Examination
Mark the position of the wheels on the hubs so that you can later install the balanced wheels in their original positions. Loosen the wheel bolts with the car on the ground. Raise and support the car, remove the wheels.
Note: Measure the thickness of the disc at its thinnest point (arrows).
Measure the thickness of the brake disc. In workshops, a special measuring device or micrometer is used for this, since wear creates an edge on the edge of the disc.
You can measure the thickness of the brake disc with a normal caliper, but you need to put hard washers or two small coins under its jaws on both sides of the disc. In this case, you need to subtract the thickness of these two coins (washers) from the total result.
Note: Take measurements at several points on the brake disc.
The dimensions of the brake discs are indicated in the technical data.
If the minimum permissible thickness is reached, replace the brake disc.
If the brake discs are worn down to the minimum thickness, then you can install a set of brake pads one more time.
If there are deep scratches or pits, replace the brake disc.
Install the wheels in accordance with the marks made during removal. Do not lubricate the wheel bolts. Lower the car and tighten the wheel bolts crosswise to 100 Nm.
[This article is based on data from the website: www.bmwman.ru]