the thickness of the disc with a micrometer (see point 5).
12. Similarly check up brake mechanisms of other back wheel.
Note: Replace pads in the following cases:
- the signal lamp in the instrument cluster lit up due to the operation of the brake pad wear sensor;
- the surface of the pads is oiled;
- pads are loosely connected to the base.