Chevrolet 10 Series 1968, Service Manual

Page: 329 / 713

BRAKES 5-86
CA U TIO N : The chamfered notch on the back
end of the guide must be toward the plunger seal
end of the housing, otherwise the automatic ad­
justment feature will not function. When prop-
erely assembled, if adjusting bolt is turned in
one direction, the brake will adjust and if turned
in opposite direction a ratcheting effect will
result. When assembled wrong, a ratcheting
effect will result regardless of which direction
adjusting bolt is turned.
6. Install spring, gasket and bolt.
7. Install anchor plunger components as described
under "Brake Actuation Components."
8. Install brake shoes and brake chamber as detailed
under applicable procedures.
Initial Adjustment
If a new installation has just been made as described
above, start engine and build up required amount of air
pressure in system. Then pump the brake pedal until the
automatic adjuster system adjusts enough to provide
sufficient brake for safe driving. Final adjustment is
made with the vehicle in motion, by pumping the pedal.
SERVICING STANDARD STOPMASTER
BRAKE CHAMBERS
It is recommended that all brake chambers be re­
moved, disassembled, inspected and thoroughly cleaned
at the time that brakes are relined or at one year periods,
whichever occurs first (also dependent upon type of op­
eration and operator experience). Thorough cleaning,
proper lubrication and replacement of any worn parts on
a preventive maintenance basis will assure proper oper­
ation of the system at all times.
F ig . 122-Autom atic Adjuster Assembled
1. Brake A ir Chamber Assembly
16. Plunger Housing
2. Non-Pressure H alf
17. Anchor Plunger (Solid)
3. Brake Shoe Assembly
18. G uid e Screw
4. Adjusting Bolt Assembly 19. Gasket
5. Id en tification Ring 20. Plunger Seal and Retainer
6. Spanner Nut 21. Roller Retaining Cage
7. Plunger Seal and Retainer 22. Wedge Spring
8. A djusting Pawl (Plunger G uide) 23. Cotter Key
9. Hoi low Cap Screw 24. Washer
10. G asket 25. Wedge Shaft
11. Spring
26. Wedge G u id e
12. A djusting Sleeve (Actuator) 27. Diaphragm Plate (Push Rod)
13. A djusting Plunger 28. Rubber Boot
14. Wedge Spring Retainer 29. Pressure H alf
15. Rol ler
F ig . 123— InstaI ling Adjusting Bolt
Instructions covering the removal and service of
standard chambers follows (Refer to Fig. 124):
Rem oval and Disassem bly
1. Disconnect air lines from chambers.
2. Using a punch, drive lock washer protrusions from
notches in spanner nut and spider housing.
3. Using a spanner wrench or a punch and hammer,
loosen spanner nut which secures air chamber to
brake spider housing.
4. Remove air chamber assembly from brake spider
housing.
5. Remove bolt and nut which secure clamping ring.
6. Scribe a mark across the pressure housing and the
non-pressure housing to assure proper reassembly.
7. Remove diaphragm, rod, boot and guide from hous­
ings.
C leaning and Inspection
1. Clean all metal parts thoroughly, using a suitable
cleaning fluid. Blow dry with air or wipe dry with
cloth. (Do not use solvent on diaphragm.)
2. Examine diaphragm and replace with new part if any
signs of wear or deterioration are evident.
3. Inspect pressure housing for scratches, scores, or
excessive wear. Examine all parts for obstructions
and remove any foreign matter.
4. Examine diaphragm plate rod boot for deterioration
or cracks. If deterioration or other damage is
evident, replace. In order to replace boot it is
necessary to remove the plastic guide from the end
of the rod. If the guide is damaged or worn, it too
CHEVROLET TRUCK SERVICE MANUAL