1988 PONTIAC FIERO warning

REAR AXLE 48-13
2. Drive
pinion oil seal from carrier and remove
front pinion bearing. If the bearing is to be
replaced, remove outer race from carrier.
3. If rear pinion bearing is to be replaced remove
outer race from carrier using a punch in slots
provided for this purpose.
1 -REMOVER J-22912-01 7%" OR J-33868
2-OPENING IN TOOL MUST BE SUPPORTED
Fig.
604 Removing Rear Pinion Bearing
Cleaning and Inspecting
1. Clean
all rear axle bearings thoroughly in clean
solvent (do not use a brush). Examine bearings
visually and by feel. All bearings should feel
smooth when oiled and rotated while applying as
much hand pressure as possible. Minute scratches
and pits that appear on rollers and races at low
mileage are due to the initial pre-load, and
bearings having these marks should not be
rejected.
2. Examine sealing surface of pinion flange for nicks
burrs, or rough tool marks which would cause
damage to the seal and result in an oil leak.
Replace if damaged.
'
3. Examine carrier bore and remove any burrs that
might cause leaks around the O.D. of the pinion
seal.
4. Examine the ring gear and drive pinion teeth for
excessive wear and scoring. If any of these
conditions exist replacement of the gear set will
bs required.
5. Inspect the pinion gear shaft for unusual wear;
also check the pinion and side gears and thrust
washers.
6. Check the press fit of the side bearing inner race
on the rear axle case hub by prying against the
shoulder at the puller recess in the case. Side
bearings must be a tight press fit on the hub.
7. Diagnosis of a rear axle failure such as: chipped
bearings, loose (lapped-in) bearings, chipped
gears, etc., is a warning that some foreign
material is present; therefore the axle housing
must be cleaned.
Drive Pinion
Assemble
I. If a new rear pinion bearing is to be installed,
install new outer race.
2. If a new front pinion bearing is to be installed,
install new outer race.
Fig. 605 Installing Rear Pinion Bearing Outer Race
1- J-8092 DRIVE H-,.wb- 6
Fig. 606 Installing Front Pinion Bearing Outer Race
Setting Drive Pinion Depth
Pinion depth is set with pinion setting gage
J 21777-B. The pinion setting gage provides in effect a
"Nominal" or "Zero" pinion as a gaging reference.
Set up pinion setting gage as follows:
1. Make certain all gage parts are clean.
2. Lubricate front and rear pinion bearings which
will be used in final reassembly and position them
in their respective races in the carrier. Bearings
used with gage set must be those to be installed
in vehicle, in order to insure accurate reading.
3. Assemble pinion setting gage assembly into
carrier housing as follows:
Step 1
Figure 607
a.
Install Pinion Bearing Pre-Load Stud J
21777-43 through Pilot J 23597-12 and into
Gage Plate
J 23597- 11.
b. Install stud and plate assembly into housing
and install Front Pinion Bearing Pilot
J
21777-42 and hex nut over end of stud,
tightening nut until snug and rotate gage

BRAKES
NOTICE: All brake attaching fasteners are important attaching parts in that they could affect the performance of vital parts
and systems.
andlor could result in major repair expense . They must be replaced with one of the same part number or with an
equivalent part if replacement becomes necessary
. Do not use a replacement part of lesser quality or substitute design .
Torque values must be used as specified during reassembly to assure proper retention of parts .
CAUTION: When servicing brake parts. do not create dust by grinding. sanding brake linings. or by cleaning brake
parts with a dry brush or with compressed air
. 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 . A water
dampened cloth or water based solution should be used to remove any dust on brake parts
. Equipment is commer-
cially available to perform this washing function
. These wet methods will prevent asbestos fibers from becoming
airborne
.
CONTENTS
......................... General Description 5.2
Composite Master Cylinder
.................. 5.2
Brake Fluid Level
lndicatgr ................... 5.2
Operation of Disc Brake
..................... 5.2
Operation of Drum Brake
.................... 5.2
Operation of Combination Valve
............... 5.2
Brake Pressure Differential
.......................... Warning Switch 5.2
Diagnosis and Inspection ..................... 5.3
Brake System Testing
....................... 5.3
External Conditions That Affect Brake Performance
.................... -5-3
Warning Lamp Operation .................... 5.3
Brake Fluid Leaks
.......................... 5.3
Master Cylinder Check
...................... 5.3
Substandard or Contaminated
BrakeFluid ............................. 5-3
............................. On-Car Service 5.7
Brake Pedal Replacement
................... 5.7
Stoplamp Switch Adjustment ................. 5-7
Filling Master Cylinder Reservoirs
............. 5-7
Bleeding Brake Hydraulic System
............. 5.7
Manual Bleeding
......................... 5.8
Pressure Bleeding
........................ 5.8
Flushing Brake Hydraulic System
............. 5.9
Brake Pipe Replacement
.................... 5.9
............................. I.S.O. Flare 5.9
Brake Hose Inspection
...................... 5.9
Brake Hose Replacement
.................... 5.11
Front Brake Hose
........................ 5.11
....................... Center Brake Hose 5.12
..................... Rear Disc Brake Hose 5.12
ParkingBrake ............................. 5-13
Parking Brake Control Assembly
.............. 5.13 Parking Brake Cables
....................... 5.14
Parking Brake Front Cable
................. 5.14
Parking Brake Rear Cable (Drum Brakes)
..... 5.14
Parking Brake Rear Cable (Disc Brakes)
...... 5.15
Brake Lining Inspection
..................... 5.15
............. Inspecting and Refinishing Rotors 5-15
Thickness
Variat~on Check ................. 5.15
Lateral
Runout Check ..................... 5.15
Rotor Tolerance and Surface Finish
.......... 5.16
Refinishing Brake Rotors
.................. 5-16
lnspecting and Refinishing Brake
Drums
................................. 5-16
Cracked Scored, or Grooved Drum
.......... 5.16
Out-of-Round or Tapered Drum
............. 5.16
Refinishing Brake Drums
.................. 5.16
Brake Drum Balance
..................... -5-16
Combination Valve ......................... 5.17
Testing Combination Valve Electrical
............................... Circuit 5.17
Testing Combination Valve Warning
.......................... Lamp Switch 5.17
.......... Combination Valve Replacement 5.17
............ Power Brake Vacuum Hose Filter 5.17
Unit Repair
................ Composite Master Cylinder .5A 3.1
Disc Brake Caliper Assembly
....................... 300013100 Series 581 -1
Disc Brake Caliper Assembly
3548 Series
........................... .5B 6.1
........ Direct Torque Drum Brake Assembly .5C 3.1
Power Head Assembly
-
.................... Tandem Diaphragm .5D 2.1
.............. Specifications and Special Tools 5F-1

5-2 BRAKES
GENERAL DESCRIPTION
COMPOSIE EASTER CYLINDER
This vehicle uses a composite master cylinder which has
an aluminum body and a clear nylon reservoir with fluid
level indicators. The master cylinder uses a "quick take-up" feature in the
rear chamber to reduce pedal travel which may result from
increased fluid displacement required to move the caliper
piston. The quick take-up master cylinder includes a spring
loaded ball check valve which holds pressure in the
large-
diameter rear chamber. When the brake is first applied, the
movement of the rear piston causes fluid to be displaced
forward, past the primary piston primary seal and into the
primary high pressure chamber, which feeds the front
brakes. At a predetermined pressure, 480-690
kPa (70-100
mi), the ball unseats and fluid from the largi! rear bore is
disblaced past the ball and into the reservoir. The primary
and secondary high pressure chambers supply pressure to
the front and rear brakes, respectively, in the usual way.
When the pedal is released, the large-bore chamber is filled
with fluid by drawing fluid from the reservoir around the
quick take-up lip seal, and also through a small orifice in the
ball seat.
BRAKE FLUID LEVEL INDICATOR
(Figure 1)
The nylon master cylinder reservoir has two windows
which allow the brake fluid level to be checked without
removal of the reservoir cover.
OPERATION OF DISC BRAKE
When the brakes are applied, fluid pressure behind the
caliper piston increases. Pressure is exerted equally
against the bottom of the piston and also against the bottom
of the piston bore. The pressure applied to the piston is
transmitted to the inner shoe and lining, forcing the lining
against the inner rotor surface. The pressure applied to the
bottom of the piston bore forces the caliper to slide on the
Figure
1 Master Cylinder Reservoir Window (Typical) mounting bolts toward the inner side,
or toward the car.
Since the caliper is one piece, this movement toward the
car causes the outer section of the caliper to apply pressure
against the back of the outer shoe and lining assembly,
forcing the lining against the outer rotor surface. As line
pressure increases, the shoe and lining assemblies are
pressed against the rotor surfaces with increased force,
bringing the car to a stop. When line pressure is released,
the seal and seal groove cause the piston to be slightly
retracted, resulting in less drag on the rotor by the shoe and
lining assembly.
Outward movement of the piston and inward movement
of the caliper automatically compensate for lining wear. As
the linings wear, the increased area behind the piston is
filled with brake fluid from the master cylinder reservoir.
OPERATION OF DRUM BRAKE
The drum brake assembly is a duo-servo design. In the
duo-servo brake, the force that the wheel cylinder applies to
the primary shoe is
multipled by the primary lining friction to
provide a very high force applied to the secondary shoe.
Torque from the brake shoes is transferred through the anchor pin to the axle flange. Adjustment is automatic when
the brakes are applied while the car is backing up.
OPERATION OF COMBINATION VALVE
The metering, or hold-off section of the combination
valve, limits pressure to the front disc brakes until a prede-
termined front input pressure is reached, approximating
the pressure to overcome the rear shoe and lining retractor
springs. There is no restriction at inlet pressures below 20
kPa (3 psi) to allow for pressure equalization during non
apply periods.
To prevent early rear wheel lock-up under heavy braking
loads, the proportioning section of the combination valve
proportions outlet pressure to the rear brakes after a prede-
termined rear input pressure has been reached.
The valve has a by-pass feature which insures full system
pressure to the rear brakes in the event of a front brake
system failure. Similarly, full front pressure is retained in
the event of a rear brake pressure failure.
BRAKE PRESSURE DIFFERENTIAL
WARNING
SWITCH
The pressure differential warning switch constantly com-
pares brake pressure in both parts of the system. The
switch will activate the "BRAKE" warning lamp on the
instrument panel in a failure in either part. The combination
valve is designed so the switch will stay in the "warning"
position once a failure has occurred. The lamp can only be
turned off by repairing the failure and applying a pedal force
as required to develop up to 3100
kPa (450 psi) line pres-
sure.

BRAKES 5-3
DIAGNOSIS AND INSPECTION
BRAKE SYSTEM TESTING
(Figures
2 through 4)
Brakes should be tested on dry, clean, reasonably
smooth and level roadway. A true test of brake performance
cannot be made if the roadway is wet, greasy or covered
with loose dirt so that all tires do not grip the road equally.
Testing will also be affected if the roadway is crowned
which would throw the weight of the car toward the wheels
on one side. If the roadway is too rough, the wheels will tend
to bounce. Test brakes at different car speeds with both light and
heavy pedal pressure, avoid locking the brakes and sliding
the tires. Locked brakes and sliding tires do not indicate
brake efficiency, because heavily braked, but turning
wheels will stop the car in less distance than locked brakes.
More tire-to-road friction is present with a heavily braked
turning tire than with a sliding tire. The brake system is designed and balanced to avoid
locking the wheels, except at very high deceleration levels.
The shortest stopping distance and best control is achieved
without brake lock-up.
Because of high deceleration capability, a firmer pedal
may be felt at higher deceleration levels.
External Conditions That Affect Brake Performance
1. Tires. Tires having unequal contact and grip on road
will cause unequal braking. Tires must be equally
inflated and tread pattern of right and left tires must
be approximately equal.
2. Car Loading. A heavily loaded car requires more
braking effort. When a car has unequal loading, the
most heavily loaded wheels require more braking
power than others.
3. Wheel Alignment. Misalignment of the wheels, par-
ticularly excessive camber and caster, will cause the
brakes to pull to one side.
4. Front Wheel Bearings. A loose front wheel bearing
BRAKE FLUID LEAKS
With engine running at idle and the transmission in neu-
tral, depress the brake pedal and hold a constant foot pres-
sure.
If the pedal gradually falls away with the constant
pressure, the hydraulic system may be leaking. Perform a
visual check to confirm any suspected leak.
Check the master cylinder fluid levels. While a slight drop
in reservoir level does result from normal lining wear, an
abnormally low level in either reservoir indicates
a leak in
the system. The hydraulic system may be leaking either
internally or externally. See "Master Cylinder Check."
Also, the system may appear to pass this test but still have
slight leakage.
If fluid levels are normal, check the vacuum booster
pushrod length. If an incorrect length pushrod is found,
adjust or replace the
pushrod. Check the service brake
pedal travel and the parking brake adjustment.
When checking the fluid levels, the master cylinder reser-
voir may be as low as
25 mm (1 inch) from the top if the front
linings are worn. This is not abnormal.
MASTER CYLINDER CHECK
These checks will help locate some master cylinder mal-
functions. Use the Brake Diagnosis Charts to help isolate
the problem if it is not found by using these tests.
1. Check for a cracked master cylinder casting or brake
fluid around the master cylinder. Leaks are indicated
only if there is at least a drop of fluid. A damp condi-
tion is not abnormal.
2. Check for a binding pedal linkage.
3. Disassemble the master cylinder and check for swol-
len or stretched piston
seal(s). If swollen seals are
found, substandard or contaminated brake fluid
should be suspected.
If contaminated, all compo-
nents should be disassembled and cleaned. All rub-
ber components should be replaced and all the pipes
should be flushed.
permits the front wheel to tilt and lose contact with the
SUBSTANDARD OR CONTAMINATED brake shoe linings causing erratic brake operation. BRAKE FLUID
WARNING LAMP OPERATION
The brake system uses a single red "BRAKE" warning
lamp located in the instrument panel cluster. When the
ignition switch is in the "START" position, the "BRAKE"
warning lamp should come on. It should go off when the
ignition switch returns to the "RUN" position.
The following conditions will activate the "BRAKE"
warning lamp:
1. Parking brake applied. The lamp should be on when
tfie parking brake is applied and the ignition switch is
"ON."
2. Pressure differential switch detects a failure. See
"Brake Pressure Differential Warning Switch" in this
section. Improper
brake fluid, mineral oil or water in the fluid may
cause the brake fluid to boil or the rubber components to
deteriorate.
If piston cups are swollen, the rubber parts have dete-
riorated. This deterioration may also be seen by swollen
wheel cylinder piston cups on the drum brake wheels or a
swollen master cylinder cover diaphragm.
If rubber deterioration is evident, disassemble all hydrau-
lic parts and wash with alcohol. Dry these parts with com-
pressed air before assembly to keep alcohol out of the
system. Replace all rubber parts in the system, including
hoses. Check for fluid on the linings. If excessive fluid is
found, replace the linings.
If master cylinder piston seals are satisfactory, check for
leakage or excessive heat conditions. If condition is not
found, drain fluid, flush with brake fluid, fill and bleed the
system.

5-8 BRAKES
1 -PEDAL 4-SWITCH
(WITH CRUISE CONTROL)
2- RETAINER
5-PEDAL SUPPORT
3-SWITCH
I lWlO CRUISE CONTROLl J10003-5-F
Figure 6 Stoplamp Switch Adjustment
brake pipe is disconnected at one wheel, only that wheel
cylinderlcaliper needs to be bled. If pipes are disconnected
at any fitting located between master cylinder and brakes,
then the brake system served by the disconnected pipe
must be bled.
Manual Bleeding (Figure
7)
Tools Required:
J 21472 Bleeder Wrench
J 28434 Rear Wheel Cylinder Bleeder Wrench
The time required to bleed the hydraulic system can
be reduced if the master cylinder is filled with fluid and
as much air as possible is expelled before the cylinder is
installed on the vehicle.
Power brakes require removing the vacuum reserve by
applying the brakes several times with the engine off. Care
must be taken to prevent brake fluid from contacting any
painted surface.
1. Fill the master cylinder reservoirs with brake fluid and
keep at least half full of fluid during the bleeding oper-
ation.
2.
If the master cylinder is known or suspected to have
air in the bore, then it must be bled before any wheel
cylinder or caliper in the following manner:
a. Disconnect the forward (blind end) brake pipe
connection at the master cylinder.
b. Allow brake fluid to fill the master cylinder bore
until it begins to flow from the forward pipe con-
nector port.
c. Connect the forward brake pipe to the master
cylinder and tighten. d.
Depress the brake pedal slowly one time and
hold. Loosen the forward brake pipe connec-
tion at the master cylinder to purge air from the
bore. Tighten the connection and then release
the brake pedal slowly. Wait
15 seconds.
Repeat the sequence, including the
15 second
wait, until all air is removed from the bore.
e. After all air has been removed at the forward
connection, repeat step d and bleed the master
cylinder at the rear (cowl) connection.
f. If it is known that the calipers and wheel cylin-
ders do not
coiitain any air, then it will not be
necessary to bleed them.
Individual wheel cylinders or calipers are bled only
after all air is removed from master cylinder.
a. Place a proper size box end wrench or
J 21 472
over the bleeder valve. Rear wheel cylinder
bleeder screws require tool
J 28434. Attach a
clear tube over bleeder valve and allow tube to
hang submerged in a clear container partially
filled with brake fluid. Depress the brake pedal
slowly one time and hold. Loosen the bleeder
valve to purge the air from the cylinder. Tighten
bleeder screw and slowly release pedal. Wait
15 seconds. Repeat the sequence, including
the 15 second wait until all air is removed. It may
be necessary to repeat the sequence ten or
more times to remove all the air. Rapid pumping
of the brake pedal pushes the master cylinder
secondary piston down the bore in a way that
makes it difficult to bleed the rear side of the
system.
If it is necessary to bleed all of the calipers or wheel
cylinders, the following conventional sequence
should be followed: a. right rear
b. left rear
c. right front
d. left front
Check the brake pedal for "sponginess" and the
"BRAKE" warning lamp for indication of unbalanced
pressure. Repeat entire bleeding procedure to cor-
rect either of these two conditions.
Pressure Bleeding (Figures
7 and 8)
Tools Required:
J 21472 Bleeder Wrench
J 28434 Rear Wheel Cylinder Bleeder Wrench
J 29532 Bleeder
J 29567 Bleeder Adapter
J 35856 Proportioning Valve Depressor
NOTICE: Pressure bleeding equipment must be
the diaphragm type and must have a rubber dia-
phragm between the air supply and the brake fluid to
prevent air, moisture, oil and other contaminants
fram entering the hydraulic system. It is very impor-
tant that the correct master cylinder bleeder adapter
be used to avoid possible damage to the master
cylinder reservoir.
1. Install J 29567 to the master cylinder reservoir.
2. Make sure the pressure tank is at least
lh full of Delco
Supreme $1 1 brake fluid or equivalent. The bleeder
must be bled each time fluid is added.

BRAKES 5-9
TUBE hlUST BE
SUBMERGED IN
Figure 7 Bleeding Brakes
3. Charge the bleeder to 140-172
kPa (20-25 psi).
4. Connect line to adapter. Open the line valve and
depress bleed off valve on top of adapter until a few
drops of fluid appear.
5. Rear drum brakes require manual override of the
combination valve to permit flow to the front wheels. Use
J 35856 to hold the valve stem open when pres-
sure bleeding.
6. Raise car. See Section
OA.
7. Bleed the brakes in the following sequence:
a. right rear
b. left rear
c. right front
d. left front
8. Place a proper size box end wrench or
J 21472 over
the bleeder valve. Attach a clear tube over valve and
allow tube to hang submerged in a clear container
partially filled with brake fluid. When bleeding drum
brakes, use
J 28434 on the bleeder screw. Attach the
bleeder tubing to the tool and submerge the other end
in a clean container partially filled with brake fluid.
9. Open the bleeder valves at least 3/4 turn and allow
flow to continue until no air is seen in the fluid.
10. Close the bleeder valves or screws.
Be sure they seal.
11. Repeat steps
7 through 10 until all calipers and wheel
cylinders have been bled.
12. Lower car. See Section OA.
13. Check the brake pedal for "sponginess" and the
"BRAKE" warning lamp for indication of unbalanced
pressure.
* Repeat entire bleeding procedure to correct
either of these two conditions.
14. Remove brake bleeding equipment from master cyl-
inder.
FLUSHING BRAKE HYDRAULIC SYSTEM
It is recommended that the complete hydraulic system be
thoroughly flushed with clean brake fluid whenever new
parts are installed in the hydraulic system.
1 - MASTER CYLINDER
u 2 - HOSE TO BLEEDER
Figure 8 Pressure Bleeding Adapter (Typical)
The system must be flushed if there is any doubt about
the grade of fluid in the system or if fluid has been used
which contains the slightest trace of mineral oil.
All rubber parts that have been used with contaminated
fluid must be replaced.
BRAKE PIPE REPLACEMENT
(Figures
9 through 11)
Tool Required:
J 29803 I.S.O. Flaring Tool
CAUTION: Never use copper tubing because
copper is subject to fatigue cracking and corro-
sion which could result in brake failure. Use dou-
ble-walled steel tubing.
I.S.O. Flare
1. Obtain the recommended tubing and steel fitting nuts
of the correct size. Outside diameter of tubing is used
to specify size.
2. Cut tubing to length. Correct length may be deter-
mined by measuring old pipe using a string and
adding 3mm ('la-inch) for each I.S.O. flare.
3. Make sure fittings are installed before starting flare.
Flare tubing ends using I.S.O. flaring kit
J 29803. Fol-
low instructions included in tool set.
4. Bend pipe assembly to match old pipe using a tubing
bender. Clearance of
19mm (314-inch) from all moving
parts and
13mm (lh-inch)from all vibrating parts must
be maintained.
BRAKE HOSE INSPECTION
0 inspect
The flexible hydraulic brake hoses, which transmit
hydraulic pressure from the steel brake lines on the body to
the rear axle and the calipers, should be inspected at least
twice a year when the car is on a lift for lubrication. The

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

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)