34 21 947 Precision-turning both rear brake discs on both sides (2' Series coupe and convertible, 2017-2021)
Attention!
Always precision-turn both sides of both brake discs on one axle.
Maximum machining dimension per friction ring side is 0.8 mm!
Minimum brake disc thickness (MIN TH)
Brake discs of M models (Compound brake discs) must not be machined!
Only one brake pad set may be used up on brake discs which have been lathe-turned to minimum thickness (MIN TH).
Mobile brake disc lathe:
Attention!
Only BMW-approved brake disc lathes may be used!
In the case of mobile brake disc lathes, the BRAKE CALIPER and the caliper carrier must be removed.
The brake discs remain on the vehicle.
Please refer to the equipment manufacturer's operating instructions for the exact procedure.
After fine-grinding the brake discs, measure the thickness difference inside the braking surfaces at 8 points with an caliper gauge.