34 21 812 Overhauling left or right rear brake caliper (brake caliper removed)

WARNING: This page is about a different car, the 2005 BMW 645Ci and 2004 BMW 645Ci. However, it is still accessible from the selected car via links, so may be relevant.

Special tools required:

34 1 132

NOTE: Use original BMW repair kit.

Take off plastic caps (1). Unscrew guide screws (2).

Fig 1: Removing Plastic Caps (Rear Brake)

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Installation:

Only clean guide screws; do not grease. Check guide bolts, replace if necessary.
Tightening torque, refer to 34 21 5AZ in BRAKES - TIGHTENING TORQUES - 645CI .

Dismantle brake caliper and remove brake linings.

Installation:

Press brake lining fully outwards and insert spring (4).

Fig 2: Identifying Insert Spring (Rear Brake)
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WARNING: Danger of injury! In the following work step, large forces occur at the brake caliper piston (up to more than 2800 N).

Carefully force piston out through connection bore with compressed air.

Fig 3: Forcing Piston Out Through Connection Bore With Compressed Air

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To protect piston, place a protective plate (e.g. hard wood or hard felt) in caliper recess.

Do not grip piston with fingers - risk of trapping!

Check guide sleeves (5), fitting repair-kit guide sleeve if necessary.

Fig 4: Checking Guide Sleeves (Rear Brake)

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Remove sealing ring carefully with a plastic needle. Clean cylinder bores and parts with alcohol and dry with compressed air.

Fig 5: Removing Sealing Ring (Rear Brake)

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Thoroughly inspect cylinder bore, piston and flange surfaces. Machining of cylinders and pistons is not permitted.

Installation:

Apply a light coat of Ate brake cylinder paste to cylinder bore, piston and sealing sleeve, refer to OPERATING FLUIDS - BRAKES .

Install sealing cover in rear annular groove of cylinder bore. Press in piston with a hardwood board.

IMPORTANT: Do not tilt piston.

Fig 6: Installing Sealing Cover In Cylinder Bore Rear Annular Groove (Rear Brake)

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Press on dust protection sleeve evenly up to stop with special tool 34 1 132.

Fig 7: Pressing Dust Protection With Special Tool 34 1 132 (Rear Brake)

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Installation:

The area between dust protection sleeve and brake caliper housing must be kept dry so as to ensure correct seating for the dust protection sleeve.
Keep Ate brake cylinder paste or brake fluid away from this area.
Make sure dust protection sleeve is correctly seated on piston.