1988 PONTIAC FIERO Service Repair Manual

5-12 BRAKES
27 27.m (20 FT. LBS.) BOLTISCREW
1 18 18.m (13 FT. LBS.)
Figure 1 1 Rear Brake Hose and Pipes
6. Wheel and tire. See Section 3E.
Center Brake Hose (Figures 10 and 11)
0 Dirt and foreign material from hose and fittings.
Remove or Disconnect
1. Front brake pipe from brake hose at hose mounting
bracket.
* Use a backup wrench on hose fitting.
0 Be careful not to bend bracket or pipe.
2. Spring clip on hose mounting bracket.
3. Hose from mounting bracket.
4. Two rear brake pipes from junction block. 0 Be careful not to bend pipes.
5. Bolt and junction block from rear axle.
Note position of junction block for proper loca-
tion during installation.
* Bolt to 27 N.m (20 Ibs. ft,).
0 Brake pipes to 15 N.m (1 1 Ibs. ft.).
3. Hose in mounting bracket.
Hose will only fit in bracket in one position. Be
sure hose is seated properly and not twisted.
4. Spring clip on hose mounting bracket.
5. Front brake pipe to hose at hose mounting bracket.
Tighten
0 Brake pipe to 15 N.m (1 1 Ibs. ft.).
Rear Disc Brake Hose
Remove or Disconnect (Figure
11)
1. Wheel and tire. See Section 3E.
Install or Connect (Figures 10 and 11) 0 Dirt and foreign material from hoses and fit-
tings.
NOTICE: See "Notice" on page
5-1 for steps 1 2. Brake pipe from brake hose at hose mounting
and
5. bracket. Use a backup wrench on hose fitting.
1. Two brake pipes into junction block. Be
careful not to bend bracket or pipe.
2. Junction block and bolt to rear axle. 3. Spring clip at hose mounting bracket.

BRAKES 5-13
4. Bolt, hose and two copper gaskets from caliper.
Discard two copper gaskets.
Install or Connect (Figure 1 1)
NOTICE: See "Notice" on page 5-1 for steps 1
and 4.
1. Bolt, hose, and two copper gaskets to caliper.
0 Use new copper gaskets. 0 Lubricate bolt threads with brake fluid.
0 Bolt to 44 N.m (32 Ibs. ft.).
2. Hose into bracket. r There should be no kinks in hose.
3. Spring clip at hose mounting bracket.
4. Brake pipe to brake hose.
Use backup wrench on hose fitting.
0 Be careful not to bend bracket or pipe.
Tighten
Fittings to 15 N.m (1 1 Ibs. ft.).
5. Bleed brake system. See "Bleeding Brake Hydraulic
System" in this section.
6. Wheel and tire. See Sectbn 3E.
PARKING BRAKE
This vehicle is equipped with coated parking brake cable
assemblies. The wire strand is coated with a plastic mate- rial which slides over plastic seals inside
the conduit end
fittings. This is for corrosion protection and reduced park-
ing brake effort.
NOTICE: Handling of these cables during servic-
ing of the parking brake system requires extra care.
Damage to the plastic coating will reduce corrosion
protection and if the damaged area passes through
the seal, increase parking brake effort could result.
Contact of the coating with sharp-edged tools, or
with sharp surfaces of the vehicle underbody,
shou be avoided.
To prevent damage to the threaded parking brake adjust-
ing rod when servicing the parking brake, the following is
recommended:
r Before attempting to turn the adjusting nut, clean the
exposed threads on each side of the nut.
Lubricate the threads of the adjusting rod before turn-
ing the nut.
PARKlNG BRAKE CONTROL ASSEMBLY
Remove or Disconnect (Figure 12)
Raise vehicle. See Section OA.
@ Loosen adjusting nut at equalizer enough to allow
cable to be disconnected from parking brake control
assembly. Lower vehicle. See Section OA.
1. Carpet finish molding.
2 N-m (18 LBS. IN.)
a PARK BRAKE LEVER
BRACKET (LEVER)
CABLE ASSEMBLY
Figure 12 Parking Brake Control Assembly

2. Console. Refer to INSTRUMENT PANEL, GAGES
AND CONSOLE (SEC.
8C).
3. Wiring from switch.
4. Cable and casing from control assembly. * Use a lh-inch box end wrench to free casing
from control assembly.
5. Two bolts and control assembly from floor pan.
Install or Connect (Figure 12)
1. Two bolts and control assembly to floor pan.
Two bolts to 10
N.m (7 Ibs. ft.).
2. Cable and casing to control assembly.
3. Wiring to switch.
4. Console. Refer to INSTRUMENT PANEL, GAGES
AND CONSOLE (SEC.
8C).
5. Carpet finish molding.
@ Parking brake. See Section 566 or 5C3.
PARKING BRAKE CABLES
Parking Brake Front Cable
Remove or Disconnect (Figure 12)
@ Raise vehicle. See Section OA.
1. Adjusting nut from equalizer.
2. Spring retainer clip from bracket. * Lower vehicle. See Section OA.
3. Upper console cover and lower console rear screws.
@ Lift rear of lower console for access to cable retainer
at hand lever.
4. Cable retainer pin, cable retainer and cable.
Install or Connect (Figure 12)
1. Cable, cable retainer and cable retainer pin.
2. Lower console rear screws and upper console cover.
Raise vehicle. See Section OA.
3. Spring retainer clip to bracket.
4. Adjusting nut to equalizer.
Lower vehicle. See Section OA.
Adjust
Parking brake. See Section 586 or 5C3.
Parking Brake Rear Cable (Drum Brakes)
Remove or Disconnect (Figures 12 and
13)
* Raise vehicle. See Section OA.
1. Rear cable at connector.
Loosen adjusting nut at equalizer.
2. Wheel and brake drum. * Mark relationship of wheel to axle flange.
3. Cable at brake shoe operating lever.
* Bend retainer fingers.
Lower vehicle. See Section OA.
Figure
13 Rear Parking Brake Cables

BRAKES 5-15
lnspect rear drum brake shoe and lining assemblies.
Install or Connect (Figures 12 and 13)
When the thickness of any lining is worn within 0.76 mm
Raise vehicle. See Section OA. (0.030-inch)
of the shoe or rivet, the shoe and lining
1. Cable at brake shoe operating lever. assemblies must
be replaced. Replace shoe and lining
Bend retainer fingers. assemblies
in axle sets.
2. Brake drum and wheel.
3. Rear cable at connector.
0 Lower vehicle. See Section oA. INSPECTING AND REFINISHING ROTORS
Adjust
0 Parking brake. See Section 5C3.
Parking Brake Rear Cable (Disc Brakes)
Remove or Disconnect (Figures
12 and 13)
0 Raise vehicle. See Section OA.
1. Rear cable from connector.
0 Loosen adjusting nut at equalizer.
2. Cable from brake caliper.
Push forward on caliper parking brake apply
lever.
@ Remove cable from tang in lever.
Release lever.
Lower vehicle. See Section OA.
Install or Connect (Figures 12 and
13)
Raise vehicle. See Section OA.
1. Cable to brake caliper.
0 Push forward on caliper parking brake apply
lever.
0 Install cable in lever tang.
Release lever.
2. Rear cable to connector. 0 Lower vehicle. See Section OA.
0 Parking brake. See Section 586.
BRAKE LINING INSPECTION
(Figure 14)
lnspect the brake linings at least twice a year when the
wheels are removed (tire rotation, etc.). Check both ends of
the outer shoe by looking in at each end of the caliper.
These are the points at which the highest rate of wear nor-
mally occurs. Also, check the lining thickness of the inner
shoe to make sure that it has not worn prematurely. Look
through the hole in the top of the caliper to view the inner
shoe. When the thickness of any lining is worn to within
0.76
mm (0.030-inch) of the shoe or rivet, all disc brake
shoes and linings should be replaced in axle sets.
All disc brakes have a wear indicator that makes a noise
when the linings wear to a degree where replacement is
required. The wear indicator is an integral part of the shoe
and lining. When the lining is worn, the clip indicator con-
tacts the rotor and produces a warning noise.
Check flatness of brake linings. Place inner shoe lining
and outer shoe lining surfaces together and check for gap
between surfaces. If more than 0.13 mm
(.OO&inch) gap is
measured midway between attaching lugs, shoe and lining
assembly must be replaced. Thickness
Variation Check
Thickness variation can be checked by measuring the
thickness of the rotor at four or more points around the
circumference of the rotor. All measu'rements must be
made at the same distance in from the edge of the rotor. A
rotor that varies by more than
.013 mm (.0005-inch) can
cause pedal pulsation
and/or front end vibration during
brake applications. A rotor that does not meet these specifi-
cations should be refinished to specifications or replaced.
Lateral
Wunout Check (Figure 15)
1. Tighten wheel bearings until all the play is out of the
bearings. See Section 3C.
2. Remove caliper.
3. Fasten a dial indicator to the steering knuckle so that
the indicator button contacts the rotor about
25 mm (1
inch) from the rotor edge.
4. Zero the dial indicator.
5. Move the rotor one complete revolution, and observe
total indicated
runout (T.I.R.).
6. Readjust wheel bearings. See Section 3C.
Figure 14 Lining Inspection

5-16 BRAKES
Figure 15 Checking Lateral Runout
Lateral runout of the rotor should not be over 0.13 mm
(0.005-inch). A rotor that does not meet the lateral runout
specification should be resurfaced or replaced.
Rotor Tolerance and Surface Finish
In manufacturing the brake rotor, tolerances of the brak-
ing surfaces for flatness, thickness variation and lateral
runout are held very close. The maintenance of close toler-
ances on the shape of the braking surfaces is necessary to
prevent brake roughness. In addition to these tolerances, the surface finish must be
held to a specified range. The control of the braking surface
finish is necessary to avoid pulls and erratic performance
and to extend lining life.
Light scoring of the rotor surfaces not exceeding
0.38
mrn (0.015-inch) in depth, which may result from nor-
mal use, will not affect brake operation.
Refinishing Brake Rotors
All brake rotors have a minimum thickness dimension
cast into them. This dimension is the minimum wear dimen-
sion and not a refinish dimension. Do not use a brake rotor
that will not meet specifications. See Section
5F.
Since accurate control of the rotor tolerances is neces-
sary for proper performance of the disc brakes, machining
of the rotor should be done only with precision equipment.
When refinishing rotors, always use sharp cutting tools
or bits. Dull or worn tools leave a poor surface finish which
will affect initial braking performance. Vibration dampening
attachments should always be used when refinishing brak-
ing surfaces. These attachments eliminate tool chatter and
will result in better surface finish.
The optimum speed for refinishing braking surfaces is a
spindle speed of 200 rpm. Crossfeed for rough cutting
should range from 0.254-0.152 mm (0.010-0.006-inch) per
revolution. Finish cuts should be made at crossfeeds no
greater than 0.051 mm (0.002-inch) per revolution.
INSPECTING AND REFlNlSHlMG BRAKE
DRUMS
Whenever brake drums are removed, they should be
thoroughly cleaned and inspected for cracks, scores, deep
grooves, out-of-round and tapered conditions.
Cracked, Scored, or Grooved Drum
A cracked drum is unsafe for further service and must be
replaced. Do not attempt to weld a cracked drum.
Smooth any slight scores. Heavy or extensive scoring will
cause excessive brake lining wear, and it may be neces-
sary to resurface the brake drum to true up the braking
surface.
If the brake linings are slightly worn and the drum is
grooved, the drum should be polished with fine emery
cloth. The brake drums should not be turned since eliminat-
ing all the grooves in the drum and smoothing the ridges on
the lining would remove too much metal and lining. If left
alone, the grooves and ridges match and satisfactory serv-
ice can be obtained. If brake linings are replaced, a grooved drum should be
turned. Agrooved drum, if used with new lining, will not only
wear the lining, but will make it difficult, if not impossible, to
obtain efficient brake performance.
But-Of-Round or Tapered Drum
An out-of-round or tapered brake drum makes accurate
brake shoe adjustment impossible and will cause exces-
sive wear of other parts of the brake mechanism. An out-of-
round drum can also cause severely irregular tire tread
wear as well as a pulsating brake pedal. When the braking
surface of a brake drum exceeds the specification limits,
the drum should be turned to true up the braking surface.
Out-of-round, taper and brake drum wear can be accurately
measured with an inside micrometer fitted with proper
extension rods. When measuring a drum for out-of-round, taper and
wear, take measurements at the open and closed edges of
braking surface and at right angles to the edges.
Refinishing Brake Drums
If adrum is to be refinished, remove only enough metal to
obtain a true, smooth braking surface. If a drum does not
meet specifications when turned to the maximum
rebore
diameter shown in the specifications, shown in Section 5F,
it must be replaced. Removal of more metal will affect dissi-
pation of heat and may cause distortion of the drum.
All brake drums have a maximum diameter cast into
them. This diameter is the maximum wear diameter and not
a refinish diameter. Do not refinish a brake drum that will
not meet the specifications. Refer to specification chart,
Section 5F. When refinishing drums, always use sharp cutting tools
or bits. Dull or worn tools leave a poor surface finish which
will affect braking performance. Vibration dampening
attachments should always be used when refinishing brak-
ing surfaces. These attachments eliminate tool chatter and
will result in better surface finish.
Brake Drum Balance
During manufacture, weights are used to balance brake
drums. These weights must not be removed.
After drums are refinished or if difficulty is experienced in

BRAKES 5-17
maintaining proper wheel balance, brake drums should be
checked for balance. Brake drums may be checked for
balance on most off-the-car balancers.
COMBINATION VALVE
Testing Combination Valve Electrical Circuit
When removing the electrical wire connector from the
pressure differential switch, squeeze the
eliptical shaped
plastic locking ring and pull up. This will move the locking
tangs away from the switch. Pliers can be used to help
remove the connector.
1. Disconnect wire from switch terminal and use a
jumper to connect wire to a good ground.
2. Turn ignition key to "ON." The warning lamp should
light. If lamp does not light, bulb is burned out or
electrical circuit is faulty. Replace bulb or repair elec-
trical circuit as necessary.
3. When warning lamp lights, turn off ignition switch.
Disconnect jumper and connect wire to switch termi-
nal.
Testing Combination Valve Warning Lamp Switch
1. Attach a bleeder hose to a rear brake bleed screw and
immerse the other end of the hose in a container
partially filled with clean brake fluid. Be sure master
cylinder reservoirs are full.
2. Turn ignition switch to "ON." Open bleeder screw
while an assistant applies moderate pressure to the
brake pedal. Warning lamp should light. Close
bleeder screw before assistant releases brake pedal.
Apply brake pedal with moderate-to-heavy pressure.
Lamp should go out.
3. Attach the bleeder hose to a front brake bleeder
screw and repeat steps
1 and 2. Warning lamp action
should be the same as in step
2. Turn off ignition
switch.
4. If warning lamp does not light during steps 2 and 3,
but does light when a jumper is connected to ground,
the warning lamp switch portion of the combination
valve is faulty. Do not disassemble the combination
valve.
If any portion of the combination valve is faulty,
it must be replaced with a new combination valve.
Combination Valve Replacement
Remove or Disconnect (Figure
16)
r The combination valve is not repairable and must be
serviced as a complete assembly.
1. Hydraulic pipes at combination valve.
Plug pipes to prevent loss of fluid and entrance
of dirt.
2. Wiring harness from valve switch terminal.
3. Nut attaching valve to power booster.
4. Combination valve.
@ Install or Connect (Figure 16)
NOTICE: See "Notice" on page 5-1.
1. Combination valve.
2. Nut attaching valve to power booster.
Tighten
* Nut to 24 N.m (18 Ibs. ft.).
3. Wiring harness to valve switch terminal.
4. Hydraulic pipes at combination valve. * Bleed brakes. See "Bleeding Brake Hydraulic Sys-
tem" in this section.
CAUTION: Do not move the car until a firm brake
pedal is obtained. Air in the brake system can
cause loss of brakes.
POWER BRAKE VACUUM HOSE FILTER
See Figure 17.
COMBINATION VALVE ASM.
MASTER CYLINDER BRAKE PIPES
Figure 16 Combination Valve
2 FILTER 4. BOOSTER
Figure 17 Power Brake Vacuum Hose Filter (Typical)

COMPOSITE MASTER CYLINDER 5A3-1
SECTION 5A3
COMPOS TE MASTER CYL
CONTENTS
GENERAL DESCRIPTION .............................................................................................. 5A3-2
ON-CAR SERVICE ..................... .. ............................................................................... 5A3-2
Master Cylinder Assembly ..................... .. ..................................................................... 5A3-2
................... UNIT REPAIR ....... .............................................................................. 5A3-2
Master Cylinder Overhaul ............................................................................................... 5A3-2
Master Cylinder Reservoir ................................... .... .......................................................... 5A3-3
1. RESERVOIR COVER 2. RESERVOIR
DIAPHRAGM
3. RESERVOIR 4. RESERVOIR
GROMMET
5. LOCK RING 6. PRIMARY PISTON
ASSEMBLY
7. SECONDARY SEAL 8. SPRING RETAINER 9. PRIMARY SEAL 10. SECONDARY PISTON 11. SPRING 12. CYLINDER BODY
QUICK TAKE-UP VALVE
(NOT SERVICEABLE)
Figure 5A3-1 Composite Master Cylinder