Checking the thickness of the brake disc (pic. 11.30) carry out with the wheel removed.
In this case, it is necessary to use a special caliper, or a regular one, placing hard gaskets on both sides (coins), because a rib is formed on the edges of the disk during operation (bead). The measurement is carried out at several points. From the readings of the caliper it is necessary to subtract the thickness of the two gaskets. Disc parameters must comply with the requirements of the technical characteristics of the brake system (see above). Otherwise, grind the discs or replace them with new ones.