Special tools required:
WARNING: In the following work step, large forces occur at the brake calliper piston (up to more than 2800 N). Risk of injury!
NOTE: Use repair kit, refer to BMW Parts Service.
Check guide sleeves (5), fitting repair-kit guide sleeve if necessary.
Carefully force piston out through connection bore with compressed air.
To protect piston, place a protective plate (e.g. hard wood or hard felt) in calliper recess.
Do not grip piston with fingers - risk of trapping! Press off dust sleeve (1).
Carefully remove seal (1) with special tool 00 9 316.
Clean cylinder bores and parts with alcohol and dry with compressed air.
Thoroughly inspect cylinder bore, piston and flange surfaces. Machining of cylinders and pistons is not permitted.
Install new seal.
Installation:
Apply a light coat of Ate brake cylinder paste to cylinder bore, piston and seal, Refer to BMW Service Operating Fluids.
Fit dust sleeve (1) in annular groove of piston (2).
IMPORTANT: Do not twist brake piston.
Press piston into cylinder bore.
Evenly press dust sleeve (1) onto brake calliper housing as far as it will go.
Installation:
The area between the dust sleeve and the brake calliper housing must be kept dry. It must not come into contact with Ate brake cylinder paste or brake fluid so as to ensure that the dust sleeve is perfectly seated.
PRECISION-TURNING BOTH REAR BRAKE DISCS ON BOTH SIDES
IMPORTANT: Always precision-turn both sides of both brake discs on one axle.
Observe Max. machining dimension per friction ring side 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.
Please refer to the lathe manufacturer's instruction manual for the exact procedure.
Fig. 59: Identifying Stationary Brake Disc Lathe
Mobile brake disc lathe:
IMPORTANT: Only BMW-approved brake disc lathes may be used!
In the case of mobile brake disc lathes, only the brake calliper has must be removed.
The brake discs remain on the car.
Please refer to the lathe manufacturer's instruction manual for the exact procedure.
Fig. 60: Identifying Mobile Brake Disc Lathe
After fine-grinding the brake discs, measure the thickness difference inside the braking surfaces at 8 points with an external micrometer.
Fig. 61: Measuring Thickness Of Brake Discs