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

WARNING: This page is about a different car, the 2011 BMW 750xi, 2011 BMW 750Lxi, 2010 BMW 750xi, and 2010 BMW 750Lxi. However, it is still accessible from the selected car via links, so may be relevant.

WARNING: In the following work step, large forces occur at the brake caliper piston (up to more than 2800 N).
Risk of injury!

NOTE: Use repair kit.

Check guide sleeves (5). If necessary, fit repair kit guide sleeve.

Fig 1: Identifying Brake Caliper Guide Sleeves

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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 caliper recess.

Do not grip piston with fingers - risk of trapping!

Fig 2: Removing Piston Out From Connection Bore Using Compressed Air

Courtesy of BMW OF NORTH AMERICA, INC.

Press off dust sleeve (1).

Fig 3: Identifying Piston Dust Sleeve

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Carefully remove sealing ring (1) 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 sealing ring (1).

Installation:

Apply a light coat of Ate brake cylinder paste to cylinder bore, piston and seal.

Fig 4: Removing Sealing Ring Special Tool (00 9 316)

Courtesy of BMW OF NORTH AMERICA, INC.

Fit dust sleeve (1) in annular groove of piston (2).

Press piston into cylinder bore.

IMPORTANT: Do not twist brake piston.

Evenly press dust sleeve (1) onto brake caliper housing as far as it will go.

Installation:

The area between the dust sleeve and the brake caliper 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.

Fig 5: Identifying Dust Sleeve And Piston

Courtesy of BMW OF NORTH AMERICA, INC.