Checking the condition of the brake discs and rotor (Audi A4 B6)

For this check, you need to remove the front wheels. When checking the condition of the brake discs, be sure to also inspect the brake linings. A flashlight, mirror, and calipers will help you with this. At the same time, by rotating the brake disc, check the rotor for dirt and damage.

Brake disc sizes (excerpt)

Type	Diameter	Thickness	Wear limit
FN 3 (front brake)	288 mm	25 mm	22 mm
From 54 (front brake)	280 mm	22 mm	20 mm
From 38 (rear brake)	245 mm	10 mm	8 mm

1. A bluish coloration of the disc is normal.

2. Pay attention to the scratches in the discs. The scratches are caused by dirt or excessively worn pads. The scratches should not be too deep.

3. Brake discs cannot be reworked. In case of deep scratches or excessive wear, replace both discs at once.

4. The best way to measure the thickness of the discs is as follows. Place a coin between the caliper and the brake disc, this will allow you to accurately determine the thickness of the disc even in the case of severe wear. Naturally, the thickness of the coin must be subtracted from the obtained value. Measure the disc in several places, taking the smallest thickness value as the basis.



5. Replace discs that are too thin (in pairs).