Chevrolet 70 1969 Series, Shop Manual

Page: 621 / 913

POWER BRAKE 5-12
9 10 11 12 13 14 15
/
17 18
/ I
25 26 27 28 29 30
1 Pedal Pad
2 Lock Washer
3 Nut
4 Pedal Lever
5 Lock Nut
6 Roller
7 Pedal Lever Pin
8 Retaining Screw
9 Pedal Bracket
10 Snap Ring________
11 Spring Retainer
12 Reaction Ring
13 Upper Shim
14 Spring
15 Lower Shim
16 Piston
17 Block Vee
18 O-Ring
19 Piston Return Spring
20 Shoulder Bolt
21 Cotter Pin
22 Stop Screw
23 Lock Nut
24 Application Valve Body
25 Exhaust Valve
26 O-Ring
27 Valve Return Spring
28 O-Ring
29 Valve Cage
30 Snap Ring T-
F igure 7 — A p p lica tio n V a lv e C o m p o n e n ts ( M - R M o d e l N -4 173)
C A U TIO N : H old bracket firm ly so piston return
spring does not cause bracket to fly o ff assem ­
bly w h en screw s are rem oved.
4. Rem ove piston, O-ring and block vee as an assembly.
5. Remove piston return spring from valve body.
6. Turn valve over and remove snap ring which retains
valve cage.
7. R em ove valve cage and O-ring as an assembly.
8. Rem ove valve return spring.
9. Rem ove exhaust valve and O-ring as an assembly.
Remove O-ring from valve.
10. Disassemble piston assembly.
a. Rem ove O-ring and block vee.
b. Place piston assembly in vise to control pressure
of spring.
c. Remove snap ring.
d. Open vise slowly to relieve spring pressure.
e. Rem ove spring retainer, spring, reaction ring,
upper shim (if present) and lower shim (if pre­
sent).
ASSEMBLY (Refer to Fig. 7)
1. Assem ble piston assembly (refer to fig. 8):
a. Install as m any lower shims as required to ob­
tain a spring preload of 68 to 73 pounds in
assem bled position.
b. Install as m any upper shims as required to ob­
tain a clearance of .170 inches to .180 inches
between upper surface of reaction ring and lower
surface of spring retainer.
c. Place spring in position in piston.
d. Install reaction ring and spring retainer.
e. C om press spring in vise and install snap ring.
f. Install O-ring and block vee on piston assembly.
2. Install piston return spring in valve body.
3. Install piston in valve body, com press spring and in­
stall snap ring.
4. Install O-ring on exhaust valve
1 Spring Retainer 5 Reaction Ring
2 Spring 6 Shim (As Req'd.)
3 Snap Ring 7 Shim (As Req'd.)
4 Piston
t
-2771
Figure 8 — A p p lic a tio n V a lv e Piston A sse m b ly (M - R )
CHEVROLET SERIES 70-80 HEAVY DUTY TRUCK SHO P M A N UA L