GMC 4000 Series Service Manual page 203

Sec. 5A
Page 196
HYDRAULIC BRAKES
Figure 4 0 — M ea surin g Points for Brake Shoe Centering
6. Install cup, spring, and retainer on end of
hold-down pin. Using Tool (J-22348) com press the
spring. With spring compressed, push the hold-
down pin back through the flange plate toward the
tool and install the lock on the pin.
7. Using Tool (J-22348) install brake shoe
return springs.
8. Holding the star wheel end of the adjusting
lever as far as possible past the star wheel, posi-
Figure 41 — Positionin g A djusting Lever
G M C S E R V I C E M A N U A L
tion the adjusting lever cam into the adjusting
lever link and assemble with cap screw.
by measuring the distance from the lining surface
to the edge of the flange plate at the points shown
in figure 40. To center the shoes, tap the upper or
lower end of the shoes with a plastic mallet until
the distances at each end become equal.
above the outside diameter of the adjusting screw
thread by loosening the cap screw and turning the
adjusting cam.
adjusting screw 2 full turns out from the fully re­
tracted position. Hold a 0.060" wire gauge at a 90°
angle with the star wheel edge of the adjusting
lever. Turn the adjusting cam until the adjusting
lever and threaded area on the adjusting screw
just touch the wire (figs. 41 and 42).
retract the adjusting screw.
ward and reverse stops until a satisfactory brake
pedal height results.
Figure 4 2 — Wire G a u g e Position for Correct
Adjusting Lever Adjustment
9. Check the brake shoes for being centered
10. Locate the adjusting lever 0.020" to 0.039"
NOTE: To determine 0.020" to 0.039", turn the
11. Secure the adjusting cam cap screw and
12. Install brake drums and wheels.
13. Adjust the brakes by making several for­