Attention! If the master cylinder body is damaged, replace the master cylinder assembly. When mounting the master cylinder in a vise, clamp only the protrusion of the master cylinder (pic. 6.28).
Disassembly
Remove the cap and remove the strainer from the brake master cylinder reservoir.
Unscrew the fastening screw and remove the tank.
Remove two o-rings.
Place the cylinder in a vise.
Using a screwdriver, push the pistons all the way, unscrew the lock bolt and remove the O-ring.
Note. Wrap the screwdriver with plaster or adhesive tape so as not to damage the pistons and cylinder bore.
Pic. 6.29. Removing the spring ring
Press the piston with a screwdriver and use the circlip pliers to remove the circlip (pic. 6.29).
Pic. 6.30. Removing the primary piston with spring
Unscrew the locking piston bolt with a gasket and remove the primary piston with a spring, pulling it strictly along the axis without distortion (pic. 6.30).
Note. If the piston is removed at an angle, the cylinder bore may be damaged.
Pic. 6.31. Removing the secondary piston
Place a rag on two wooden blocks and lightly strike the cylinder flange against the blocks until the secondary piston comes out. Make sure the distance (A), indicated in Figure 6.31, from a rag to the top of the bars - at least 100 mm.
Check for rust and scratches on the cylinder mirror.
Check for wear or damage to the cylinder.
If necessary, replace the cylinder.
Attention! Replace all parts in the repair kit used to service the brake master cylinder.
Attention! When installing, lubricate the rubber parts with clean brake fluid to facilitate assembly. Do not use commercial compressed air to dry or clean brake parts. This may damage the rubber parts. If any part of the hydraulic system is removed or disconnected, completely bleed the brake system.
Attention! Perform all repairs on a clean workbench.
Assembly
Install the secondary and primary pistons.
Install a new o-ring on the set screw.
Fully sink the primary piston assembly.
Install and tighten the lock screw.
Tightening torque: 2.0 - 2.4 Nm.
Pic. 6.32. First Check of the Secondary Piston Assembly
Press and release the secondary piston assembly, making sure it is held by the set screw (pic. 6.32).
Install the secondary piston with the hole facing the lock pin and primary piston.
Install a new O-ring on the retaining pin.
Fully sink the primary piston assembly.
Install and tighten the lock pin.
Tightening torque: 6.9 - 9.8 Nm.
Pic. 6.33. Second check of the secondary piston assembly
Press and release the secondary piston assembly, making sure it is held by the set screw (pic. 6.33).