Application. This procedure applies to both front and rear disc brakes.
Examination
1. Loosen the wheel nuts. Raise the car and place it on stands. Remove the wheel and screw on the wheel nuts, placing washers 3 mm thick under them (they may be needed in order to press the disc to the hub). If the disc is secured with two screws, no nuts are needed. When checking the rear disc, release the parking brake.
2. Remove the caliper (see paragraph 4), however, do not disconnect the hose from it. Take the caliper aside and tie it with a piece of wire.
3. Inspect the surface of the brake disc and make sure there are no scratches or other damage (pic. 5.3). Small scratches and shallow grooves always occur during the operation of the car and do not affect the effectiveness of the brake system, however, in the presence of deep scratches (over 1.0 mm deep) disc grinding is required. Examine both sides of the disc.
4. If the vehicle decelerates unevenly during soft braking, the cause may be the runout of the brake disc. To check disc runout, set dial gauge approximately 15mm from outer edge of disc (pic. 5.4,a). Set the indicator scale to 0 and rotate the brake disc by hand. The indicator readings should not exceed the allowable runout value. If the disc runout exceeds the maximum allowable, grind the disc.
Note. Grinding the disc is useful even when the runout does not exceed the allowable value, since this eliminates the uneven deceleration of the car when braking. If you do not plan to sand the disc, remove the shiny spots on its surface with a circular motion of sandpaper (pic. 5.4b).
5. If the thickness of the disc is less than the minimum allowable, it must not be ground. The minimum thickness of the disc is indicated on its non-working surface (pic. 5.5,a). Measure the disc thickness with a micrometer (pic. 5.5b). Measure the disc thickness at several points.
Removing
6. Remove the caliper (if it hasn't already been done), but do not disconnect the hose from it (see paragraph 4). Remove the two bolts securing the caliper bracket to the steering knuckle (pic. 5.6,a) or, for the rear brake, the bracket-to-lever bolts (pic. 5.6b).
7. Remove the wheel nuts (if they were used to fix the drive) or two brake disc mounting screws (pic. 5.7a) and remove the disc from the hub. If the disc is not removable, screw two bolts into the special holes (pic. 5.7b) and tighten them. Evenly screwing both bolts, wring out a disk from a nave.
Installation
8. Install the disc on the wheel studs. Insert the disk mounting screws and tighten them securely.
9. Install the caliper bracket, pads and caliper. Tighten the bracket and caliper mounting bolts to the required torque. If you are installing a rear disc, adjust the wheel cylinder piston (see paragraph 3).
10. Install the wheel and lower the vehicle. Press the brake pedal several times until the pads touch the disc. If you have not disconnected the hose from the wheel cylinder, the hydraulic system does not need to be bled. Check the effectiveness of the brake system before driving.