Remove the wheel.
Remove the brake caliper assembly.
Attention! There is no need to remove the caliper from the car, so after removing the caliper mounting bolts, secure it with twine or wire to the suspension strut. Do not hang the caliper on the brake hose as this may damage the hose.
Attention! If a brake disc needs to be replaced, replace both to ensure uniform braking. When replacing the brake discs, the brake pads must also be replaced.
Slowly turning the brake disc, visually check its condition on both sides. Brake disc wear from pads must be within acceptable limits. If the disc is cracked, replace the disc.
Pic. 10.5. Using a dial gauge to measure brake disc runout
Use a dial gauge to check brake disc runout (pic. 10.5). Fix the indicator in any convenient place and, turning the brake disc, determine its runout at a small distance from the outer edge. Before checking the runout of the brake disc, make sure that the hub bearing is in good technical condition. If the runout exceeds the maximum allowable and the bearing is in good condition, remove and regrind the brake disc. Some workshops can regrind the brake disc without removing it from the vehicle.
Check the brake disc for cracks, especially around the wheel bolt holes, wear or mechanical damage, and replace if necessary.
Measure the thickness of the brake disc at several points. Due to the fact that there is a step around the perimeter of the brake disc, when measuring the thickness of the brake disc using a caliper, place two coins under its jaws. To determine the true thickness of the brake disc, subtract the thickness of two coins from the caliper reading.
Pic. 10.6. Measuring the thickness of a brake disc using a micrometer
More precisely, you can measure the thickness of the brake disc using a micrometer (pic. 10.6).
If the variation in the thickness of the brake disc exceeds 0.127 mm, pulsations may occur during braking. If the thickness of the brake disc is still sufficient, remove and regrind the brake disc.
Special tools and techniques must be used to remove the brake disc from the hub, so the hub with the brake disc must be removed and taken to a service station for treatment or replacement.