tires CHRYSLER VOYAGER 2003 User Guide

TOE-OUT ON TURNS
Toe-out on turns is the relative positioning of the
front wheels while steering through a turn (Fig. 4).
This compensates for each front wheel's turning
radius. As the vehicle encounters a turn, the out-
board wheel must travel in a larger radius circle
than the inboard wheel. The steering system is
designed to make each wheel follow its particular
radius circle. To accomplish this, the front wheels
must progressively toe outward as the steering is
turned from center. This eliminates tire scrubbing
and undue tire wear when steering a vehicle through
a turn.
DYNAMIC TOE PATTERN
Dynamic toe pattern is the inward and outward toe
movement of the front and rear tires through the
suspension's jounce and rebound travel. As the vehi-
cle's suspension moves up and down, the toe pattern
varies. Toe pattern is critical in controlling the direc-
tional stability of the vehicle while in motion. Front
and rear dynamic toe pattern is preset by the factory
at the time the vehicle is assembled.
It is not necessary to check or adjust front or rear
dynamic toe pattern when doing a normal wheel
alignment. The only time dynamic toe pattern needs
to be checked or adjusted is if the frame of the vehi-
cle has been damaged.
STEERING AXIS INCLINATION (S. A. I.)
Steering axis inclination is the angle between a
true vertical line starting at the center of the tire at
the road contact point and a line drawn through the
center of the upper ball joint (or strut) and the lower
ball joint (Fig. 5). S.A.I. is built into the vehicle and
is not an adjustable angle. If S.A.I. is not within
specifications, a bent or damaged suspension compo-
nent may be the cause.
INCLUDED ANGLE (I. A.)
Included angle is the sum of the S.A.I. angle plus
or minus the camber angle, depending on whether or
not the wheel has positive or negative camber (Fig.
5). If camber is positive, add the camber angle to the
S.A.I. angle. If camber is negative, subtract the cam-
ber angle from the S.A.I. angle. Included angle is not
adjustable, but can be used to diagnose a frame mis-
alignment or bent suspension component (spindle,
strut).
Fig. 4 Toe-Out On Turns
1 - TOE-OUT ON TURNS
Fig. 5 S.A.I. and I.A.
1 - S.A.I.
2 - CAMBER
3 - I.A.
2 - 48 WHEEL ALIGNMENTRS
WHEEL ALIGNMENT (Continued)
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THRUST ANGLE
Thrust angle is the averaged direction the rear
wheels are pointing in relation to the vehicle's center
line (Fig. 6). The presence of negative or positive
thrust angle causes the rear tires to track improperly
to the left or right of the front tires (dog tracking).
²Negative thrust angle means the rear tires are
tracking to the left of the front tires.
²Positive thrust angle means the rear tires are
tracking to the right of the front tires.
Improper tracking can cause undue tire wear, a
lead or pull and a crooked steering wheel. Excessive
thrust angle can usually be corrected by adjusting
the rear wheel toe so that each wheel has one-half of
the total toe measurement.
DIAGNOSIS AND TESTING - SUSPENSION AND STEERING
CONDITION POSSIBLE CAUSES CORRECTION
Front End Whine On Turns 1. Defective wheel bearing 1. Replace wheel bearing
2. Incorrect wheel alignment 2. Check and reset wheel alignment
3. Worn tires 3. Replace tires
Front End Growl Or
Grinding On Turns1. Defective wheel bearing 1. Replace wheel bearing
2. Engine mount grounding 2. Check for motor mount hitting frame rail
and reposition engine as required
3. Worn or broken C/V joint 3. Replace C/V joint
4. Loose wheel lug nuts 4. Verify wheel lug nut torque
5. Incorrect wheel alignment 5. Check and reset wheel alignment
6. Worn tires 6. Replace tires
7. Front strut pin in upper strut mount 7. Replace the front strut upper mount and
bearing
Front End Clunk Or Snap
On Turns1. Loose lug nuts 1. Verify wheel lug nut torque
2. Worn or broken C/V joint 2. Replace C/V joint
3. Worn or loose tie rod 3. Tighten or replace tie rod end
4. Worn or loose ball joint 4. Tighten or replace ball joint
5. Worn/loose control arm bushing 5. Replace control arm bushing
6. Loose stabilizer bar. 6. Tighten stabilizer bar to specified torque
7. Loose strut mount to body
attachment7. Tighten strut attachment to specified
torque
8. Loose crossmember bolts 8. Tighten crossmember bolts to specified
torque
Fig. 6 Thrust Angle
RSWHEEL ALIGNMENT2-49
WHEEL ALIGNMENT (Continued)
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CONDITION POSSIBLE CAUSES CORRECTION
Front End Whine With
Vehicle Going Straight At A
Constant Speed1. Defective wheel bearing 1. Replace wheel bearing
2. Incorrect wheel alignment 2. Check and reset wheel alignment
3. Worn tires 3. Replace tires
4. Worn or defective transaxle gears
or bearings4. Replace transaxle gears or bearings
Front End Growl Or
Grinding With Vehicle
Going Straight At A
Constant Speed1. Engine mount grounding 1. Reposition engine as required
2. Worn or broken C/V joint 2. Replace C/V joint
Front End Whine When
Accelerating Or
Decelerating1. Worn or defective transaxle gears
or bearings1. Replace transaxle gears or bearings
Front End Clunk When
Accelerating Or
Decelerating1. Worn or broken engine mount 1. Replace engine mount
2. Worn or defective transaxle gears
or bearings2. Replace transaxle gears or bearings
3. Loose lug nuts 3. Verify wheel lug nut torque
4. Worn or broken C/V joint 4. Replace C/V joint
5. Worn or loose ball joint 5. Tighten or replace ball joint
6. Worn or loose control arm bushing 6. Replace control arm bushing
7. Loose crossmember bolts 7. Tighten crossmember bolts to specified
torque
8. Worn tie rod end 8. Replace tie rod end
Road Wander 1. Incorrect tire pressure 1. Inflate tires to recommended pressure
2. Incorrect front or rear wheel toe 2. Check and reset wheel toe
3. Worn wheel bearings 3. Replace wheel bearing
4. Worn control arm bushings 4. Replace control arm bushing
5. Excessive friction in steering gear 5. Replace steering gear
6. Excessive friction in steering shaft
coupling6. Replace steering coupler
7. Excessive friction in strut upper
bearing7. Replace strut bearing
Lateral Pull 1. Unequal tire pressure 1. Inflate all tires to recommended
pressure
2. Radial tire lead 2. Perform lead correction procedure
3. Incorrect front wheel camber 3. Check and reset front wheel camber
4. Power steering gear imbalance 4. Replace power steering gear
5. Wheel braking 5. Correct braking condition causing
lateral pull
Excessive Steering Free
Play1. Incorrect Steering Gear Adjustment 1. Adjust Or Replace Steering Gear
2. Worn or loose tie rod ends 2. Replace or tighten tie rod ends
3. Loose steering gear mounting bolts 3. Tighten steering gear bolts to specified
torque
4. Loose or worn steering shaft
coupler4. Replace steering shaft coupler
2 - 50 WHEEL ALIGNMENTRS
WHEEL ALIGNMENT (Continued)
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CONDITION POSSIBLE CAUSES CORRECTION
Excessive Steering Effort 1. Low tire pressure 1. Inflate all tires to recommended
pressure
2. Lack of lubricant in steering gear 2. Replace steering gear
3. Low power steering fluid level 3. Fill power steering fluid reservoir to
correct level
4. Loose power steering pump drive
belt4. Correctly adjust power steering pump
drive belt
5. Lack of lubricant in ball joints 5. Lubricate or replace ball joints
6. Steering gear malfunction 6. Replace steering gear
7. Lack of lubricant in steering coupler 7. Replace steering coupler
STANDARD PROCEDURE
STANDARD PROCEDURE - WHEEL ALIGNMENT
PRE-WHEEL ALIGNMENT INSPECTION
Before any attempt is made to change or correct
the wheel alignment, the following inspection and
necessary corrections must be made to ensure proper
alignment.
(1) Verify that the fuel tank is full of fuel. If the
tank is not full, the reduction in weight will affect
the curb height of the vehicle and the alignment
angles.
(2) The passenger and luggage compartments of
the vehicle should be free of any load that is not fac-
tory equipment.
(3) Check the tires on the vehicle. All tires must be
the same size and in good condition with approxi-
mately the same amount of tread wear. Inflate all
the tires to the recommended air pressure.
(4) Check the front wheel and tire assemblies for
excessive radial runout.
(5) Inspect lower ball joints and all steering link-
age for looseness, binding, wear or damage. Repair as
necessary.
(6) Check suspension fasteners for proper torque
and retighten as necessary.
(7) Inspect all suspension component rubber bush-
ings for signs of wear or deterioration. Replace any
faulty bushings or components before aligning the
vehicle.
(8) Check the vehicle's curb height to verify it is
within specifications. Refer to Curb Height Measure-
ment.
WHEEL ALIGNMENT SETUP
(1) Position the vehicle on an alignment rack.
(2) Install all required alignment equipment on
the vehicle per the alignment equipment manufactur-
er's instructions. On this vehicle, a four-wheel align-
ment is recommended.NOTE: Prior to reading the vehicle's alignment
readouts, the front and rear of vehicle should be
jounced. Induce jounce (rear first, then front) by
grasping the center of the bumper and jouncing
each end of vehicle an equal number of times. The
bumper should always be released when vehicle is
at the bottom of the jounce cycle.
(3) Read the vehicle's current front and rear align-
ment settings. Compare the vehicle's current align-
ment settings to the vehicle specifications for camber,
caster and toe-in. (Refer to 2 - SUSPENSION/
WHEEL ALIGNMENT - SPECIFICATIONS)
(4) If front camber and caster are not within spec-
ifications, proceed to CAMBER AND CASTER below.
If caster and camber are within specifications, pro-
ceed to TOE which can be found following CAMBER
AND CASTER. Rear camber, caster and toe are not
adjustable. If found not to be within specifications,
reinspect for damaged suspension or body compo-
nents and replace as necessary.
CAMBER AND CASTER
Camber and caster settings on this vehicle are
determined at the time the vehicle is designed, by
the location of the vehicle's suspension components.
This is referred to as NET BUILD. The result is no
required adjustment of camber and caster after the
vehicle is built or when servicing the suspension
components. Thus, when performing a wheel align-
ment, caster and camber are not normally considered
adjustable angles. Camber and caster should be
checked to ensure they meet vehicle specifications.
If front camber is found not to meet alignment
specifications, it can be adjusted using an available
camber adjustment bolt package. Before installing a
camber adjustment bolt package on a vehicle found
to be outside the specifications, inspect the suspen-
sion components for any signs of damage or bending.
RSWHEEL ALIGNMENT2-51
WHEEL ALIGNMENT (Continued)
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CAUTION: Do not attempt to adjust the vehicles
wheel alignment by heating, bending or by perform-
ing any other modification to the vehicle's front
suspension components or body.
If camber readings are not within specifications,
use the following procedure to install the front cam-
ber adjustment bolt package and then adjust front
camber.
CAMBER ADJUSTMENT BOLT PACKAGE INSTALLATION
The camber adjustment bolt package contains 2
flange bolts, 2 cam bolts, 2 dog bone washers, and 4
nuts. This package services both sides of the vehicle.
Use the package to attach the strut clevis bracket to
the steering knuckle after the strut clevis bracket
has been modified. To install and adjust the camber
adjustment bolt package, follow the procedure below.
(1) Raise the vehicle until its tires are not support-
ing the weight of the vehicle.
(2) Remove the front tire and wheel assemblies.
CAUTION: When removing the steering knuckle
from the strut clevis bracket, do not put a strain on
the brake flex hose. Also, do not let the weight of
the steering knuckle assembly be supported by the
brake flex hose when removed from the strut
assembly. If necessary use a wire hanger to sup-
port the steering knuckle assembly or if required
remove the brake flex hose from the caliper assem-
bly.
CAUTION: The knuckle to strut assembly attaching
bolt shanks are serrated and must not be turned
during removal. Remove the nuts while holding the
bolts stationary.
(3) Remove the top and bottom, strut clevis
bracket to steering knuckle attaching bolts (Fig.
7)and discard. Separate the steering knuckle from
the strut clevis bracket and position steering knuckle
so it is out of the way of the strut.
CAUTION: When slotting the bottom mounting hole
on the strut clevis bracket, do not enlarge the hole
beyond the indentations on the sides of the strut
clevis bracket (Fig. 8).
(4) Using an appropriate grinder and grinding
wheel, slot the bottom hole in both sides of the strut
clevis bracket (Fig. 8).
CAUTION: After slotting the strut clevis bracket
hole, do not install the original attaching bolts when
assembling the steering knuckle to the strut assem-
bly. Only the flange bolts, cam bolts, and dog bone
washers from the service package must be used toattach the steering knuckle to the strut after the
mounting hole is slotted.
NOTE: The strut clevis-to-knuckle bolts are installed
differently on each side of the vehicle. Left-hand-
side bolts are installed from vehicle rear to front
(Fig. 9). Right-hand-side bolts are installed from
vehicle front to rear.
Fig. 7 Clevis Bracket To Steering Knuckle Attaching
Bolts
1 - STRUT CLEVIS BRACKET
2 - ATTACHING BOLTS
3 - TIE ROD END
4 - ROTOR
5 - STEERING KNUCKLE
Fig. 8 Strut Clevis Bracket Bolt Hole Grinding Area
1 - UPPER STRUT TO STEERING KNUCKLE ATTACHING HOLE
2 - CAMBER ADJUSTMENT SLOT INDENTATION AREA ON
CLEVIS BRACKET
3 - LOWER STRUT TO STEERING KNUCKLE ATTACHING HOLE
4 - STRUT CLEVIS BRACKET
2 - 52 WHEEL ALIGNMENTRS
WHEEL ALIGNMENT (Continued)
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(3) Tighten tie rod jam nuts (Fig. 12) to 75 N´m
(55 ft. lbs.) torque.
(4) Adjust steering gear to tie rod boots at the
inner tie rod.
(5) Remove steering wheel clamp.
(6) Remove the alignment equipment.
(7) Road test the vehicle to verify the steering
wheel is straight and the vehicle does not wander or
pull.
STANDARD PROCEDURE - CURB HEIGHT
MEASUREMENT
The wheel alignment is to be checked and all align-
ment adjustments made with the vehicle at its
required curb height specification.
Vehicle height is to be checked with the vehicle on
a flat, level surface, preferably a vehicle alignment
rack. The tires are to be inflated to the recommended
pressure. All tires are to be the same size as stan-
dard equipment. Vehicle height is checked with the
fuel tank full of fuel, and no passenger or luggage
compartment load.
Vehicle height is not adjustable. If the measure-
ment is not within specifications, inspect the vehicle
for bent or weak suspension components. Compare
the parts tag on the suspect coil spring(s) to the
parts book and the vehicle sales code, checking for a
match. Once removed from the vehicle, compare the
coil spring height to a correct new or known good coil
spring. The heights should vary if the suspect spring
is weak.
(1) Measure from the inboard edge of the wheel
opening fender lip directly above the wheel center
(spindle), to the floor or alignment rack surface.
(2) When measuring, the maximum left-to-right
differential is not to exceed 12.5 mm (0.5 in.).
(3) Compare the measurements to the specifica-
tions listed in the following Curb Height Specifica-
tions charts.
CURB HEIGHT SPECIFICATIONS
TIRE SALES CODE/TIRE SIZE FRONT REAR
ALL755mm 11mm
29.72 in.   0.43 in770mm 11mm
30.31 in.   0.43 in.
Fig. 12 Front Wheel Toe Adjustment
1 - INNER TIE ROD SERRATION
2 - OUTER TIE ROD JAM NUT
3 - OUTER TIE ROD END
4 - INNER TIE ROD
5 - STEERING KNUCKLE
2 - 54 WHEEL ALIGNMENTRS
WHEEL ALIGNMENT (Continued)
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SHUDDER OR VIBRATION DURING ACCELERATION
This problem could be a result of:
²A worn or damaged half shaft inner tripod joint.
²A sticking tripod joint spider assembly (inner tri-
pod joint only).
²Improper wheel alignment. (Refer to 2 - SUS-
PENSION/WHEEL ALIGNMENT - STANDARD
PROCEDURE)
VIBRATION AT HIGHWAY SPEEDS
This problem could be a result of:
²Foreign material (mud, etc.) packed on the back-
side of the wheel(s).
²Out of balance tires or wheels. (Refer to 22 -
TIRES/WHEELS - STANDARD PROCEDURE)
²Improper tire and/or wheel runout. (Refer to 22 -
TIRES/WHEELS - DIAGNOSIS AND TESTING)
REMOVAL
(1) Raise vehicle.
(2) Remove the cotter pin and nut lock (Fig. 2)
from the end of the half shaft.
(3) Remove the wheel and tire assembly from the
vehicle. (Refer to 22 - TIRES/WHEELS - REMOVAL)
(4) Remove the wave washer (Fig. 3) from the end
of the half shaft.(5) With the vehicle's brakes applied to keep hub
from turning,loosen and removethe half shaft
nut.
(6) Remove the two front disc brake caliper
adapter to steering knuckle attaching bolts (Fig. 4).
Fig. 1 Unequal Length Half Shaft System
1 - STUB AXLE 8 - OUTER C/V JOINT
2 - OUTER C/V JOINT 9 - RIGHT HALFSHAFT
3 - OUTER C/V JOINT BOOT 10 - INNER TRIPOD JOINT BOOT
4 - TUNED RUBBER DAMPER WEIGHT 11 - INNER TRIPOD JOINT
5 - INTERCONNECTING SHAFT 12 - INNER TRIPOD JOINT
6 - OUTER C/V JOINT BOOT 13 - INNER TRIPOD JOINT BOOT
7 - STUB AXLE 14 - INTERCONNECTING SHAFT LEFT HALFSHAFT
Fig. 2 Half Shaft Retaining Nut
1 - HUB/BEARING
2 - NUT LOCK
3 - COTTER PIN
4 - STUB AXLE
3 - 2 HALF SHAFT - FRONTRS
HALF SHAFT - FRONT (Continued)
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HALF SHAFT - REAR
TABLE OF CONTENTS
page page
HALF SHAFT - REAR
DESCRIPTION.........................13
DIAGNOSIS AND TESTING - HALF SHAFT....13
REMOVAL.............................13
INSTALLATION.........................14SPECIFICATIONS - HALF SHAFT - FRONT . . . 15
CV BOOT - INNER/OUTER
REMOVAL.............................15
INSTALLATION.........................17
HALF SHAFT - REAR
DESCRIPTION
The inner and outer joints of both half shaft
assemblies are tripod joints. The tripod joints are
true constant velocity (CV) joint assemblies, which
allow for the changes in half shaft length through
the jounce and rebound travel of the rear suspension.
On vehicles equipped with ABS brakes, the outer
CV joint is equipped with a tone wheel used to deter-
mine vehicle speed for ABS brake operation.
The inner tripod joint of both half shafts is bolted
rear differential assembly's output flanges. The outer
CV joint has a stub shaft that is splined into the
wheel hub and retained by a steel hub nut.
DIAGNOSIS AND TESTING - HALF SHAFT
VEHICLE INSPECTION
(1) Check for grease in the vicinity of the inboard
tripod joint and outboard CV joint; this is a sign of
inner or outer joint seal boot or seal boot clamp dam-
age.
NOISE AND/OR VIBRATION IN TURNS
A clicking noise and/or a vibration in turns could
be caused by one of the following conditions:
²Damaged outer CV 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.
²Noise may also be caused by another component
of the vehicle coming in contact with the half shafts.
CLUNKING NOISE DURING ACCELERATION
This noise may be a result of one of the following
conditions:
²A torn seal boot on the inner or outer joint of the
half shaft assembly.
²A loose or missing clamp on the inner or outer
joint of the half shaft assembly.
²A damaged or worn half shaft CV joint.
SHUDDER OR VIBRATION DURING ACCELERATION
This problem could be a result of:
²A worn or damaged half shaft inner tripod joint.
²A sticking tripod joint spider assembly (inner tri-
pod joint only).
²Improper wheel alignment. (Refer to 2 - SUS-
PENSION/WHEEL ALIGNMENT - STANDARD
PROCEDURE)
VIBRATION AT HIGHWAY SPEEDS
This problem could be a result of:
²Foreign material (mud, etc.) packed on the back-
side of the wheel(s).
²Out of balance tires or wheels. (Refer to 22 -
TIRES/WHEELS - STANDARD PROCEDURE)
²Improper tire and/or wheel runout. (Refer to 22 -
TIRES/WHEELS - DIAGNOSIS AND TESTING)
REMOVAL
(1) Lift vehicle on hoist so that the wheels hang
freely.
(2) Remove rear wheel.
(3) Remove cotter pin, nut lock, and spring washer
(Fig. 1).
Fig. 1 Cotter Pin, Nut Lock, And Spring Washer
1 - HUB NUT
2 - NUT LOCK
3 - COTTER PIN
4 - SPRING WASHER
RSHALF SHAFT - REAR3-13
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front and rear drive units. The unit is totally sealed
and partially filled with silicone fluid. There is no
adjustment, maintenance or fluid checks required
during the life of the unit.
The overrunning clutch allows the rear wheels to
overrun the front wheels during a rapid front wheel
lock braking maneuver. The overrunning action pre-
vents any feed-back of front wheel braking torque to
the rear wheels. It also allows the braking system to
control the braking behavior as a two wheel drive
(2WD) vehicle.
The overrunning clutch housing has a separate oil
sump and is filled independently from the differen-
tial. The fill plug is located on the side of the over-
running clutch case. When filling the overrunning
clutch with lubricant use MopartATF+4 (Automatic
Transmission FluidÐType 9602) or equivalent.
The differential assembly contains a conventional
open differential with hypoid ring gear and pinion
gear set. The hypoid gears are lubricated by SAE
80W-90 gear lubricant.DIAGNOSIS AND TESTING
DIAGNOSIS AND TESTING - REAR DRIVELINE
MODULE NOISE
Different sources can be the cause of noise that the
rear driveline module assembly is suspected of mak-
ing. Refer to the following causes for noise diagnosis.
DRIVELINE MODULE ASSEMBLY NOISE
The most important part of driveline module ser-
vice is properly identifying the cause of failures and
noise complaints. The cause of most driveline module
failures is relatively easy to identify. The cause of
driveline module noise is more difficult to identify.
If vehicle noise becomes intolerable, an effort
should be made to isolate the noise. Many noises that
are reported as coming from the driveline module
may actually originate at other sources. For example:
²Tires
²Road surfaces
²Wheel bearings
Fig. 1 AWD Driveline Module Assembly
1 - TORQUE ARM 8 - WASHER 15 - PLUG-OVERRUNNING CLUTCH
HOUSING DRAIN
2 - INPUT FLANGE 9 - BI-DIRECTIONAL OVERRUNNING
CLUTCH (BOC)16 - SNAP RING
3 - FLANGE NUT 10 - VISCOUS COUPLER 17 - BEARING
4 - WASHER 11 - SHIM (SELECT) 18 - OVERRUNING CLUTCH HOUSING
5 - SHIELD 12 - O-RING 19 - SEAL-INPUT FLANGE
6 - VENT 13 - DIFFERENTIAL ASSEMBLY
7 - O-RING 14 - PLUG-DIFFERENTIAL FILL
3 - 24 REAR DRIVELINE MODULERS
REAR DRIVELINE MODULE (Continued)
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²Engine
²Transmission
²Exhaust
²Propeller shaft (vibration)
²Vehicle body (drumming)
Driveline module noises are normally divided into
two categories: gear noise or bearing noise. A thor-
ough and careful inspection should be completed to
determine the actual source of the noise before
replacing the driveline module.
The rubber mounting bushings help to dampen-out
driveline module noise when properly installed.
Inspect to confirm that no metal contact exists
between the driveline module case and the body. The
complete isolation of noise to one area requires
expertise and experience. Identifying certain types of
vehicle noise baffles even the most capable techni-
cians. Often such practices as:
²Increase tire inflation pressure to eliminate tire
noise.
²Listen for noise at varying speeds with different
driveline load conditions
²Swerving the vehicle from left to right to detect
wheel bearing noise.
All driveline module assemblies produce noise to a
certain extent. Slight carrier noise that is noticeable
only at certain speeds or isolated situations should be
considered normal. Carrier noise tends to peak at a
variety of vehicle speeds. Noise isNOT ALWAYSan
indication of a problem within the carrier.
TIRE NOISE
Tire noise is often mistaken for driveline module
noise. Tires that are unbalanced, worn unevenly or
are worn in a saw-tooth manner are usually noisy.
They often produce a noise that appears to originate
in the driveline module.
Tire noise changes with different road surfaces, but
driveline module noise does not. Inflate all four tires
with approximately 20 psi (138 kPa) more than the
recommended inflation pressure (for test purposes
only). This will alter noise caused by tires, but will
not affect noise caused by the differential. Rear axle
noise usually ceases when coasting at speeds less
than 30 mph (48 km/h); however, tire noise contin-
ues, but at a lower frequency, as the speed is
reduced.
After test has been completed lower tire pressure
back to recommended pressure.
GEAR NOISE (DRIVE PINION AND RING GEAR)
Abnormal gear noise is rare and is usually caused
by scoring on the ring gear and drive pinion. Scoring
is the result of insufficient or incorrect lubricant in
the carrier housing.Abnormal gear noise can be easily recognized. It
produces a cycling tone that will be very pronounced
within a given speed range. The noise can occur dur-
ing one or more of the following drive conditions:
²Drive
²Road load
²Float
²Coast
Abnormal gear noise usually tends to peak within
a narrow vehicle speed range or ranges. It is usually
more pronounced between 30 to 40 mph (48 to 64
km/h) and 50 to 60 mph (80 to 96 km/h). When objec-
tionable gear noise occurs, note the driving condi-
tions and the speed range.
BEARING NOISE (DRIVE PINION AND
DIFFERENTIAL)
Defective bearings produce a rough growl that is
constant in pitch and varies with the speed of vehi-
cle. Being aware of this will enable a technician to
separate bearing noise from gear noise.
Drive pinion bearing noise that results from defec-
tive or damaged bearings can usually be identified by
its constant, rough sound. Drive pinion front bearing
is usually more pronounced during a coast condition.
Drive pinion rear bearing noise is more pronounced
during a drive condition. The drive pinion bearings
are rotating at a higher rate of speed than either the
differential side bearings or the axle shaft bearing.
Differential side bearing noise will usually produce
a constant, rough sound. The sound is much lower in
frequency than the noise caused by drive pinion bear-
ings.
Bearing noise can best be detected by road testing
the vehicle on a smooth road (black top). However, it
is easy to mistake tire noise for bearing noise. If a
doubt exists, the tire treads should be examined for
irregularities that often causes a noise that resem-
bles bearing noise.
ENGINE AND TRANSMISSION NOISE
Sometimes noise that appears to be in the driv-
eline module assembly is actually caused by the
engine or the transmission. To identify the true
source of the noise, note the approximate vehicle
speed and/or RPM when the noise is most noticeable.
Stop the vehicle next to a flat brick or cement wall
(this will help reflect the sound). Place the transaxle
inNEUTRAL. Accelerate the engine slowly up
through the engine speed that matches the vehicle
speed noted when the noise occurred. If the same
noise is produced, it usually indicates that the noise
is being caused by the engine or transaxle.
RSREAR DRIVELINE MODULE3-25
REAR DRIVELINE MODULE (Continued)
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