1988 PONTIAC FIERO Service Repair Manual

5C3-2 DIRECT TORQUE DRUM BRAKE ASSEMBLY
GENERAL DESCRIPTION
This drum brake asembly is a duo-servo, direct
torque design. In the duo-servo brake, the force which
the wheel cylinder applies to the primary shoe is
multiplied by the primary lining friction to provide a
very large force applied to the secondary shoe. With
the direct torque design, torque from the brake shoes
is transferred directly through the anchor pin to the
axle flange. Adjustment for both the primary and
secondary shoe and linings is automatic during reverse
brake applications.
Important
a Replace all components included in repair kits
used to service this drum brake.
a Lubricate parts as specified.
e Do not use lubricated shop air on brake parts as
damage to rubber components may result.
a If any hydraulic components is removed or
disconnected, it will be necessary to bleed all or
part of the brake system.
s Replace shoe and linings in axle sets only.
e The torque values specified are for dry,
unlubricated fasteners.
e Perform service operations on a clean bench free
from all mineral oil materials.
CAUTION: When servicing brake
parts, do not create dust by grinding or
sanding brake linings or by cleaning
wheel brake parts with a dry brush or
with compressed air.
A water
dampened cloth should be used.
Many
brake parts contain asbestos fibers
which can become airborne if dust is
created during servicing. Breathing
dust containing asbestos fibers may
cause serious bodily harm.
ON-CAR SERVICE
BRAKE COMPONENTS
Tool Required:
J 8049 Brake Spring Remover and Installer
J 8057 Brake Spring Pliers
J 29839 Brake Cylinder Retainer Remover
See Figures 2,3 and 4
Remove or Disconnect
1.
Raise car and suitably support, see Section OA.
e Mark relationship of wheel to axle flange.
2. Wheel and tire.
e Mark relationship of drum to axle flange.
3. Brake drum.
a If dificulty is encountered in removing
drum the following steps may be of
assistance:
@ Make sure parking brake is released.
a Back off parking brake cable
adjustment.
a Remove adjusting hole cover or
knockout plate from backing plate and
back off adjusting screw using screw
driver and adjusting tool.
a Use a rubber mallet to tap gently on
outer rim of the drum and/or around
inner drum diameter by spindle. Take
car not to deform by excessive use of
force.
4. Return springs (1 and 2) using
J 8049 pliers.
5. Hold-down springs (3) and pins (5) using suitable
pliers.
6. Lever pivot (4).
7. Actuator link (6) while lifting up on actuator
lever
(7).
8. Actuator lever (7) and lever return spring (8).
9.
Shoe guide (9), parking brake strut (10) and strut
spring
(1 1).
10. Shoe and lining assemblies (12 and 13) after
disconnecting parking brake cable.
11. Adjusting screw assembly (29) and spring (14).
12. Parking brake lever (18) by unhooking lever tab
from secondary shoe (13) slot.
e If any parts are of doubtful strength or quality
due to discoloration from heat, over-stress, or are
worn, the parts should be replaced.

DIRECT TORQUE DRUM BRAKE ASSEMBLY 5C3-3
1. RETURN SPRING 6. ACTUATOR LINK 11. STRUT SPRING 26. BACKING PLATE 2. RETURN SPRING 7. ACTUATOR LEVER 12. PRIMARY SHOE 27. ANCHOR PIN 3. HOLD-DOWN SPRING 8. LEVER RETURN SPRING 13. SECONDARY SHOE 29. ADJUSTING SCREW ASSEMBLY 4. LEVER PIVOT 9. SHOE GUIDE 14. ADJUSTING SCREW SPRING 37 SHOE PADS (6 PLACES) 5. HOLD-DOWN PIN 10. PARKING BRAKE STRUT 18. PARKING BRAKE LEVER
Figure 2 Brake Components
Install or Connect
e See NOTICE on page 5-1.
1. Parking brake lever (18) on secondary shoe (12)
by hooking lever tab into secondary shoe (13).
o Threads of adjusting screw (17) for smooth
rotation over full length.
Clean
e Before reinstalling, adjusting screw asse~nbly (29)
must be disassembled and thoroughly cleaned and
lubricated.
@ Clean adjuster screw ( 17) threads with a wire
brush.
@ Wash all components in denatured alcohol.
o Apply brake lubricant P/N 5450032 or
equivalent to the adjusting screw (17)
threads, inside diameter of socket (15) and
socket face.
e Adequate lubrication is achieved when a
continuous bead of lubricant is at open end
of pivot nut (16) and socket (15) when
threads are fully engaged.
2. Adjusting screw assembly (29) and spring
(14).
3. Shoe and lining assemblies (12 and 13) after
attaching parking brake cable. For cable
adjustment see
PARKING BRAKE
ADJUSTMENT.
4. Parking brake strut (10) and strut spring
(1 1) by
spreading shoes (12 and 13) apart. To be properly
positioned.
o The end without the spring (11) should
engage the parking brake lever (18) and
shoe lining (12 and 13).
e~ The end with the spring should engage the
opposite shoe and lining (12 or 13).
5. Shoe guide
(9), actuator lever (7) and lever return
spring
(8).
6. Hold-down pins (5), lever pivot (4) and
hold-down springs (3).
7. Actuator link (6) on anchor pin (27).

8. Actuator link (6) into actuator lever (7) while
holding up on lever.
9. Shoe return springs (1 and 2) using J 8057 pliers.
10. Brake drum.
1 1. Wheels and tires.
Lower car.
Torque wheel nuts. See Section 3E
WHEELS AND TIRES.
BRAKE ADJUSTMENT
See Figure 5
1. Raise car and suitably support.
Mark relationship of wheel to axle flange.
2. Wheel and tire.
o Mark relationship of drum to axle flange.
3. Measure drum inside diameter (ID) using J
21 177-A.
4. Turning star wheel, adjust shoe and lining
diameter to be 1.27 mm (0.050 in) less than inside
drum diameter for each rear wheel.
5. Install drums and wheels, aligning previous
marks.
s Torque wheel nuts. See Section 3E
WHEELS AND TIRES.
6. Make several alternate forward and reverse stops
applying firm force to the brake pedal. Repeat
until ample pedal reserve is built up.
TO RETRACT BRAKE SHOES
STAR WHEEL ROTATION
TO
EXPAND BRAKE SHOES
PARKING BRAKE ADJUSTMENT
Adjustment of parking brake cable is necessary
whenever the rear brake cables have been disconnected.
Need for parking brake adjustment is indicated if the
hydraulic brake system operates with good reserve, but
the parking brake hand level travel is less than 13 ratchet
clicks or more than 17 ratchet clicks.
1. Pull parking brake hand lever exactly two ratchet
clicks.
2. Raise and suitably support car.
important
To prevent damage to the threaded parking brake
adjusting rod when servicing the parking brake,
the following is recommended.
@ Before attempting to turn the adjusting nut,
clean the exposed threads on each side of the
nut.
@ Lubricate the threads of the adjusting rod be-
fore turning the nut.
Figure 3 Backing Off Adjusting Screw 3. Tighten adjusting nut until the left rear wheel can
just be turned rearward using two hands but is
PROPER SPRING 'LUBRICATE WITH THIN COATING OF 5450032 LUBRICANT (OR EQUIVALENT)
29
12. PRIMARY SHOE 13. SECONDARY SHOE 14. ADJUSTING SCREW SPRING 15. SOCKET 16. PIVOT NUT 17. ADJUSTING SCREW 29. ADJUSTING SCREW ASSEMBLY
Figure 4 Adjusting Screw Assembly

DIRECT TORQUE DRUM BRAKE ASSEMBLY 5C3-5
A. SETTING TOOL TO DRUM B. SETTING BRAKE
SHOES TO TOOL
Figure 5 Measuring Drum and Shoe for Adjustment
locked when forward rotation is attempted.
4. With mechanism totally disengaged, rear wheels
should turn freely in either direction with no brake
drag. It is very important that parking brake cables are
not adjusted too tightly causing brake drag.
5. Remove support and lower car.
WHEEL CYLINDER
See Figures 6 thru 9
Clean
s Dirt and foreign material around wheel cylinder
assembly
(28) inlet and pilot.
Remove or Disconnect
1. Inlet tube nut and line.
Plug opening in line to prevent fluid loss
and contamination.
2. Wheel cylinder retainer (19) using J 29839
Retainer Remover or two awls.
s Insert awls (30) into access slots between
wheel cylinder
(28) pilot and retainer (19)
locking tabs.
s Bend both tabs away simultaneously.
3. Wheel cylinder (28).
19. WHEEL CYLINDER RETAINER 28. WHEEL CYLINDER
Figure 6 Wheel Cylinder

5C3-6 DIRECT TORQUE DRUM BRAKE ASSEMBLY
19. WHEEL CYLINDER RETAINER
30. AWL
Figure 7 Removing Wheel Cylinder Retainer
31. SOCKET EXTENSION 32. 1-118 IN., 12 PT. SOCKET
1 HM0007-5C3-FG Figure 9 Installing Wheel Cylinder Retainer
Figure 8 Removing Wheel Cylinder with
J 29839

DIRECT TORQUE DRUM BRAKE ASSEMBLY 5C3-7
Install or Connect
See NOTICE on page 5- 1.
1. Position wheel cylinder assembly (28) and hold in
place with wooden block between cylinder and
axle flange.
2. New retainer (19) over wheel cylinder abutement
using a 1-
1/8 inch 12-point socket (32) and socket
extention (31) as shown in figure
6.
3. Inlet tube nut to 17 N-m (13 1b-ft).
4. Bleed wheel cylinder.
BACKING PLATE
Remove or Disconnect
1. Raise
car and suitably support, see Section OA.
2. Brake
components as previously described.
3. Axle shaft, see Section 4B.
4. Parking brake
cable from backing plate
5. Brake pipe from wheel cylinder
6. Backing plate bolts and nuts
7. Anchor
pin nut and anchor pin
Install or Connect
1. Backing plate to axle flange
2. Backing plate to axle flange nuts and bolts to 58
N.m (45 lbs. ft.)
3. Anchor
in and nut to 140 N.m ( 103 Ibs. ft.)
4. Brake
pipe to
wheel cylinder to 15 N.nl (I l Ibs.
ft.)
5. Parking brake cable to backing plate
6. Axle shaft, see section 48
7. Brake
components as previously described
8. Lower car.
9. Bleed brake hydraulic syatcm
10. Adjust brake asscnlbly and parking brakc
UNIT REPAIR
WHEEL
CYLINDER OVERHAUL
See Figure 10
+++ Disassemble [I]
1. Wheel cylinder completely from vehicle as
previously described.
2. Boots (20).
3. Pistons (21) and seals (22).
4. Spring assembly (23).
5. Bleeder valve (24).
e Cylinder bore for:
e Scoring
e Nicks
e Corrosion
e Wear
e Use crocus cloth to polish out light corrosion.
e Replace wheel cylinder assembly if bore will not
clean up with crocus cloth.
e Pistons for:
e Scoring
e Nicks
e Corrosion
e Wear
22 SEAL 23 SPRING ASSEMBLY 24 BLEEDER VALVE 25 CYLINDER BODY
Figure 10 Wheel Cylinder Components
Clean
e All parts in clean denatured alcohol.
e Dry with unlubricated compressed air.
e Lubricate new seals with clean brake fluid.
Assemble
e See NOTICE on page 5-1.
1. Bleeder valve (24) to 6 N.m (50 lb-in).
2. Spring assembly (23).
3. Seal
(22), pistons (21) and boots (20).
4. Wheel
cylinder as previously described,

POWER HEAD ASSEMBLY 582-1
SECTION 582
POWER HEAD ASSEMBLY - TANDEM
APHRAGM
CONTENTS
...................... GENERAL DESCRIPTION 5D2-2 Unlocking and Locking Booster ................ 5D2-3
................................. ON-CAR SERVICE 5D2-2 Power Piston Group ................................. 5D2-3
..................................... Booster Assembly 5D2-2 Power Piston Disassembly ......................... 5D2-4
................................. Exterior Components 5D2-2 Gaging Procedure ...................................... 5D2-7
......................................... UNIT REPAIR 5D2-2
I 1. BOOT I 2. SILENCER 3. VACUUM CHECK
VALVE
4. GROMMET 5. VACUUM SWITCH
(SOME MODELS)
6. GROMMET 7. FRONT HOUSING SEAL 8. PRIMARY PISTON
BEARING
9. REAR HOUSING 10. FRONT HOUSING 11. RETURN SPRING 12. PISTON ROD (GAGED)
13. REACTION
RETAINER
14. POWER HEAD
SILENCER
15. DIAPHRAGM
RETAINER
16. PRIMARY
DIAPHRAGM
17. PRIMARY SUPPORT
PLATE
18. SECONDARY PISTON
BEARING
19. HOUSING DIVIDER 20. SECONDARY
DIAPHRAGM
21. SECONDARY
SUPPORT PLATE
22. REACTION DISC 23. REACTION PISTON 24. REACTION BODY
RETAINER
25. REACTION BODY 26. AIR VALVE SPRING 27. REACTION BUMPER 28. RETAINING RING 29. FILTER 30. RETAINER 31. O-RING 32. AIR VALVE PUSH
ROD ASSEMBLY
33. POWER PISTON
Figure 1 Booster Assembly