Chevrolet 70 1969 Series, Shop Manual

Page: 244 / 913

BRAKES
5B-S1
Figure 22— Rear Brake Shoe Anchor Pin Installation
Whenever any part of the brake assembly has
been removed and replaced, adjust brakes as di­
rected under "Brake Adjustments."
C A M S H A F T A N D M O U N T IN G
Rear brake camshafts have constant lift, S-
type cams forged integral with shaft. Camshaft is
carried in a bushing in brake spider at outer end,
and in a bushing in camshaft and brake chamber
bracket at inner end. Camshaft and brake chamber
bracket is bolted to brake spider in conjunction
with the brake dust shield. Lubrication fitting in
bracket provides a means of lubricating both bush­
ings; space between bushings serves as a lubricant
reservoir. Seals, in outer end of camshaft bore in
brake spider and in inner end of bracket, retain
lubricant and exclude dirt. Apply lubricant at in­
tervals indicated in L U B R IC A T IO N (SEC. 0).
C A U T I O N : Do not overlubricate camshaft, as
excess lubricant may be forced by the seals into
the 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. On the brake
assembly shown in figure 21, the two spacers (11)
are the same; on some models equipped with off­
set slack adjusters, the inner spacer is thicker
than the outer spacer. Whenever camshaft has been
removed, coat bushing surfaces with S-17 Special
Lubricant or equivalent before installing. After
installation, apply lubricant as directed in LUBRI­
C A T IO N (SEC. 0), and adjust brakes as directed
under "Brake Adjustments."
BRAKE DRUMS
Brake drum installations are illustrated in
"R E A R HUBS A N D BE A R IN G S" (SEC. 4C) and in
" F R O N T HUBS A N D BE A R IN G S" (SEC. 3D). By
referring to the illustrations in the above sections,
methods of replacing brake drums are readily
discernible.
Whenever brake drums are removed for serv­
icing brakes, inspect drums. If found to be scored,
rough, or out-of-round, drums should be machined.
Machining or grinding • of brake drums in­
creases the inside diameter of the drum and chang­
es the lining to drum fit. When machining drums,
it is recommended that the following maximum
oversizes not be exceeded:
(a) Drums with standard diameter up to 14"
can be machined up to .060" oversize.
(b) Drum s with standard diameter over 14"
can be machined up to .080" oversize.
When it is found that machining to these m ax­
imum limits does not provide a suitable braking
surface, discard the worn drum and replace with
a new standard drum.
D O N O T E X C E E D T H E S E LIM ITS, THIS IB A
S A F E T Y P R E C A U T IO N .
CHEVROLET SERIES 70-80 H EAVY DUTY TRUCK SH O P M AN U AL