Overhaul

- Remove and install tandem brake master cylinder. Removing and Installing



- Replacement parts are not available for brake master cylinders with a recessed stop pin (ABS).




Important:
- Use repair kit:
(1) spring, (2) support, (3) primary cup, (4) fill-in washer, (5) intermediate piston, (6) separating cup, (7) stop sleeve, (8) spring, (9) screw, (10) push rod piston, (11) stop washer, (12) secondary cup, (13) plastic bushing, (14) circlip, (15) seal, (16) aluminum seal and (17) silicone grease.




- Apply light pressure on push rod piston (10), lift out circlip (14) and unscrew stop screw (18).
- Release push rod piston (10) slowly and pull out.



- Knock out intermediate piston by knocking housing on a piece of wood lightly.
- Clean cylinder housing and other parts not contained in the repair kit with alcohol and dry with compressed air.
- Tandem brake master cylinders with surface damage in the cylinder bore, may not be reused.
- Check whether all connecting, compensating and feeding bores are clean.
- Give cylinder bores a very thin coat of ATE brake cylinder paste.
- Remove large plugs from assembly sleeve.



- Slide short sleeve section on long sleeve pipe far enough that stop washer (11), secondary cup (12), plastic bushing (13), circlip (14), seal (15), aluminum seal (16) and silicone grease (17) can be removed.
- Remove small plugs.
- Clamp cylinder housing in a vise fitted with aluminum jaws.



- Guide assembly sleeve with long sleeve pipe into cylinder bore.



- Push stepped short sleeve pipe into cylinder bore against shoulder and hold.



- Push contents of assembly sleeve into cylinder bore carefully with a suitable mandrel until the intermediate piston touches the bottom of the cylinder.



- Hold intermediate piston against stop firmly and screw in screw (18) with a new aluminum ring (16).
- Tighten stop screw (18) with a torque of 5-8 Nm (3.7-5.7 ft lbs).



- Let push rod piston (10) come back carefully.
- Push on stop washer (11).
- Coat secondary cup (12) with silicone grease and install.
- Let short stepped section of assembly sleeve protrude and slide it over secondary cup (12), while holding cup with two fingers.



- Adjust secondary cup flush with long sleeve pipe and push complete assembly sleeves into cylinder bore.
- Push in long sleeve pipe carefully up to point of resistance.
- Hold long sleeve pipe and pull back short sleeve section.
- Remove complete assembly sleeve.



- Give plastic bushing (13) a light coat of silicone grease and push it on push rod piston in cylinder bore.



- Press in push rod piston (10) and plastic bushing (13).
- Install circlip (14) with special circlip pliers.
- Circlip must have perfect seat in groove of cylinder bore.
- Install new seal (15) before mounting on the brake booster.
- Bleed brakes. Service and Repair