GMC 4000 Series Service Manual page 264

1 Plate Locating Pin
2 Primary Shoe
and Lining
3 Brake Lever
4 Return Spring
5 Lever Strut
Pin
6
7 Clip
Backing Plate
8
9 Guide Plate
10 Reinforcement
11 Anchor Pin
12 Lock Washer
13 Anchor Pin Nut
Figure 3 — Internal-Expanding Parking Brake
from reinforcement. Remove pin from backing
plate by threading it from nut. Remove reinforce­
ment and washer with anchor pin.
10. If necessary to remove cable, compress
tangs on cable lock and pull assembly out of hole
in backing plate.
11. If necessary to remove backing plate, re­
move transmission flange nut and transmission
output flange. Remove bolts which fasten backing
plate to bearing retainer and remove backing plate.
INSTALLATION
1. Place backing plate in position on rear
bearing retainer and fasten with four bolts. Torque
bolts to 20-26 foot-pounds.
2. Install transmission output flange on spline
of mainshaft and fasten with flange nut. Torque nut
to 80-120 foot-pounds.
G M C S E R V I C E M A N U A L
14 Secondary Shoe
and Lining
15 Strut Spring
16 Backing Plate Bolts
17 Cable Bracket
18 Cable Assembly
19 Socket
20 Adjusting Screw
21 Nut
22 Connecting Spring
23 Washer
24 Spring
25 Cup
26 Hold-Down Pin T
-5279
3. Install cable assembly from back of back­
ing plate. Push retainer through hole in backing
plate until tangs securely grip inner side of plate.
4. Place washer and reinforcement over the
threaded end of anchor pin. Hold anchor pin nut
(flat side against flange on backing plate) in posi­
tion behind backing plate and insert threaded end
of anchor pin from front side. Thread anchor pin
into nut and tighten securely. Bend tang of washer
over reinforcement and side of washer over hex
of anchor pin.
5. Install lever on cable by compressing spring
and inserting cable in channel of lever. Release
spring.
. Install primary shoe (the one with the short
6
lining) to lever as follows: Place pin in lever with
head of pin toward backing plate. Place washer on
pin and push pin through hole provided in primary
shoe. Fasten parts together by installing clip in
groove of pin.
7. Fasten two brake shoe and lining assem ­
blies together by installing adjusting screw and
nut assembly and connecting spring. Lubricate
adjusting screw sparingly before assembly with
S-17 Special Lubricant.
. Lubricate the six bearing surfaces on the
8
backing plate with a heavy grade of S-17 Special
Lubricant.
9. Place brake shoe and lining assem blies in
position on backing plate.
NOTE: When facing the brake assembly the
shoe with the short lining (primary) should be to
the left with the lever assembled to it.
10. Pull brake shoes apart and install lever
strut and strut spring between the secondary shoe
and the lever. The loop on the strut spring should
be in the "up" position.
11. Hold shoe and lining assem blies in posi­
tion and fasten to backing plate by inserting pin
through back side of plate. Then, install washer,
hold-down spring, and cup (in that order) on hold-
down pin.
12. Place guide plate on anchor pin.
13. Install the two pull-back springs.
14. Before installing brake drum, remove the
two "knock-out" plugs and replace with rubber
plugs as used on standard service brakes with
screw-type adjustment. This will provide holes for
adjustment without the necessity of removing drum.
Install brake drum and propeller shaft yoke.
15. Connect propeller shaft as instructed in
"PROPELLER SHAFTS" (SEC. 4D) in this Manual.
Sec. 5C
Page 254C
PARKING BRAKES