Master Cylinder Re-Assembly; Bleeding The Master Cylinder - TUG MZ Operation Maintenance & Parts Manual

Chapter 3
Section 4
2. Check all recesses, openings and internal passages to be sure they are open and free of
foreign matter.
3. Inspect the hydraulic master cylinder bore for etching, pitting or rust. Replace the master
cylinder if any of these conditions exist.
D.

MASTER CYLINDER RE-ASSEMBLY

1. Remove the master cylinder from the vise. Check the outlet ports for brass burrs and
remove, if present.
2. Dip all the parts except for the cylinder body in clean DOT 3 extra heavy duty brake fluid or
equivalent and lubricate the bore walls with brake fluid.
3. Assemble the secondary cup and O-ring back-to-back in the grooves near the end of the
secondary piston. Assemble the cup protector, primary cup, spring retainer and secondary
piston return spring on the other end of the secondary piston.
4. Wet seals with brake fluid, and install the secondary piston assembly in the master cylinder.
Use caution when inserting the piston assemblies into the bore to prevent damage to the seals.
5. Install the primary piston assembly in the master cylinder. Push the primary piston inward
and tighten the secondary piston stop bolt to hold the secondary piston in the bore.
6. Position the stop plate and snap ring on the primary piston. Depress the primary piston and
install the snap ring in the cylinder body.
7. Bleed the master cylinder.
E.

BLEEDING THE MASTER CYLINDER

Before installing the master cylinder on the vehicle, bleed the unit as follows:
1. Support the master cylinder body in a soft-jawed vise and fill both fluid reservoirs with DOT 3
extra heavy duty brake fluid or equivalent.
2. Install plugs in the front and rear brake outlet ports. Bleed the rear brake system first.
3. Loosen the plug in the rear brake outlet port. Depress the primary piston slowly to force the
air out of the master cylinder. Tighten plug while piston is depressed to prevent air from
entering the master cylinder.
4. Repeat this procedure until air ceases to exit at the outlet port.
3-4-2
Orig
MZ Tow Tractor
CD373