34 21 947 Precision-turning both rear brake discs on both sides
WARNING: This page is about a different variant/trim than selected.
IMPORTANT:
Always precision-turn both sides of both brake discs on one axle.
Maximum machining dimension per friction ring side is 0.8 mm.
Observe 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).
Maximum machining dimension per friction ring side is 0.8 mm.
Observe 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).
Stationary brake disc lathe:
IMPORTANT:
Only BMW-approved BRAKE DISC LATHES may be used.
In the case of stationary brake disc lathes, the BRAKE DISC must be removed.
Refer to the equipment manufacturer's Owner's Handbook for the exact procedure.
Mobile brake disc lathe:
IMPORTANT:
Only BMW-approved BRAKE DISC LATHES may be used.
In the case of mobile brake disc lathes, the brake calipers and brake anchor plates must be removed.
The brake discs remain on the vehicle.
Refer to the equipment manufacturer's Owner's Handbook for the exact procedure.
After fine-grinding the brake discs, measure the THICKNESS DIFFERENCE inside the braking surfaces at 8 points with an external caliper gauge.