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

Press off protective plugs (1).

Unscrew guide bolts (2).

Installation:

Only clean guide screws; do not grease. Check guide bolts, replace if necessary.

Tightening torque. Refer to BRAKES - TIGHTENING TORQUES .

Fig 1: Identifying Protective Plugs & Guide Bolts

Dismantle brake caliper and remove brake linings.

Installation:

Before installing springs (4), press out brake lining completely.

Fig 2: Installing Springs & Pressing Out Brake Lining

Press out piston with compressed air applied through connection bore.

To protect the piston, fit a protective plate (hardwood, hard felt or similar) in the caliper duct.

CAUTION: 10 bar of compressed air produces a force of approx. 1250 N.

Fig 3: Fitting Protective Plate (Hardwood, Hard Felt Or Similar) In Caliper Duct

Check guide sleeves (5), installing guide sleeves from repair kit if necessary.

Repair kit for guide sleeve.

Fig 4: Identifying Guide Sleeves & Installing Guide Sleeves From Repair Kit

Remove sealing ring carefully with a plastic needle.

Clean cylinder bores and parts with alcohol and dry with compressed air.

Inspect cylinder bore, piston and flange surfaces thoroughly for damage. Machining of cylinders and pistons is not permitted.

Fig 5: Removing Sealing Ring Carefully With A Plastic Needle

Installation:

Apply light coat of ATE brake-cylinder paste to cylinder bore, piston, dust cover and sealing cover.
Install sealing cover in rear annular groove of cylinder bore.
First fit dust cover to piston, insert sealing bulge in front groove of cylinder bore and press in piston using a hardwood board.

CAUTION: Do not tilt piston.

Fig 6: Inserting Sealing Bulge In Front Groove Of Cylinder Bore