Chevrolet 1991 Light Duty Truck Repair Manual page 333

8. Primary Piston Bearing
9. Rear H ou sing
10. Front H ou sing
11. Return Spring
38 Power Piston
Group
Figure 26— Booster Inner Components
Inspect
• All parts for corrosion, nicks, cracks, cuts, scoring,
distortion or excessive wear. Replace parts as nec­
essary.
• Use crocus cloth to polish away minor corrosion of
the housings or diaphragm support.
^ Clean
• All parts, except the power piston and pushrod
in clean denatured alcohol.
assembly
• Dry all parts cleaned with dry, filtered and unlubri­
cated compressed air.
Install or Connect (Figures 25 through 29)
0
Tools Required:
J 23456 Power Brake Booster Disassembly
and Reassembly Fixture
J 28458 Power Piston Seal Protector
1. Lubricated O-ring (31) with a thin layer of silicone
grease and install onto the air valve pushrod
assembly (32).
2. Air valve pushrod assembly (32) into the power
piston (33).
3. Retainer (30) and seat.
4. Filter (29) over the pushrod eyelet and into the
power piston (33).
5. Retaining ring (28) onto the air valve pushrod
assembly (32).
6. Reaction bumper (27) and air valve spring (26).
12. Piston Rod
(Gaged)
13. Reaction
Retainer
14. Power Head
Silencer
15. Diaphragm
Retainer
16. Primary Diaphragm
F5823
17. Primary Support Plate
18. Secondary Piston Bearing
19. Housing Divider
20. Secondary Diaphragm
21. Secondary Support Plate
41. Power Piston Assembly
Figure 27—Power Piston Group
7. Reaction piston (23) and reaction disc (22) into the
reaction body (25).
8. Reaction body (25).
9. Reaction body retainer (24).
• Lubricate the inside diameter of the secondary dia­
phragm (20) lip, inside diameter of the primary dia­
phragm (16) lip and the secondary piston bearing
(18) with a thin layer of silicone grease.
10. Secondary diaphragm (20) into the secondary sup­
port plate (21).
11. Secondary diaphragm (20) and support plate (21)
over the power piston assembly (41) (figure 28).
• Use J 28458 as a guide to protect the power
piston.
12. Secondary piston bearing (18) into the housing
divider (19) with the flat surface of the bearing on
the same side as the six raised lugs on the divider.
13. Secondary piston bearing (18) and housing divider
(19) over the power piston assembly (41). Use
J 28458 as a guide (figure 29).
14. Primary diaphragm (16) into the primary support
plate (17).
BRAKES 5-13
F5893