12
2. Lubricate the adjuster shaft with DOT 4 brake fluid and
screw the adjuster shaft fully into the piston assembly,
then unscrew one full turn, Figure 22.
3. Install the spring and locator assembly into the adjuster
shaft assembly. Lubricate the piston assembly with new
DOT 4 brake fluid and install the piston assembly into
the cylinder housing. Fit the dust boot onto the housing.
4. Install a new retainer into the override wheel and install
the override wheel and tappet head onto the piston. On
old style A2LS
™
drum brakes, the override wheel had an
internal retainer ring which also locates in a groove in
the neck of the piston, Figure 23. The latest override
wheel still uses the retainer ring but it is positioned further
up the override wheel. The groove in the piston neck has
been deleted.
Note: A new design piston may be used to replace the piston
in older style brakes but the override wheel must also
be changed. Although it would be permissible to fit an
old style piston into a new style brake, it would be a
retro-grade step and is not recommended. Ensure that
the tappet head assemblies are located securely on
the piston necks.
IMPORTANT: Do not turn the manual override wheel.
5. Repeat the above procedure for the other wheel cylinder.
6. Install the wheel cylinder unit to the backing plate
(dirtshield) using a new gasket, Figure 1, and secure in
place with fixing bolts. Install the bridge pipe and
hydraulic brake hose.
7. Install the brake shoes following procedures under Brake
Shoe Installation in this manual. Refer to the vehicle
service manual for procedures to bleed the air from the
brake system. After bleeding, manually readjust the
brake shoe to drum clearance as necessary. Refer to
Brake Shoe Adjustment in this manual.
BRAKE SHOE INSTALLATION
High temperature grease should be used on those external
parts that require lubrication (slots on the pistons and
tappets, and on the steady posts).
Always install new brake shoes in axle sets. When installing
new brake shoes also install new shoe return springs.
1. Lightly smear the abutment ends of the brake shoes
and steady posts with high temperature grease. Keep
the grease away from all hydraulic components and
the shoe linings. Refer to Figure 24 for correct position
of the replacement brake shoes and shoe return springs.
Note: The color of the spring identifies its position in the
brake assembly.
FIGURE 25 - USING TOOL TO ATTACH SPRING
SPRING TOOL
(REFER
FIGURE 13)
FIGURE 24 - POSITION OF BRAKE SHOE RETURN SPRINGS
LEFT HAND
BRAKE ASSEMBLY
RED ON LH &
RH BRAKES
GREEN ON LH
BRAKE YELLOW
ON RH BRAKE
FIGURE 26 - BRAKE SHOE INSPECTION HOLE
LINING
INSPECTION
HOLE
BRAKE LINING
