Note: Models 320i, 325e, 325i are equipped with internally ventilated brake discs, while the other models have solid brake discs.
Mark the position of the rims on the front wheel hubs with paint. Thanks to this, the balanced wheel is subsequently set to the same position.
Loosen the wheel bolts of the corresponding rear wheel. In this case, the car must still be on the ground.
Raise the car and remove the wheel.
Measure the thickness of the brake discs. At service stations, a special template or micrometer-bracket is used for this, since when worn, a protrusion forms on the edge of the disc. It is possible to measure the thickness of the disk with a conventional caliper, however, pads of known thickness should be placed under its cheeks, for example, 2 coins of 10 pfennigs). To obtain the true result, subtract 3.3 mm from the measured value of the thickness of the two coins.
Attention: Take several measurements around the disc circumference.
Minimum allowable thickness of brake discs:
- Model 316, 316i, 318i, 320i: (With a massive disk) - 11.1 mm
- Model 320i, 323i, 324d/td: - 20.4 mm
- Model 325e, 325i. M3: - 23.4 mm
When the minimum allowable thickness is reached, install new brake pads one more time.
When the wear limit is reached, the brake disc must be replaced. The wear limit is 0.4 mm less than the minimum allowable thickness.
If there are significant scratches or grooves deeper than 0.5 mm, replace the brake discs.