Chevrolet 70 1969 Series, Shop Manual

Page: 243 / 913

BRAKES 5B-50
“S” CAM REAR BRAKES
Wagner " S ” cam brake assemblies are used
on rear axle of all tilt cab models. All conven­
tional cab models use "Stopmaster” brakes at
rear axle. Brake assembly can be removed as a
complete assembly; however, the various' com ­
ponents must be replaced individually. Brake
assembly shown in figure 21 is a typical Wagner
brake assembly,
B R A K E SH O ES A N D A N C H O R PINS
(Refer to Fig. 21)
Refer to " R E A R HUBS A N D B E A R IN G S" (SEC.
4C) for removal of wheels, hubs, and brake drums
for access to brake shoes.
Each brake shoe consists of a shoe table with
two shoe webs welded in place. At anchor end,
shoe webs straddle the mounting flange on brake
spider and pivot on anchor pins. Anchor pins are
held in place by a lock ring at each end. A leather
seal is used between lock ring and shoe web at
outer end and between dust shield and shoe web at
inner end to retain lubricant and exclude dirt. Shoe
ends are not equipped "with bushings; if shoes or
anchor pins become worn, parts must be replaced.
Refer to figure 22 for cross-sectional view.
At cam end of each shoe, a roller installed
between shoe webs on a roller pin makes the con­
tact between shoes and cam. Flats on end of roller
pin fit into notches in shoe webs. Tension of brake
shoe return spring holds shoe rollers firmly against
cam. Return spring pins are staked in 8 places so
that they will not slide out of shoe webs. No lubri­
cation is required at rollers or roller pins; parts
should be assembled clean and dry. Anchor pin
ends should be coated with S-17 Special Lubricant
or equivalent during installation.
A two-piece molded lining is riveted to each
shoe. Linings should be replaced before wear ex­
poses the rivet heads and causes damage to brake
drums. Both linings on each shoe are identical and
can be installed at either end. New linings must be
securely riveted to shoe with correct size rivets,
and rivets must be properly upset. Maxim um brak­
ing efficiency can be obtained immediately if lin­
ings are trued-up with lining grinder so they are
properly centralized in relation to center of hub.
15
15
1 Brake Shoe
2 Brake Shoe Return
Spring
Cam (integral with
shaft)
4 Camshaft Seal
Camshaft Bushing
Brake Spider
Dust Shield
Camshaft and Brake
Chamber Bracket
9 Camshaft
10 Snap Ring
11 Spacers
12 Slack Adjuster
13 Lock Ring
14 Anchor Pin
15 Leather Seal
16 Brake Shoe Roller
17 Roller Pin
18 Brake Shoe Lining
TPM-7630
Figure 21— Rear Brake Assembly (Wagner)
CHEVROLET SERIES 70-80 H EAVY DUTY TRUCK SH O P M A N U A L