2001 DODGE TOWN AND COUNTRY manual transmission

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 - 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:
Fig. 1 AWD Driveline Module Assembly
1 - TORQUE ARM
2 - INPUT FLANGE
3 - FLANGE NUT
4 - WASHER
5 - SHIELD
6 - VENT
7 - O-RING
8 - WASHER
9 - BI-DIRECTIONAL OVERRUNNING CLUTCH (BOC)
10 - VISCOUS COUPLER11 - SHIM (SELECT)
12 - O-RING
13 - DIFFERENTIAL ASSEMBLY
14 - PLUG-DIFFERENTIAL FILL
15 - PLUG-OVERRUNNING CLUTCH HOUSING DRAIN
16 - SNAP RING
17 - BEARING
18 - OVERRUNING CLUTCH HOUSING
19 - SEAL-INPUT FLANGE
RSREAR DRIVELINE MODULE3-27
REAR DRIVELINE MODULE (Continued)
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²Tires
²Road surfaces
²Wheel bearings
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. Scoringis 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.
3 - 28 REAR DRIVELINE MODULERS
REAR DRIVELINE MODULE (Continued)
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DIAGNOSIS AND TESTING - REAR DRIVELINE
MODULE OPERATION
Driveline module operation requires relatively
straight-forward diagnosis. Refer to the following
chart:
DRIVELINE MODULE DIAGNOSIS CHART
CONDITION POSSIBLE CAUSES CORRECTION
Rear wheels not
overrunning1) Bi-directional overrunning clutch
failure1) Replace overrunning clutch
components as required
No AWD in forward or
reverse directions, propeller
shaft turning1) Bi-directional overrunning clutch
failure1) Replace overrunning clutch
components as required
2) Viscous coupling failure 2) Replace viscous coupling
3) Rear differential failure 3) Replace the rear differential
assembly
No AWD in forward or
reverse directions, propeller
shaft not turning1) Power transfer unit failure. 1) Replace power transfer unit
components as necessary
Vibration at all speeds,
continuous torque transfer1) Mis-matched tires, worn tires on
front axle.1) Replace worn or incorrect
(mis-matched) tires with same
make and size
REMOVAL
(1) Raise vehicle on hoist.
(2) Drain fluid from overrunning clutch housing
and/or differential assembly if necessary.
(3) Remove propeller shaft. (Refer to 3 - DIFFER-
ENTIAL & DRIVELINE/PROPELLER SHAFT -
REMOVAL)
(4) Disconnect left and right rear halfshafts from
output flanges (Fig. 2).(5) Remove torque arm mount to body bolts.
(6) Position transmission jack to driveline module
assembly and secure assembly to jack.
(7) Remove two driveline module-to-body bolts
(Fig. 3).
(8) Lower driveline module from vehicle and
remove from jack.
Fig. 2 Half Shaft Mounting Bolts
1 - SHAFT
2 - FLANGE
Fig. 3 Rear Drive Line Module Assembly Mounting
Bolts
1 - DRIVELINE MODULE RETAINING BOLT (2)
2 - RUBBER ISOLATOR
3 - WASHER
RSREAR DRIVELINE MODULE3-29
REAR DRIVELINE MODULE (Continued)
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INSTALLATION
(1) Install rear driveline module assembly to
transmission jack and secure.
(2) Raise rear driveline module into position and
install and torque mounting bolts (Fig. 26) to 54 N´m
(40 ft. lbs.).
(3) Remove transmission jack.
(4) Install and torque torque arm mount-to-body
bolts to 54 N´m (40 ft. lbs.).
(5) Install halfshafts to differential output flanges
and torque bolts (Fig. 27) to 61 N´m (45 ft. lbs.).
(6) Install propeller shaft. (Refer to 3 - DIFFER-
ENTIAL & DRIVELINE/PROPELLER SHAFT -
INSTALLATION)
(7) Lower vehicle.
Fig. 25 Torque Arm Fasteners
1 - TORQUE ARM ASSEMBLY
2 - BOLT (SIX)
Fig. 26 Rear Drive Line Module Assembly Rear
Mounting Bolts
1 - DRIVELINE MODULE RETAINING BOLT (2)
2 - RUBBER ISOLATOR
3 - WASHER
Fig. 27 Half Shaft Mounting Bolts
1 - SHAFT
2 - FLANGE
3 - 36 REAR DRIVELINE MODULERS
REAR DRIVELINE MODULE (Continued)
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SPECIFICATIONS
SPECIFICATIONS - REAR DRIVELINE MODULE
TORQUE SPECIFICATIONS
DESCRIPTION N´m Ft. Lbs. In. Lbs.
Bolt, Driveline Module-to-Body 54 40 Ð
Bolt, Halfshaft-to-Ouput Flange 61 45 Ð
Bolt, Overrunning Clutch Housing-to-
Differential60 44 Ð
Bolt, Torque Arm-to-Differential Assembly 60 44 Ð
Bolt, Torque Arm Mount-to-Body 54 40 Ð
Nut, Input Flange 135 100 Ð
Plug, Differential Drain/Fill 35 26 Ð
Plug, Overrunning Clutch Housing Drain/Fill 30 22 Ð
Vent, Differential/Overrunning Clutch
Housing12 Ð 110
SPECIAL TOOLS
SPECIAL TOOLS
BI-DIRECTIONAL
OVERRUNNING CLUTCH
DESCRIPTION
The bi-directional overrunning clutch (BOC) (Fig.
28) works as a mechanical disconnect between the
front and rear axles, preventing torque from being
transferred from the rear axle to the front. The BOC
is a simply an overrunning clutch which works in
both clockwise and counter-clockwise rotations. This
means that when the output (the rear axle) is rotat-
ing faster in one direction than the input (front axle),
there is no torque transmission. But when the input
speed is equal to the output speed, the unit becomes
locked. The BOC provides significant benefits regard-
ing braking stability, handling, and driveline durabil-
ity. Disconnecting the front and the rear driveline
during braking helps to maintain the braking stabil-
ity of an AWD vehicle. In an ABS/braking event, the
locking of the rear wheels must be avoided for stabil-
ity reasons. Therefore brake systems are designed to
Tool 6958
Tool 8493
Tool 8802
RSREAR DRIVELINE MODULE3-37
REAR DRIVELINE MODULE (Continued)
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lock the front wheels first. Any torque transfer from
the rear axle to the front axle disturbs the ABS/brak-
ing system and causes potential instabilities on a
slippery surface. The BOC de-couples the rear driv-
eline as soon the rear wheels begin to spin faster
than the front wheels (front wheels locked) in order
to provide increased braking stability. Furthermore
the BOC also reduces the likelihood of throttle off
over-steer during cornering. In a throttle off maneu-
ver, the BOC once again de-couples the rear driveline
forcing all the engine brake torque to the front
wheels. This eliminates the chance of lateral slip on
the rear axle and increases it on the front. The vehi-
cle will therefore tend to understeer, a situation
which is considered easier to manage in most circum-
stances. During this maneuver, and during the ABS
braking event, the BOC does not transmit torque
through to the rear wheels. The rear driveline mod-
ule, with the BOC, will perform the same as a front
wheel drive vehicle during these events. The gear
ratio offset between the front and rear differentials
force the BOC into the overrunning mode most of the
time. This allows BOC to significantly reduce the
rolling resistance of the vehicle, which improves fuel
consumption, allows the downsizing of the driveline
components, and prevents the PTU and propshaft
joints from overheating.
OPERATION
In order to achieve all-wheel drive operation in
reverse, the overrunning clutch locking functional
direction must be reversible. The bi-directional over-
running clutch (BOC) changes the operational mode
direction depending on the propeller shaft direction.
The propeller shaft rotates in the clockwise (when
viewed from the front) direction when the vehicle is
moving forward, which indexes the BOC to the for-
ward overrunning position. When the vehicle is in
reverse, the propeller shaft will rotate counter-clock-
wise and index the BOC to the reverse overrunning
position.
The BOC acts as a mechanical stator. It is active
(transmitting torque), or it is not active and in over-
running mode (not transmitting torque). This ªall or
nothingº approach to torque transfer would cause a
sudden application of all available power to the rear
wheels, which is not desirable. Therefore it is run in
series with a viscous coupler to smooth, dampen, and
limit the transmission of torque to the rear axle and
to prevent a step style torque input to the rear axle.
STEADY STATE, LOW TO MODERATE SPEED, NO
FRONT WHEEL SLIP, FORWARD DIRECTION
During normal driving conditions, (no wheel slip),
the inner shaft (front axle) and outer race (viscous
coupler) are running at different speeds due to the
different gear ratios between the front and rear dif-
ferentials. In this condition, the outer race is always
spinning faster (overdriving between 5-32 rpm) than
the inner shaft. When the BOC (Fig. 29) is running
under these conditions, at low vehicle speeds the
drag shoes and the cage keep the rollers up on the
left side (forward side) of the inner shaft flats. This is
what is known as ªoverrunning mode.º Notice that
when the clutch is in overrunning mode, the rollers
are spinning clockwise and with the outer race, thus
no torque is being transferred.
NOTE: Low speed, forward and reverse operation is
identical, just in opposite directions. (Fig. 29)
shows forward direction in reverse the rollers are
on the other side of the flats due to a reversal of
the cage force.
TRANSIENT CONDITION (BOC LOCKED), FRONT
WHEEL SLIP, FORWARD DIRECTION
When the front wheels lose traction and begin to
slip, the propeller shaft and rear axle pinion speed
difference decreases to zero. At this point the input
shaft (cam) becomes the driving member of the BOC
(Fig. 30), compressing the rollers against the outer
race. This locks the input shaft with the outer race
and transmits torque to the housing of the viscous
coupler, that in turn transmits torque to the rear
axle pinion. It should also be noted that when the
device is locked, the inner shaft and the outer race
are rotating at the same speed. The rollers are
pinched at this point and will stay locked until a
torque reversal (no front wheel slip) occurs. When
locked, the viscous coupler slips during the torque
transfer and the amount of torque transferred is
dependent on the coupling characteristic and the
amount of front wheel slip.
3 - 38 REAR DRIVELINE MODULERS
BI-DIRECTIONAL OVERRUNNING CLUTCH (Continued)
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(3) Remove overrunning clutch housing drain plug
and drain fluid (Fig. 43).
(4) Install the drain plug and torque to 30 N´m (22
ft. lbs.).
(5) Re-position the drain pan under the overrun-
ning clutch housing fill plug.
(6) Remove fill plug (Fig. 44).
(7) Using a suction gun (Fig. 45), add 0.58 L (1.22
pts.) of MopartATF+4 (Automatic Transmission Flu-
idÐType 9602).
(8)
Install fill plug and torque to 30 N´m (22 ft. lbs.).
VISCOUS COUPLER
DESCRIPTION
The heart of the all-wheel drive system is the inter-
axle viscous coupling and bi-directional overrunning
clutch. Under normal driving the vehicle retains pre-
dominantly front wheel drive characteristics. The all-
wheel drive takes effect when the front wheels start to
slip. Under normal level road, straight line driving,
100% of the torque is allocated to the front wheels.
The viscous coupler allows more torque to the rear
wheels in accordance with the amount of slippage at
the front wheels. The variable torque distribution is
automatic with no driver inputs required.
OPERATION
The viscous coupler (Fig. 46) is a housing nearly
filled with a high viscosity silicone liquid and thin
metal plates alternately splined to an inner and
outer drum. The viscous coupler provides torque in
the following modes:
²Shear mode (normal operation)
²Hump mode (locked mode)
The inner plates are slotted around the radius and
the outer plates have holes in them. In the shear
mode (normal operation), the plates are evenly
spaced and the torque is created by the shearing of
the plates through the fluid and 90-100% of the
torque is applied to the rear axle. During the shear
mode, a fluid flow pattern is created from this design
(holes and slots). This fluid flow causes high pressure
on each side of each pair of plates and low pressure
between each pair of plates.
Fig. 43 Overrunning Clutch Case Drain Plug
1 - OVERRUNNING CLUTCH HOUSING DRAIN PLUG
Fig. 44 Overrunning Clutch Housing Fill Plug
1 - OVERRUNNING CLUTCH HOUSING FILL PLUG
2 - FUEL TANK
Fig. 45 Filling Overrunning Clutch Case
1 - OVERRUNNING CLUTCH HOUSING FILL HOLE
2 - SUCTION GUN
RSREAR DRIVELINE MODULE3-45
FLUID (Continued)
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RED BRAKE WARNING INDICATOR LAMP
CONDITION POSSIBLE CAUSES CORRECTION
RED BRAKE WARNING
LAMP ON1. Parking brake lever not fully
released.1. Release parking brake lever.
2. Parking brake warning lamp
switch on parking brake lever.2. Inspect and replace switch as necessary.
3. Brake fluid level low in reservoir. 3. Fill reservoir. Check entire system for
leaks. Repair or replace as required.
4. Brake fluid level switch. 4. Disconnect switch wiring connector. If
lamp goes out, replace switch.
5. Mechanical instrument cluster
(MIC) problem.5. Refer to appropriate Diagnostic
information.
6. Amber ABS Warning Indicator
Lamp also illuminated.6. Refer to appropriate Diagnostic
information.
BRAKE NOISE
CONDITION POSSIBLE CAUSES CORRECTION
CLICK OR SQUAWK ON
PEDAL APPLICATION1. Brake lamp switch. 1. Replace switch.
2. Brake Transmission Shift Interlock
Linkage.2. Lubricate BTSI linkage.
3. Pedal pivot bushings 3. Lubricate pivot bushings. Replace if
necessary.
DISC BRAKE CHIRP 1. Excessive brake rotor runout. 1. Follow brake rotor diagnosis and testing.
Correct as necessary.
2. Lack of lubricant on brake caliper
slides.2. Lubricate brake caliper slides.
3. Caliper/shoes not fully seated. 3. Reseat caliper/shoes.
DISC BRAKE RATTLE OR
CLUNK1. Broken or missing anti-rattle
spring clips on shoes.1. Replace brake shoes.
2. Caliper guide pins/bolts loose. 2. Tighten guide pins/bolts.
DISC BRAKE SQUEAK AT
LOW SPEED (WHILE
APPLYING LIGHT BRAKE
PEDAL EFFORT)1. Brake shoe linings. 1. Replace brake shoes.
DRUM BRAKE CHIRP 1. Lack of lubricant on brake shoe
support plate where shoes ride.1. Lubricate shoe contact areas on brake
shoe support plates.
DRUM BRAKE CLUNK 1. Drum(s) have threaded machined
braking surface.1. Reface or replace drake drums as
necessary.
DRUM BRAKE HOWL OR
MOAN1. Lack of lubricant on brake shoe
support plate where shoes ride and
at the anchor.1. Lubricate shoe contact areas on brake
shoe support plates and at the anchor.
2. Rear brake shoes. 2. Replace rear brake shoes.
DRUM BRAKE SCRAPING
OR WHIRRING1. ABS wheel speed sensor or tone
wheel.1. Inspect, correct or replace faulty
component(s).
5 - 4 BRAKES - BASERS
BRAKES - BASE (Continued)
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