tra DODGE NEON 2000 Service Owner's Guide

Driveshafts used on both the right and left sides of
the vehicle use a tuned rubber damper weight
mounted to the interconnecting shaft (Fig. 1). The
damper weight applications vary by which side of the
vehicle the driveshaft is located on and the transmis-
sion application of the vehicle. When replacing a
driveshaft, be sure the replacement driveshaft has
the same damper weight as the original.
Both driveshaft assemblies use the same type of
inner and outer joints. The inner joint of both drive-
shaft assemblies is a tripod joint, and the outer joint
of both driveshaft assemblies is a Rzeppa joint. Both
tripod joints and Rzeppa joints are true constant
velocity (C/V) joint assemblies. The inner tripod joint
allows for the changes in driveshaft length through
the jounce and rebound travel of the front suspen-
sion.
On vehicles equipped with ABS brakes, the outer
C/V joint is equipped with a tone wheel used to
determine vehicle speed for ABS brake operation.
The inner tripod joint of both driveshafts is splined
into the transaxle side gears. The inner tripod joints
are retained in the side gears of the transaxle using
a snap ring located in the stub shaft of the tripod
joint. The outer C/V joint has a stub shaft that is
splined into the wheel hub and retained by a single
piece steel hub nut (Fig. 2). The hub nut is a locking
style; the nut lock, anti-rattle washer, and cotter pin
are not necessary.NOTE: This vehicle does not use a rubber±lip bear-
ing seal as on previous front±wheel±drive cars to
prevent contamination of the front wheel bearing.
On these vehicles, the face of the outer C/V joint
fits deeply into the steering knuckle, using a close
outer C/V joint±to±steering knuckle fit. This design
deters direct water splash on bearing seal while
allowing any water that gets in, to run out the bot-
tom of the steering knuckle bearing bore. It is
important to thoroughly clean the outer C/V joint
and the wheel bearing area in the steering knuckle
before it is assembled after servicing.
DIAGNOSIS AND TESTING
DRIVESHAFT DIAGNOSIS
VEHICLE INSPECTION
(1) Check for grease in the vicinity of the inboard
tripod joint and outboard C/V joint; this is a sign of
inner or outer joint seal boot or seal boot clamp dam-
age.
(2) A light film of grease may appear on the right
inner tripod joint seal boot; this is considered normal
and should not require replacement of the seal boot.
The right inner tripod joint seal boot is made of sili-
cone rubber; which will allow the weeping (sweating)
of the joint lubricant to pass through it while in oper-
ation.
NOISE AND/OR VIBRATION IN TURNS
A clicking noise and/or a vibration in turns could
be caused by one of the following conditions.
(1) Damaged outer C/V or inner tripod joint seal
boot or seal boot clamps. This will result in the loss
and/or contamination of the joint grease, resulting in
inadequate lubrication of the joint.
(2) Noise may also be caused by another compo-
nent of the vehicle coming in contact with the drive-
shafts.
CLUNKING NOISE DURING ACCELERATION
This noise may be a result of one of the following
conditions:
(1) A torn seal boot on the inner or outer joint of
the driveshaft assembly.
(2) A loose or missing clamp on the inner or outer
joint of the driveshaft assembly.
(3) A damaged or worn driveshaft C/V joint.
Fig. 2 Driveshaft Retaining Nut
1 ± DRIVESHAFT
2 ± HUB
3 ± HUB NUT
3 - 2 DIFFERENTIAL AND DRIVELINEPL
DESCRIPTION AND OPERATION (Continued)

SHUDDER OR VIBRATION DURING ACCELERATION
(1) A worn or damaged driveshaft inner tripod
joint.
(2) A sticking tripod joint spider assembly (inner
tripod joint only).
(3) Improper wheel alignment. See Wheel Align-
ment in this group for alignment checking and set-
ting procedures and specifications.
VIBRATION AT HIGHWAY SPEEDS
(1) Foreign material (mud, etc.) packed on the
backside of the wheel(s).
(2) Out of balance front tires or wheels. See Group
22, Wheels And Tires for the required balancing pro-
cedure.
(3) Improper tire and/or wheel runout. See Group
22, Wheels And Tires for the required runout check-
ing procedure.
REMOVAL AND INSTALLATION
DRIVESHAFTS
CAUTION: Boot sealing is vital to retain special
lubricants and to prevent foreign contaminants
from entering the C/V joint. Mishandling, such as
allowing the assemblies to dangle unsupported, or
pulling or pushing the ends can cut boots or dam-
age C/V joints. During removal and installation pro-
cedures, always support both ends of the driveshaft
to prevent damage.
REMOVAL
CAUTION: The driveshaft, when installed, acts as a
bolt and secures the front hub/bearing assembly. If
vehicle is to be supported or moved on its wheels
with a driveshaft removed, install a PROPER±SIZED
BOLT AND NUT through front hub. Tighten bolt and
nut to 203 N´m (150 ft. lbs.). This will ensure that
the hub bearing cannot loosen.
(1) Disconnect battery negative cable.
(2) Place transaxle in gated park.
(3) Raise vehicle on hoist.
(4) Remove wheel and tire assembly (Fig. 3).(5) Remove the driveshaft to hub and bearing
retaining nut (Fig. 4).
(6) If equipped with ABS, disconnect the front
wheel speed sensor and secure harness out of the
way.
Fig. 3 Wheel and Tire Removal
1 ± WHEEL/TIRE ASSY.
2 ± LUG NUT (5)
3 ± HUB
Fig. 4 Driveshaft Retaining Nut Removal
1 ± DRIVESHAFT
2 ± HUB
3 ± HUB NUT
PLDIFFERENTIAL AND DRIVELINE 3 - 3
DIAGNOSIS AND TESTING (Continued)

(11) Remove the inner tripod joints from the side
gears of the transaxle using a punch to dislodge the
inner tripod joint retaining ring from the transaxle
side gear. If removing the right side inner tripod
joint, position the punch against the inner tripod
joint (Fig. 9). Strike the punch sharply with a ham-
mer to dislodge the right inner joint from the side
gear. If removing the left side inner tripod joint, posi-
tion the punch in the groove of the inner tripod joint
(Fig. 10). Strike the punch sharply with a hammer to
dislodge the left inner tripod joint from the side gear.(12) Hold inner tripod joint and interconnecting
shaft of driveshaft assembly (Fig. 11). Remove inner
tripod joint from transaxle by pulling it straight out
of transaxle side gear and transaxle oil seal.When
removing tripod joint, do not let spline or snap
ring drag across sealing lip of the transaxle to
tripod joint oil seal. When tripod joint is
removed from transaxle, some fluid will leak
out.
Fig. 8 Removing Stub Axle From Hub/Bearing
1 ± TOOL 6790
Fig. 9 Disengaging Right Inner Tripod Joint from
Transaxle
1 ± TRANSAXLE
2 ± RIGHT INNER TRIPOD JOINT
3 ± PUNCH
Fig. 10 Disengaging Left Inner Tripod Joint from
Transaxle
1 ± FRONT SUSPENSION CROSSMEMBER
2 ± DRIFT
3 ± TRANSAXLE
4 ± DRIVESHAFT INNER TRIPOD JOINT
5 ± NOTCH
Fig. 11 Tripod Joint Removal from Transaxle
1 ± INNER TRIPOD JOINT
2 ± TRANSAXLE
3 ± SPLINE
4 ± OIL SEAL
5 ± SNAP RING
6 ± INTERCONNECTING SHAFT
PLDIFFERENTIAL AND DRIVELINE 3 - 5
REMOVAL AND INSTALLATION (Continued)

CAUTION: The driveshaft, when installed, acts as a
bolt and secures the front hub/bearing assembly. If
vehicle is to be supported or moved on its wheels
with a driveshaft removed, install a PROPER±SIZED
BOLT AND NUT through front hub. Tighten bolt and
nut to 203 N´m (150 ft. lbs.). This will ensure that
the hub bearing cannot loosen.
INSTALLATION
(1) Thoroughly clean spline and oil seal sealing
surface, on tripod joint. Lightly lubricate oil seal
sealing surface on tripod joint with fresh clean trans-
mission lubricant.
(2) Holding driveshaft assembly by tripod joint and
interconnecting shaft, install tripod joint into tran-
saxle side gear as far as possible by hand.
(3) Carefully align tripod joint with transaxle side
gears. Then grasp driveshaft interconnecting shaft
and push tripod joint into transaxle side gear until
fully seated.Test that snap ring is fully engaged
with side gear by attempting to remove tripod
joint from transaxle by hand. If snap ring is
fully engaged with side gear, tripod joint will
not be removable by hand.
(4) Clean all debris and moisture out of steering
knuckle (Fig. 12).
(5) Ensure that front of outer C/V joint, which fits
into steering knuckle (Fig. 13), is free of debris and
moisture before assembling into steering knuckle.(6) Slide driveshaft back into front hub. Install
steering knuckle onto the ball joint stud (Fig. 14).
NOTE: At this point, the outer joint will not seat
completely into the front hub. The outer joint will be
pulled into hub and seated when the hub nut is
installed and torqued.
(7) Install aNEWsteering knuckle to ball joint
stud bolt and nut (Fig. 14). Tighten the nut and bolt
to 95 N´m (70 ft. lbs.).
Fig. 12 Steering Knuckle to C/V Joint Sealing Area
1 ± STEERING KNUCKLE
2 ± WHEEL BEARING
3 ± FRONT HUB
4 ± THIS AREA OF THE STEERING KNUCKLE IS TO BE FREE
OF ALL DEBRIS AND MOISTURE BEFORE INSTALLING
DRIVE SHAFT IN STEERING KNUCKLE
Fig. 13 Outer C/V Joint Inspection
1 ± OUTER C/V JOINT
2 ± THIS AREA OF OUTER C/V JOINT MUST BE FREE OF ALL
DEBRIS AND MOISTURE, BEFORE INSTALLATION INTO
STEERING KNUCKLE.
Fig. 14 Driveshaft Installation Into Hub And Steering
Knuckle
1 ± NUT
2 ± BOLT
3 ± BALL JOINT
3 - 6 DIFFERENTIAL AND DRIVELINEPL
REMOVAL AND INSTALLATION (Continued)

(8) Clean all foreign matter from threads of drive-
shaft outer stub axle. Install hub nut onto the
threads of the stub axle and tighten nut to 244 N´m
(180 ft. lbs.) (Fig. 15).
(9) Install front wheel and tire assembly. Install
front wheel lug nuts (Fig. 16) and tighten to 128 N´m
(95 ft. lbs.).(10) Check for correct fluid level in transaxle
assembly. Refer to Group 21 Transaxle, for the cor-
rect fluid level checking procedure for the type of
transaxle being checked.
(11) Lower vehicle.
(12) Connect battery negative cable.
DISASSEMBLY AND ASSEMBLY
DRIVESHAFT RECONDITION
NOTE: The only service that is to be performed on
the driveshaft assemblies is the replacement of the
driveshaft seal boots.
If any failure of internal driveshaft components is
diagnosed during a vehicle road test or disassembly
of the driveshaft, the driveshaft will need to be
replaced as an assembly.
NOTE: Lubricant requirements and quantities are
different for inner joints than for outer joints. Use
only the recommended lubricants in the required
quantities when servicing driveshaft assemblies.
See (Fig. 17) for the exploded view of the front
driveshaft components.
INNER TRIPOD JOINT SEAL BOOT
REMOVAL
To remove sealing boot from driveshaft for replace-
ment, the driveshaft assembly must be removed from
the vehicle. See Driveshaft Removal and Installation
in this section for the required driveshaft removal
and replacement procedure.
The inner tripod joints use no internal retention in
the tripod housing to keep the spider assembly in the
housing. Therefore, do not pull on the interconnect-
ing shaft to disengage tripod housing from transmis-
sion stub shaft. Removal in this manner will cause
damage to the inboard joint sealing boots.
(1) Remove the driveshaft requiring boot replace-
ment from the vehicle. See Driveshaft Removal and
Installation in this section for the required driveshaft
removal procedure.
(2) Remove large boot clamp that retains inner tri-
pod joint sealing boot to tripod joint housing (Fig. 18)
and discard. Then remove small clamp that retains
inner tripod joint sealing boot to interconnecting
shaft and discard. Remove the sealing boot from the
tripod housing and slide it down the interconnecting
shaft.
Fig. 15 Driveshaft Retaining Nut Installation
1 ± DRIVESHAFT
2 ± HUB
3 ± HUB NUT
Fig. 16 Wheel and Tire Installation
1 ± WHEEL/TIRE ASSY.
2 ± LUG NUT (5)
3 ± HUB
PLDIFFERENTIAL AND DRIVELINE 3 - 7
REMOVAL AND INSTALLATION (Continued)

DESCRIPTION AND OPERATION
BASE BRAKE SYSTEM OPERATION
When a vehicle needs to be stopped, the driver
applies the brake pedal. The brake pedal pushes the
input rod of the power brake booster into the booster.
The booster uses vacuum to ease pedal effort as force
is transferred through the booster to the master cyl-
inder. The booster's output rod pushes in the master
cylinder's primary and secondary pistons applying
hydraulic pressure through the chassis brake tubes
and proportioning valves (rear only) to the brakes at
each tire and wheel assembly.
Front disc brakes control the braking of the front
wheels; rear braking is controlled by rear drum
brakes as standard equipment. Rear disc brakes and
an antilock brake system (ABS) with traction control
are optional.
The hydraulic brake system is diagonally split on
both the non-antilock and antilock braking systems.
This means the left front and right rear brakes are
on one hydraulic circuit and the right front and left
rear are on the other.
Vehicles equipped with the optional antilock brake
system (ABS) use a system designated Mark 20e.
This system shares most base brake hardware used
on vehicles without ABS. A vehicle equipped with
ABS, however, uses a different master cylinder and
brake tubes. Also included in the ABS system is an
integrated control unit (ICU) and four wheel speed
sensors. These components are described in detail in
the ANTILOCK BRAKE SYSTEM section in this
group of the service manual. All vehicles with ABS
come standard with four-wheel-disc brakes and trac-
tion control.
The parking brakes are hand-operated. When
applied, the parking brake lever pulls on cables that
actuate brake shoes at each rear wheel. The parking
brake lever has an automatic adjusting feature that
takes up any excessive slack in the parking brake
cable system.
BASE BRAKE SYSTEM COMPONENTS
BRAKE PEDAL
A suspended-type brake pedal is used on this vehi-
cle. The pedal pivots on a shaft mounted in the pedal
support bracket under the instrument panel. The
pedal connects to the power brake booster input rod
and pushes it in when the pedal is applied.
The brake pedal and it's pad are serviceable sepa-
rately.
POWER BRAKE BOOSTER
There are two different power brake booster
designs, although externally they appear the same.
All vehicles use a 205 mm tandem diaphragm power
brake booster. The two boosters are internally tuned
differently depending on whether the vehicle is
equipped with the standard front disc/rear drum
brake combination or the optional front disc/rear disc
(four-wheel disc) brake combination. If the power
brake booster requires replacement, be sure it is
replaced with the correct part.
The power brake booster can be identified by the
tag attached to the body of the booster assembly (Fig.
1). This tag contains the following information: The
production part number of the power brake booster,
the date it was built and who manufactured it.
The power brake booster reduces the amount of
force required by the driver to obtain the necessary
hydraulic pressure to stop the vehicle.
The power brake booster is vacuum-operated. The
vacuum is supplied from the intake manifold on the
engine through the power brake booster check valve
(Fig. 2).
As the brake pedal is depressed, the power booster
input rod moves forward. This opens and closes
valves in the power brake booster, allowing atmo-
spheric pressure to enter on one side of a diaphragm.
Engine vacuum is always present on the other side.
This difference in pressure forces the output rod of
the power booster out against the primary piston of
the master cylinder. As the pistons in the master cyl-
inder move forward, hydraulic pressure is created in
the brake system.
Fig. 1 Master Cylinder and Power Brake Booster
1 ± POWER BRAKE BOOSTER PARTS IDENTIFICATION TAG
2 ± POWER BRAKE BOOSTER
3 ± BRAKE FLUID PRESSURE SWITCH
4 ± MASTER CYLINDER
5 - 2 BRAKESPL

Proportioning valves balance front to rear braking
by controlling the brake fluid hydraulic pressure to
the rear brakes. Under light pedal application, the
proportioning valve allows normal fluid flow to the
rear brakes. Under higher pedal effort, the valve
reduces fluid pressure to the rear brakes.
The non-antilock master cylinder is a four-outlet
design with two screw-in proportioning valves
attached directly to the master cylinder housing (Fig.
3). One proportioning valve controls each rear brake.
BRAKE TUBES AND HOSES
The purpose of the brake tubes and flex hoses is to
transfer the pressurized brake fluid developed by the
master cylinder to the brakes at each wheel of the
vehicle. The flex hoses connect the chassis brake
tubes, which are mounted to the vehicle's underbody,
to the brake at each wheel, allowing for movement of
the vehicle's suspension. The brake tubes are steel
with a corrosion-resistant nylon coating applied to
the external surfaces. The flex hoses are made of
reinforced rubber.
DISC BRAKES (FRONT)
The front disc brakes consist of the following com-
ponents (Fig. 4):
²Brake caliper - single-piston, floating type
²Brake shoes and linings
²Brake rotorWhen the brakes are applied, fluid pressure is sent
to each brake caliper. The pressure at the caliper is
exerted equally against the caliper piston. The pres-
sure applied to the piston is transmitted directly to
the inboard brake shoe. This forces the shoe lining
against the inner surface of the brake rotor. At the
same time, fluid pressure within the caliper piston
bore forces the caliper to slide inward on its guide
pins. This action brings the outboard shoe lining into
contact with the outer surface of the brake rotor.
This pressure on both sides of the brake rotor causes
friction, bringing the vehicle to a stop.
BRAKE CALIPER
The caliper is a one-piece casting with the inboard
side containing a single piston cylinder bore (Fig. 5).
The front disc brake caliper piston, is manufac-
tured from a phenolic compound. The outside diame-
ter of the caliper piston is 54 mm.
A square-cut rubber piston seal is located in a
machined groove in the caliper cylinder bore. This
provides a hydraulic seal between the piston and the
cylinder wall (Fig. 6). The piston seal is designed to
pull the piston back into the bore of the caliper when
the brake pedal is released. This maintains the
proper brake shoe-to-rotor clearance.
A rubber dust boot is installed in the cylinder bore
opening and in a groove in the piston (Fig. 6). This
prevents contamination in the bore area.
The caliper is mounted to the steering knuckle
using bushings, sleeves and two guide pin bolts (Fig.
5). The guide pin bolts thread directly into bosses on
the steering knuckle.
Two machined abutments on the steering knuckle
position the caliper. The guide pin bolts, sleeves, and
bushings control the side-to-side movement of the
caliper. All of the front brake force generated during
braking of the vehicle is taken up directly by the
steering knuckles of the vehicle.
BRAKE SHOES AND LININGS
There are two brake shoes mounted to each caliper,
one inboard and one outboard (Fig. 5). When brake
shoes are replaced, only brake shoes meeting the
original equipment manufacturer (OEM) formulation
(such as Mopartreplacement parts) should be used.
As front disc brake shoe linings wear, master cyl-
inder reservoir brake fluid level will drop. Fluid level
should be checked after replacing shoes.
Front disc brakes are equipped with an audible
wear indicator on the outboard brake pad (Fig. 5).
This sensor emits a sound when the brake lining
may need inspection or replacement.
Fig. 4 Front Disc Brakes
1 ± STEERING KNUCKLE
2 ± BRAKE PADS AND LININGS
3 ± BRAKE ROTOR
4 ± DRIVING HUB
5 ± CALIPER ASSEMBLY
5 - 4 BRAKESPL
DESCRIPTION AND OPERATION (Continued)

OTHER BRAKE CONDITIONS
CONDITION POSSIBLE CAUSES CORRECTION
BRAKES CHATTER 1. Rear brake drum out of round or
disc brake rotor has excessive
thickness variation.1. Isolate condition as rear or front.
Reface or replace brake drums or rotors
as necessary.
BRAKES DRAG (FRONT OR
ALL)1. Contaminated brake fluid. 1. Check for swollen seals. Replace all
system components containing rubber.
2. Binding caliper pins or bushings. 2. Replace pins and bushings
3. Binding master cylinder. 3. Replace master cylinder.
4. Binding brake pedal. 4. Replace brake pedal.
BRAKES DRAG (REAR
ONLY)1. Parking brake cables binding or
froze up.1. Check cable routing. Replace cables as
necessary.
2. Parking brake cable return spring
not returning shoes.2. Replace cables as necessary.
3. Service brakes not adjusted properly
(rear drum brakes only).3. Follow the procedure listed in the
adjustment section.
4. Obstruction inside the center
console preventing full return of the
parking brake cables.4. Remove console and remove
obstruction.
BRAKES GRAB 1. Contaminated brake shoe linings. 1. Inspect and clean, or replace shoes.
Repair source of contamination.
2. Improper power brake booster
assist.2. Refer to power brake booster in the
diagnosis and testing section.
EXCESSIVE PEDAL
EFFORT1. Obstruction of brake pedal. 1. Inspect, remove or move obstruction.
2. Low power brake booster assist. 2. Refer to power brake booster in the
diagnosis and testing section.
3. Glazed brake linings. 3. Reface or replace brake rotors as
necessary. Replace brake shoes.
4. Brake shoe lining transfer to brake
rotor.4. Reface or replace brake rotors as
necessary. Replace brake shoes.
EXCESSIVE PEDAL
TRAVEL (VEHICLE STOPS
OK)1. Air in brake lines. 1. Bleed brakes.
2. Rear drum brake auto-adjuster
malfunctioning.2. Inspect and replace drum brake
components as necessary. Adjust rear
brakes.
EXCESSIVE PEDAL
TRAVEL (PEDAL GOES TO
FLOOR - CAN'T SKID
WHEELS)1. Power brake booster runout
(vacuum assist).1. Check booster vacuum hose and
engine tune for adequate vacuum supply.
Refer to power brake booster in the
diagnosis and testing section.
EXCESSIVE PEDAL
TRAVEL (ONE FRONT
WHEEL LOCKS UP DURING
HARD BRAKING)1. One of the two hydraulic circuits to
the front brakes is malfunctioning.1. Inspect system for leaks. Check master
cylinder for internal malfunction.
5 - 10 BRAKESPL
DIAGNOSIS AND TESTING (Continued)

CONDITION POSSIBLE CAUSES CORRECTION
PEDAL PULSATES/SURGES
DURING BRAKING1. Rear brake drum out of round or
disc brake rotor has excessive
thickness variation.1. Isolate condition as rear or front.
Reface or replace brake drums or rotors
as necessary.
PEDAL IS SPONGY 1. Air in brake lines. 1. Bleed brakes.
2. Power brake booster runout
(vacuum assist).2. Check booster vacuum hose and
engine tune for adequate vacuum supply.
Refer to power brake booster in the
diagnosis and testing section.
PREMATURE REAR WHEEL
LOCKUP1. Contaminated brake shoe linings. 1. Inspect and clean, or replace shoes.
Repair source of contamination.
2. Inoperative proportioning valve
(non-ABS vehicles only).2. Test proportioning valves folowing
procedure listed in diagnosis and testing
section. Replace valves as necessary.
3. ABS EBD not functioning. 3. Refer to the ABS section and Chassis
Diagnostic Procedures manual.
4. Improper power brake booster
assist.4. Refer to power brake booster in the
diagnosis and testing section.
STOP LAMPS STAY ON 1. Brake lamp switch out of
adjustment.1. Adjust brake lamp switch.
2. Brake pedal binding. 2. Inspect and replace as necessary.
3. Obstruction in pedal linkage. 3. Remove obstruction.
4. Power Brake Booster not allowing
pedal to return completely.4. Replace power brake booster.
VEHICLE PULLS TO RIGHT
OR LEFT ON BRAKING1. Frozen brake caliper piston. 1. Replace frozen piston or caliper. Bleed
brakes.
2. Contaminated brake shoe lining. 2. Inspect and clean, or replace shoes.
Repair source of contamination.
3. Pinched brake lines. 3. Replace pinched line.
4. Leaking piston seal. 4. Replace piston seal or brake caliper.
5. Suspension problem. 5. Refer to the Suspension group.
PARKING BRAKE -
EXCESSIVE HANDLE
TRAVEL1. Rear brakes out of adjustment. 1. Adjust rear drum brake shoes, or rear
parking brake shoes on vehicles with rear
disc brakes.
POWER BRAKE BOOSTER
BASIC TEST
(1) With engine off, depress and release the brake
pedal several times to purge all vacuum from the
power brake booster.
(2) Depress and hold the pedal with light effort (15
to 25 lbs. pressure), then start the engine.
The pedal should fall slightly, then hold. Less effort
should be needed to apply the pedal at this time. If
the pedal fell as indicated, perform the VACUUM
LEAK TEST listed after the BASIC TEST. If thepedal did not fall, continue on with this BASIC
TEST.
(3) Disconnect the vacuum hose on the side of the
vacuum check valve that leads to the speed control,
then connect a vacuum gauge to the open vacuum
port on the valve.
(4) Start the engine.
(5) When the engine is at warm operating temper-
ature, allow it to idle and check the vacuum at the
gauge.
PLBRAKES 5 - 11
DIAGNOSIS AND TESTING (Continued)

If the vacuum supply is 12 inches Hg (40.5 kPa) or
more, the power brake booster is defective and must
be replaced. If the vacuum supply is below 12 inches,
continue on with this BASIC TEST.
(6) Shut off the engine.
(7) Connect the vacuum gauge to the vacuum ref-
erence port on the engine intake manifold.
(8)
Start the engine and observe the vacuum gauge.
If the vacuum is still low, check the engine tune
and repair as necessary. If the vacuum is above 12
inches, the hose or check to the booster has a restric-
tion or leak.
Once an adequate vacuum supply is obtained,
repeat the BASIC TEST.
VACUUM LEAK TEST
(1) Disconnect the vacuum hose on the side of the
power brake booster vacuum check valve that leads
to the speed control, then connect a vacuum gauge to
the open vacuum port on the valve.
(2) Remove the remaining hose on the vacuum
check valve that is not the vacuum supply hose com-
ing from the intake manifold. Cap off the open port
on the check valve.
(3) Start the engine.
(4) Allow the engine to warm up to normal operat-
ing temperature and engine idle.
(5) Using vacuum line pliers, close off the vacuum
supply hose near the booster and observe the vacuum
gauge.
If the vacuum drop exceeds 1.0 inch Hg (3.3 kPa)
in one minute, repeat the above steps to confirm the
reading. The vacuum loss should be less than 1.0
inch Hg in one minute time span. If the loss is more
than 1.0 inch Hg, replace the power brake booster. If
it is not, continue on with this test.
(6) Remove the pliers from the hose temporarily.
(7) Apply light effort (approximately 15 lbs. of
force) to the brake pedal and hold the pedal steady.
Do not move the pedal once the pressure is applied
or the test results may vary.
(8) Have an assistant reattach the pliers to the
vacuum supply hose.
(9) Allow 5 seconds for stabilization, then observe
the vacuum gauge.
If the vacuum drop exceeds 3.0 inches Hg (10 kPa)
in 15 seconds, repeat the above steps to confirm the
reading. The vacuum loss should be less than 3.0
inches Hg in 15 seconds time span. If the loss is
more than 3.0 inches Hg, replace the power brake
booster. If it is not, the booster is not defective.
DRUM BRAKE AUTOMATIC ADJUSTER
To properly test the drum brake automatic
adjuster, the aide of a helper inside the vehicle to
apply the brakes will be necessary.(1) Raise the vehicle. Refer to HOISTING in the
LUBRICATION AND MAINTENANCE group for the
proper lifting procedure.
(2) Remove the access plug from the rear adjust-
ment slot in each brake support plate.
(3) Insert a thin screwdriver in the adjustment
slot and push back the adjustment lever. With the
lever in this position, back the star wheel adjustment
off approximately 10 notches. This will eliminate the
possibility that the brake is at full adjustment, and
can be adjusted no further.
(4)
Remove the screwdriver from the adjustment slot.
(5) Watch the star wheel through the adjustment
slot, while a helper applies the brake pedal. As the
brake shoes apply, the adjustment lever should move
downward, turning the star wheel. A definite rotation
of the adjuster star wheel can be observed if the
automatic adjuster is working properly.
If the star wheel does not move as indicated, the
brake drum needs to be removed and further inspec-
tion of the rear brakes is necessary.
(6) If the star wheel is operating properly, readjust
the brakes. Refer to ADJUSTMENTS in this section
of this service manual group.
(7) Reinstall the adjustment slot access plug.
(8) Lower the vehicle.
BRAKE ROTOR
Any servicing of the rotor requires extreme care to
maintain the rotor within service tolerances to
ensure proper brake action.
Excessive runout or wobble in a rotor can increase
pedal travel due to piston knock-back. This increases
guide pin sleeve wear due to the tendency of the cal-
iper to follow the rotor wobble.
When diagnosing a brake noise or pulsation, the
machined disc braking surface should be checked and
inspected.
BRAKING SURFACE INSPECTION
Light braking surface scoring and wear is accept-
able. If heavy scoring or warping is evident, the rotor
must be refaced or replaced. Refer to SERVICE PRO-
CEDURES in this section of this group for informa-
tion on brake rotor machining.
Excessive wear and scoring of the rotor can cause
improper lining contact on the rotor's braking sur-
face. If the ridges on the rotor are not removed before
new brake shoes are installed, improper wear of the
shoes will result.
If a vehicle has not been driven for a period of
time, the rotor's braking surface will rust in the
areas not covered by the brake shoes at that time.
Once the vehicle is driven, noise and chatter from
the disc brakes can result when the brakes are
applied.
5 - 12 BRAKESPL
DIAGNOSIS AND TESTING (Continued)