Remove (install) rear brake fixed calliper (34 21 220).
Remove the brake pads.
Take out the clamp rings (1) and rubber protecting caps (2).


34 21 220

Insert a plug in the brake lining connecting hole and
retain the piston in position with the piston return pliers
(3.9314-1800.2).
Insert a felt or hardwood pad between the calliper jaws.
Apply a compressed air jet to the bleed hole to press out
the brake piston.
Warning: Exercise great care! A compressed air supply at
10 atü (142 psi) will generate a force of approx. 250 kp
(550 Ibs.).

Lift out the sealing rings with a plastic needle.

Warning: Components must be cleaned only with brake
fluid or alcohol. Dry with a clean compressed air supply.
Examine cylinder bores and pistons for damage.
Always renew parts if damaged. To simplify assembly,
apply a very thin layer of ATE brake cylinder paste to the
cylinder and piston. This will also prevent corrosion. Insert
the piston carefully into the cylinder bore without jamming.

Using piston gauge 3.9314-0600.1, check the 20° position
of the piston and if necessary turn the piston with the piston
rotating pliers (3.9314-1500.2) to correct.
The 20° cutout on the piston should be next to the point at
which the brake disc enters the brake caliper.

Do not separate the two halves of the fixed calliper unless
a sealing ring on one side has developed a leak.
Clean the sealing faces of both calliper halves with alcohol.
When installing: Make sure that the sealing rings are cor-
rectly positioned.

Warning: The calliper halves are connected together by
means of expansion bolts, which must not be re-used after
removal.
Tighten the bolts in the sequence 1 ÷ 4.