Chevrolet 70 1969 Series, Shop Manual

Page: 242 / 913

BRAKES 5B-49
shoe. Lining should be replaced before it becomes
worn to the extent that the rivets will damage the
brake drum. Make sure new lining fits firmly
against shoe and that all rivets are properly upset.
When brake drums have been machined oversize,
shims should be used between lining and shoe or
oversize lining used to maintain proper lining-to-
drum contact. Refer to "Brake D ru m s" in this
section. Maximum braking efficiency can be ob-
1 Brake Shoe and Lining
Assembly
2 Anchor Pins
3 Anchor Pin C-washers
4 Brake Shoe Bushing
5 Anchor Pin Lock Nut
6 Backing Plate
7 Camshaft Bracket
8 Camshaft Bracket
Bushing
9 Camshaft
10 Slack Adjuster
11 Slack Adjuster
Spacers
12 Lock Ring
13 Cam (Integral with
shaft)
14 Brake Shoe Return
Spring
15^ Lubrication Fitting
TPM -8228
Figure 20 — Front Brake Assembly (Rockwell)
tained immediately if linings are trued-up with a
conventional lining grinder so they are properly
centralized in relation to center of hub.
Whenever any part of the brake assembly has
been removed and replaced, adjust brakes as di­
rected under "Brake Adjustments."
Anchor Pin Adjustment (Fig. 20)
(F-150 or F-160 Axle Only)
On F-150 or F-160 axles, whenever brakes
have been relined or anchor pin positions changed
for any reason, anchor pins must be adjusted to
properly locate the curvature of the lining to drum
and to obtain proper lining to drum clearance.
Make adjustment as follows:
1. Loosen anchor pin lock nuts and turn pins
to position punch marks as close together as pos­
sible as shown in figure 20.
2. Rotate cam by turning slack adjuster worm
shaft to bring shoe lining into contact with the
brake drum. Rotate anchor pins just enough to
relieve drag. Repeat the adjustment until further
rotation of the anchor pins will no longer relieve
drag.
3. Tighten anchor pin lock nuts. Back off cam
to released position by turning slack adjuster worm
shaft. Adjust brake chamber push rod travel as
directed under "Brake Adjustments."
FRONT BRAKE CAMSHAFTS
Front brake camshafts have constant lift type
cams forged integral with shaft. Camshafts are
mounted in camshaft and brake chamber brackets
which are bolted to backing plate (figs. 19 and 20).
Each bracket is equipped with two bushings and a
lubrication fitting. Space between bushings acts as
a lubricant reservoir. Lubricant should be applied
sparingly at intervals specified in LU B R IC A T ION
(SEC. 0).
C A U T IO N : Do not overlubricate camshaft, as
excess lubricant will be forced into brake drums.
Slack adjuster, mounted on splined end of
camshaft, is held in place by a lock ring. A spacer
is used on each side of slack adjuster. Whenever
camshaft has been removed, coat bushing surfaces
with S-17 Special Lubricant or equivalent before
installing. After installation, apply lubricant as
directed in LU B R IC A T IO N (SEC. 0), and adjust
brake as directed under "Brake Adjustments.”
Refer to " F R O N T HUBS A N D B E A R IN G S" (SEC.
3D) for removal of wheels, hubs, and brake drums
for access to brake shoes.
CHEVROLET SERIES 70 -80 H EAVY DUTY TRUCK SH O P M AN U AL