Chevrolet 10 1971 Series Chassis Service Manual page 162

BRAKES 5-14
Fig. 33— Setting Lining Clearance with J—21177
If the lubrication in the adjusting screw of as­
sembly is contaminated or destroyed, the ad­
justing screw should be thoroughly cleaned and
lubricated.
5. Connect brake shoes together with adjusting screw
spring, then place adjusting screw, socket and nut
in position.
Make sure the proper adjusting screw
CAUTION:
is used (left hand or right hand). The star wheel
should only be installed with the star wheel
nearest to the secondary shoe and the adjusting
screw spring inserted to prevent interference
with the star wheel.
6. Install parking brake cable.
7. Secure the primary brake shoe (short lining faces
forward) first with the hold down pin and spring using
a pair of needle nose pliers. Engage shoes with the
wheel cylinder connecting links.
8. Install and secure the actuator assembly and second­
ary brake shoe with the hold down pin and spring
using a pair of needle nose pliers (on rear position
parking brake strut and strut spring).
9. Install guide plate over anchor pin.
10. Install the wire link.
Do not hook
NOTE:
anchor pin stud with the regular spring hook
tool. This may damage the cylinder boot seals.
Fasten the wire link to the actuator assembly
first, and then place over the anchor pin stud by
hand while holding the adjuster assembly in full
down position.
11. Install actuator return spring.
Do not pry actuator lever to install
NOTE:
return spring. Ease it in place using the end of
a screw driver or other suitable flat tool.
12. If old brake pull back (return) springs are nicked,
distorted, or if strength is doubtful, install new
springs.
13. Hook springs in shoes using Tool J-8049 by installing
the primary spring from the shoe over the anchor
pin and then spring from secondary shoe over the
wire link end.
the wire link over the
Fig. 34— Measuring Drum Diameter
14. Pry shoes away from the backing plate and lubricate
shoe contact surfaces with a thin coating of brake
lube.
Be careful to keep lubricant off facings.
CAUTION:
15. After completing installation, make certain the actu­
ator lever functions easily by hand operating the
self-adjusting feature.
16. Follow the above procedure for all brakes.
17. Adjust the service brakes as outlined below, then
adjust the parking brake.
Adjustment
Although the brakes are self adjusting a preliminary
or initial adjustment may be necessary after the brakes
have been relined or replaced, or whenever the length of
the adjusting screw has been changed. The final adjust­
ment is made by using the self adjusting feature.
1. With brake drum off, disengage the actuator from the
star wheel and rotate the star wheel by spinning or
turning with a small screw driver.
Recom m ended M eth od of Adjustm ent (Figs. 32-33)
a. Use special Tool J-21177. Drum to Brake Shoe
Clearance Gauge, to check the diameter of the
drum clearance surface.
b. Turn the tool to the opposite side and fit over the
brake shoes by turning the star wheel until the
gauge just slides over the linings.
c. Rotate the gauge around the brake shoe lining
surface to assure proper clearance.
Alternate M e th od of Adjustm ent
a. Using the brake drum as an adjustment fixture,
turn the star wheel until the drum slides over the
brake shoes with a slight drag.
b. Turn the star wheel 1-1/4 turns to retract the
shoes. This will allow sufficient lining to drum
clearance so final adjustment may be made as
described in Step 4.
2. Install the drum and wheel and remove the vehicle
from the jack stands or hoist.
1: If lanced area in backing plate was
NOTE:
knocked out, be sure all metal has been removed
from brake compartment, install new hole cover
to prevent contamination of the brakes.
10-30 CHEVROLET TRUCK SERVICE MANUAL