Pontiac Fiero 1988 Service Manual page 263

5D2-2 POWER HEAD ASSEMBLY
GENERAL DESCRIPTION
This booster is a tandem vacuum suspended unit,
in a normal operating mode, with the service brakes in
the released position, the tandem vacuum suspended
booster operates with vacuum on both sides of its
diaphragms. When the brakes are applied, air at
atmospheric pressure is admitted to one side of each
diaphragm to provide the power assist. When the
service brake is released, the atmospheric air is shut off
from the one side of each diaphragm. The air is then
drawn from the booster through the vacuum check
valve to the vacuum source.
Important
m Replace all components included in repair kits
used to service this booster,
o Lubricate rubber parts with silicone grease,
provided in kits, to ease assembly.
® Do not use lubricated shop air on brake parts as
damage to rubber parts may result,
o If any hydraulic component is removed or
disconnected, it may be necessary to bleed all or
part of the brake system,
o The torque values specified are for dry,
unlubricated fasteners.
© Perform service operations on a clean bench free
from all mineral oil materials.
ON-CAR SERVICE
BOOSTER ASSEMBLY
(Figure 2)
4HM Remove or Disconnect
-•4-
Install or Connect
1. Master cylinder attaching nuts (37).
2. Master cylinder (34) from booster (35).
3. Booster pushrod (32) from brake pedal.
4. Booster attaching nuts (36) and booster (35).
See NOTICE
on page
5-1
34 \ >
v
32. PUSHROD
34. MASTER CYLINDER
35. BOOSTER
36. NUT 35
37. NUT
HM0002-5D2-AB
Figure 2 Removing Booster Assembly
1. Booster (35) and attaching nuts (36) to 21 N
-
m
(15 lb-ft).
2. Booster pushrod (32) to brake pedal.
3. Master cylinder (34) to booster (35) and
attaching nuts (37) to 27 N-m (20 lb-ft).
EXTERIOR COMPONENTS
(Figure 3)
jTj Important
1.
2.
3.
4.
The vacuum check valve, grommet and front
housing seal can be inspected and/or serviced without
removing the booster from the vehicle.
|«--»| Remove or Disconnect
Booster (35) as previously described.
Boot (1) and silencer (2).
Vacuum check valve (3) and grommet (4).
Front housing seal (7).
Inspect
Boot, front housing seal, and grommets for:
• Cuts
• Nicks
• Excessive wear
Replace part(s) if any of the above are found.
Clean
• Above parts in clean denatured alcohol.
# Dry with unlubricated compressed air.
See NOTICE on page 5-7.
Install or Connect
m Lubricate inside and outside diameters of grommet
(4) and front housing seal (7) with a thin layer of
silicone grease.
1. Grommet (4) and vacuum check valve (3).
2. Front housing seal (7).
3. Silencer (2) and boot (1).
4 Booster (35) as previously described.
UNIT REPAIR
BOOSTER
Tool Required:
J 23456 Power Brake Booster Disassembly
and Reassembly Tool
(Figures 4 thru 6)
Disassemble
1. Booster (35) as previously described.
2. Scribe a mark on front and rear housings (10 and
9) to aid reassembly.
3. Using Tool J 23456 (39), apply force' in a
counter-clockwise direction to unlock housings (9
and 10).
4. Return spring (11) and power piston group (38).