This procedure applies to both front and rear brake discs. Brake discs should always be replaced or repaired in pairs (both front or both rear discs), even if only one of them is damaged.
Inspection
1. Loosen the wheel bolts, jack up the vehicle and place it securely on axle stands. Remove the wheel and install three bolts to hold the disc in place. If you are working on the rear brake disc, release the parking brake.
2. Remove the brake caliper as described in Section Removal, overhaul and installation of the disc brake caliper. It is not necessary to disconnect the brake hose. After removing the caliper, hang it on a piece of wire to the side so that it does not interfere with work. Remove the caliper support bracket.
3. Examine the surface of the disc for scratches, cracks, or other damage. Light scratches and shallow grooves are acceptable and usually do not affect brake performance, but deep scratches require removal and replacement of the disc, or, if possible, grooving by a specialist in an auto repair shop. If there are cracks, the disc must be replaced. Don't forget to inspect both sides of the disk.
4. If strong vibrations were noticed during the operation of the brakes, then the disc may be deformed (excessive beat). If your vehicle is equipped with ABS, do not confuse the vibration caused by disc warping with normal ABS operation. During operation of this system, there is usually a slight vibration in the brake pedal.
5. To measure disc runout, set the dial indicator to a point approximately 13 mm from the outer edge of the disc. Set the indicator to zero and rotate the dial. The indicator readings must not exceed the limit set in Table of sizes and adjustment data at the end of the Guide.
6. If they still exceed the set value (and if the runout is not due to wheel bearing wear), the disc should be replaced, or, if possible, honed by a workshop.
It is recommended to grind the discs regardless of the indicator reading to achieve a smooth, flat surface, which in turn will help to avoid brake pedal vibration and other unwanted symptoms associated with the operation of the discs. In case you still decide not to grind the discs, remove at least the gloss from their surface with sandpaper or sandpaper using circular motions.
7. It is very important to ensure that after turning the disc thickness does not become less than the limit value specified in Table of sizes and adjustment data at the end of the Guide. The minimum allowable disc thickness is stamped on the disc hub. The thickness of the disc can be measured with a micrometer.
Withdrawal
1. Loosen the disk fixing screw...
...and remove the disc from the hub.
2. If the disc «stuck» to the hub, spray a generous amount of oil into the area between the hub and the disc and leave for a few minutes to soften the rust between the two components.
3. If the rear disc still does not come off, insert a thin flathead screwdriver through the hole in the hub flange, turn the sprocket on the parking brake adjusting screw, and compress the parking brake shoes.
If «stuck» front disc, then on some discs it is possible to insert two or three bolts into special holes and tighten them. Turn the bolts one by one a couple of turns at a time until the disc is free.
Installation
1. Before installing, make sure that the disk is completely clean. If oil was used to remove the disc, make sure that there are no traces of oil left on it. Mount the disc on the hub and fit the disc mounting screw. Tighten it to the required torque.
2. Install the caliper support bracket (if it was removed), brake pads and caliper (see Sections Replacing disc brake pads and Removal, overhaul and installation of the disc brake caliper). Tighten all fasteners to the required torque.
3. Install the wheel, then lower the vehicle to the ground. Depress the brake pedal several times to bring the brake pads into contact with the disc.
4. Adjust the parking brake shoes if necessary (Chapter Parking brake adjustment).
5. Carefully check up operation of brakes before the beginning of normal operation of the car.