Chevrolet 30 Series 1967 Service Manual page 270

BRAKES 5-56
Diaphragm: Examine diaphragm for signs of cracking,
wear or damage. Carefully examine the lower face of the
diaphragm which contacts the the port seat in the cover
for signs of pitting or grooving. Replace diaphragm if
any of these conditions are found.
Cover: Inspect condition of exhaust port seat on cover
for signs of pitting. The seat must be smooth and flat.
If the exhaust port seat shows deep scratches or pitting,
it must be replaced.
Spring Seat: If the spring seat is worn or damaged,
replace with new spring seat.
Repairs
If the exhaust port seat on cover shows scratches or
pitting, it can sometimes be repaired by carefully lap­
ping the seat, using a fine emery cloth on a flat surface
(fig. ).
8 8
Assembly
1. Insert diaphragm into spring seat.
2. Position diaphragm and spring seat in body with
spring in place, install and tighten cover securely.
Testing Rebuilt Unit
If facilities are available, the rebuilt quick release
valve can be tested on a suitable test rack. If such facil­
ities are not available, the valve can be tested on the
vehicle.
Both operating and leakage tests must be made in
either case to make certain the quick release valve meets
the tests outlined under Service Checks.
Installation
1. With attaching bolts, mount quick release valve in
place.
2. Connect air lines to the valve.
3. Be certain exhaust port is open.
SLACK ADJUSTERS
Removal
1. Remove clevis pin attaching brake chamber push rod
yoke to slack adjuster.
2. Remove lock ring and spacer securing slack adjuster
on camshaft. Slide slack adjuster off end of shaft.
Disassembly (Fig. 89)
1. Remove dirt and grease from outside of unit by
washing in a suitable cleaning fluid.
Fig. 88—Lapping Exhaust Port Seat
PUSH LOCK SLEEVE IN TO
DISENGAGE HEAD OF WORM
SHAFT TO MAKE ADJUSTMENT
r .
t
_.
l o c k s l e e v e m u s t c o m e o u t
AND ENGAGE HEAD OF WORM
s h a f t t o l o c k a d j u s t m e n t
Fig. 89—Slack A djuster—Cutaw ay V ie w
1. Lock Sleeve
2. Spring
3. Dowel
4. Lever
2. Cut off riveted ends of rivets attaching cover plates
to body. Drive out rivets and remove cover plates.
3. Remove welch plug from end of worm shaft bore.
Insert a flat end punch into the worm shaft bore and
drive worm shaft out of body and worm.
4. Remove lock sleeve and spring from worm shaft.
Remove gear and worm from slack adjuster body.
Inspection and Repair
1. Wash parts in cleaning fluid and wipe dry.
2. Inspect worm and gear and replace with new parts if
chipped or broken teeth are evident.
3. Inspect worm shaft for wear. Make sure corners on
hex end are not rounded.
4. Inspect bushing in lever arm. If worn, out-of-round,
or otherwise damaged, it must be replaced. To re ­
place bushing, press old bushing out and press new
bushing into place. Bushing must be reamed after
installation to 0.503"-0.504".
5. Examine lock sleeve for cracks or other damage.
Replace if necessary.
. Examine lever (body) for cracks or distortion. If
6
lever is damaged in any way, a new body and bushing
assembly must be used.
Assembly (Fig. 89)
1. Place worm and gear assembly in position in body.
2. Place lock sleeve over worm shaft, with socket-like
end of sleeve at hex end of shaft. Place lock spring
in recess formed by sleeve and shaft.
3. Enter small end of worm shaft through hole in body
and worm. P ress worm shaft into worm and body,
making sure the groove in lock sleeve is aligned with
pin in body. P ress shaft in until distance from small
5. Worm
6. Worm Shaft
7. G e a r
8. C over Plate
CHEVROLET TRUCK SERVICE M ANUAL