GMC 4000 Series Service Manual page 202

Figure 3 8 — Removing Brake Shoe Hold D ow n Pins
5. Remove the brake shoe hold-down springs
and pins by compressing the spring with Tool (J-
22348) and, at the same time, pushing the pin back
through the flange plate toward the tool. Then,
keeping the spring compressed, remove the lock
(C-washer) from the pin with a magnet (fig. 38).
6. Lift off the brake shoe and self-adjuster
lever as an assembly.
7. The self-adjuster lever can now be removed
from the brake shoe by removing the hold-down
spring and pin. Remove lever return spring also.
NOTE: The adjusting lever, override spring
and pivot are an assembly. It is not recommended
that' they be disassembled for service purposes
unless they are broken. It is much easier to a s­
sem ble and disassem ble the brake leaving them
intact.
8. Thread the adjusting screw out of the brake
shoe anchor and remove and discard the friction
spring (not shown in figure 36).
9. Clean all dirt out of brake drum. Inspect
drums for roughness, scoring or out-of-round.
Replace or recondition drums as necessary.
10. Carefully pull lower edges of wheel cyl­
inder boots away from cylinders. If brake fluid
flows out, overhaul of the wheel cylinders is nec­
essary.
NOTE: A slight amount of fluid is nearly al­
ways present and acts as a lubricant for the piston.
11. Inspect flange plate for oil leakage past
axle shaft oil sea ls. Install seals if necessary.
12. Check all flange plate attaching bolts to
make sure they are tight. Clean all dirt and rust
G M C S E R V I C E M A N U A L
T-2726
Figure 3 9 — Brake Shoe and Automatic Adjuster Assem bly
from shoe contact faces on flange plate using emery
cloth.
threads in the anchors.
BRAKE SHOE INSTALLATION
surfaces of brake flange plate and on threads of
adjusting screw.
anchor without friction spring to be sure threads
are clean and screw turns easily. Then remove
screw s, position a new friction spring on screw
and reinstall in anchor.
return spring to brake shoe and position adjusting
lever link on adjusting lever pivot.
blies onto hold-down pins. Insert ends of shoes in
wheel cylinder push rods and legs of friction springs.
the adjusting screw (fig. 39).
HYDRAULIC BRAKES
13. Thoroughly clean adjusting screw s and
1. Put a light film of lubricant on shoe bearing
2. Thread adjusting screw completely into
3. Assem ble self-adjuster assembly and lever
4. Position hold-down pins in flange plate.
5. Install brake shoe and self-adjuster assem ­
NOTE: Make sure the toe o fth esh o eis against
Sec. 5A
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