differential DODGE RAM 2001 Service Owner's Manual

DIFFERENTIAL
REMOVAL
(1) Raise and support vehicle.
(2) Remove lubricant fill hole plug from the differ-
ential housing cover.
(3) Remove differential housing cover and drain
the lubricant from the housing.
(4) Clean the housing cavity with a flushing oil,
light engine oil or lint free cloth.Do not use water,
steam, kerosene or gasoline for cleaning.
(5) Remove hub bearings and axle shafts.
(6) Note the installation reference letters stamped
on the bearing caps and housing machined sealing
surface (Fig. 37).
(7) Remove the differential bearing caps.
(8) Position Spreader W-129-B with the tool dowel
pins seated in the locating holes (Fig. 38).
(9) Install the hold down clamps and tighten the
spreader turnbuckle finger-tight.
(10) Install Pilot Stud C-3288-B to the left side of
the differential housing and attach dial indicator to
the pilot stud. Load the indicator plunger against the
opposite side of the housing (Fig. 38) and zero the
dial indicator.
(11) Spread the housing enough to remove the case
from the housing. Measure the distance with the dial
indicator (Fig. 38).
CAUTION: Do not spread over 0.50 mm (0.020 in). If
the housing is over-spread it could be distorted or
damaged.
(12) Remove the dial indicator.(13) Pry the differential case loose from the hous-
ing. To prevent damage, pivot on housing with the
end of the pry bar against spreader (Fig. 39).
(14) Remove the case from housing.
(15) Remove and tag bearing cups to indicate their
original location.
DISASSEMBLY
(1) Remove roll-pin holding mate shaft in housing.
(2) Remove pinion gear mate shaft (Fig. 40).
Fig. 36 Pinion Shaft Nut
1 - PINION FLANGE
2 - HOLDING TOOL 6719
3 - AXLE HOUSING
Fig. 37 Bearing Cap Reference
1 - REFERENCE LETTERS
2 - REFERENCE LETTERS
Fig. 38 Spread Differential Housing
1 - HOUSING SPREADER W-129B
2 - DIAL INDICATOR C-3339
3 - DIFFERENTIAL
4 - AXLE HOUSING
5 - GUIDE PIN C-3288±B
3 - 36 FRONT AXLE - 216FBIBR/BE
PINION SEAL (Continued)

(3) Rotate the differential side gears and remove
the pinion mate gears and thrust washers (Fig. 41).
(4) Remove the differential side gears and thrust
washers.ASSEMBLY
(1) Install the differential side gears and thrust
washers.
(2) Install the pinion mate gears and thrust wash-
ers.
(3) Install the pinion gear mate shaft.
(4) Align the hole in the pinion gear mate shaft
with the hole in the differential case.
(5) Install and seat the pinion mate shaft roll-pin
in the differential case and mate shaft with a punch
and hammer (Fig. 42). Peen the edge of the roll-pin
hole in the differential case slightly in two places,
180É apart.
(6) Lubricate all differential components with
hypoid gear lubricant.
INSTALLATION
NOTE: If replacement differential bearings or differ-
ential case are being installed, differential side
bearing shim requirements may change. Refer to
Adjustments (Differential Bearing Preload and Gear
Backlash) procedures to determine proper shim
selection.
(1) Position Spreader W-129-B with the tool dowel
pins seated in the locating holes. Install the hold
down clamps and tighten the tool turnbuckle finger-
tight.
Fig. 39 Differential Removal
1 - DIFFERENTIAL
2-PRYBAR
Fig. 40 Pinion Mate Shaft
1 - PINION MATE GEAR
2 - PINION MATE SHAFT
3 - SIDE GEAR
4 - DRIFT
Fig. 41 Pinion Mate/Side Gear
1 - THRUST WASHER
2 - SIDE GEAR
3 - PINION MATE GEAR
BR/BEFRONT AXLE - 216FBI 3 - 37
DIFFERENTIAL (Continued)

(2) Install a Pilot Stud C-3288-B at the left side of
the differential housing and attach dial indicator to
the pilot stud. Load the indicator plunger against the
opposite side of the housing and zero the dial indica-
tor.
(3) Spread the housing enough to install the case
in the housing. Measure the distance with the dial
indicator.
CAUTION: Do not spread over 0.50 mm (0.020 in). If
the housing is over-spread, it could be distorted or
damaged.
(4) Remove the dial indicator.
(5) Install differential into the housing. Tap the
differential case with a rawhide/rubber hammer to
ensure the bearings are seated in housing (Fig. 43).
(6) Remove the spreader.
(7) Install bearing caps in their original locations
(Fig. 44) and tighten bearing cap bolts to 109 N´m
(80 ft. lbs.).
(8) Install axle shafts.
(9) Install the hub bearings.
(10) Apply a bead of Mopar Silicone Rubber Seal-
ant or equivalent to the housing cover (Fig. 45).
Install the housing cover within 5 minutes
after applying the sealant.(11) Install the cover and any identification tag.
Tighten the cover bolts in a criss-cross pattern to 47
N´m (35 ft. lbs.).
(12) Refill the differential with Mopar Hypoid
Gear Lubricant or equivalent to bottom of the fill
plug hole. Refer to the Lubricant Specifications for
correct quantity and type.
(13) Install the fill hole plug and tighten to 34 N´m
(25 ft. lbs.).
(14) Remove support and lower vehicle.
Fig. 42 Pinion Mate Shaft Roll-Pin
1 - PUNCH
2 - PINION MATE SHAFT
3 - MATE SHAFT LOCKPIN
Fig. 43 Differential Case
1 - RAWHIDE HAMMER
Fig. 44 Bearing Cap Reference
1 - REFERENCE LETTERS
2 - REFERENCE LETTERS
3 - 38 FRONT AXLE - 216FBIBR/BE
DIFFERENTIAL (Continued)

DIFFERENTIAL CASE
BEARINGS
REMOVAL
(1) Remove differential case from axle housing.
(2) Remove differential bearings from the case
with Puller/Press C-293-PA, Adapters C-293-18 and
Plug C-293-3 (Fig. 46).
(3) Remove differential preload shims from differ-
ential case hubs and tag shims to indicate location.
INSTALLATION
(1) Install differential preload shims on differential
case in their original locations.
(2) Install differential bearings with Installer
D-156 with Handle C-4171 (Fig. 47).
(3) Install differential into the housing.
Fig. 45 Differential Cover
1 - SEALANT SURFACE
2 - SEALANT
3 - SEALANT THICKNESS
Fig. 46 Differential Bearing Puller
1 - ADAPTERS
2 - BEARING
3 - DIFFERENTIAL
4 - PLUG
5 - PULLER
BR/BEFRONT AXLE - 216FBI 3 - 39
DIFFERENTIAL (Continued)

PINION GEAR/RING GEAR
REMOVAL
NOTE: The ring and pinion gears are serviced as a
matched set. Never replace one gear without replac-
ing the other gear.
(1) Raise and support the vehcile.
(2) Mark pinion yoke and propeller shaft for
installation reference.
(3) Disconnect propeller shaft from pinion yoke
and tie propeller shaft to underbody.
(4) Remove differential from the housing.
(5) Secure differential case in a vise with soft
metal jaw.
(6) Remove ring gear bolts from the differential
case.
(7) Drive ring gear off the differential case with a
rawhide hammer (Fig. 48).
(8) Hold yoke with Holder 6719A and remove pin-
ion nut and washer.
(9) Remove pinion yoke from the pinion shaft with
Puller C-452 and Flange Wrench C-3281 (Fig. 49).
(10) Remove pinion gear from housing (Fig. 50).
(11) Remove pinion seal with a pry bar or slide
hammer mounted screw.(12) Remove front pinion bearing and oil slinger.
(13) Remove front pinion bearing cup with
Remover D-147 and Handle C-4171 (Fig. 51).
(14) Remove rear bearing cup (Fig. 52) with
Remover D-149 and Handle C-4171.
(15) Remove collapsible preload spacer from pinion
shaft (Fig. 53).
(16) Remove rear pinion bearing with Puller
C-293-PA and Adapters C-293-40 (Fig. 54).
(17) Remove pinion depth shims from pinion shaft
and record thickness.
Fig. 47 Differential Bearing Installer
1 - HANDLE
2 - DIFFERENTIAL
3 - BEARING
4 - INSTALLER
Fig. 48 Ring Gear
1 - CASE
2 - RING GEAR
3- HAMMER
Fig. 49 Pinion Yoke
1 - YOKE HOLDER
2 - YOKE
3 - YOKE PULLER
3 - 40 FRONT AXLE - 216FBIBR/BE
DIFFERENTIAL CASE BEARINGS (Continued)

(11) Install yoke washer and anewnut on the
pinion gear. Tighten the nut to 258 N´m (190 ft. lbs.)
minimum.Do not over-tighten.Maximum torque is
393 N´m (290 ft. lbs.).
CAUTION: Never loosen pinion gear nut to decrease
pinion gear bearing preload torque and never
exceed specified preload torque. If preload torque
is exceeded a new collapsible spacer must be
installed.
(12) Use Yoke Holder 6719A to hold the yoke (Fig.
61) and tighten the nut in 6.8 N´m (5 ft. lbs.) until
the rotating torque is achieved. Measure the preload
torque frequently to avoid over-tightening the nut.
(13) Check bearing preload torque with an inch
pound torque wrench (Fig. 62). The torque necessary
to rotate the pinion gear should be:
²Original Bearings: 1 to 3 N´m (10 to 20 in. lbs.).
²New Bearings: 2 to 5 N´m (15 to 35 in. lbs.).
(14) Invert differential case in a vise and start two
ring gear bolts. This will provide case-to-ring gear
bolt hole alignment.
(15) Installnewring gear bolts and alternately
tighten to 108 N´m (80 ft. lbs.). (Fig. 63).
CAUTION: Do not reuse the bolts that held the ring
gear to the differential case. The bolts can fracture
causing extensive damage.
(16) Install differential in axle housing and verify
gear mesh and contact pattern. Refer to Adjustments
(Gear Contact Pattern).
(17) Install differential cover and fill with lubri-
cant.(18) Install propeller shaft with reference marks
aligned.
(19) Remove support and lower vehicle.
Fig. 61 Tightening Pinion Nut
1 - PINION FLANGE
2 - YOKE HOLDING
3 - DIFFERENTIAL HOUSING
Fig. 62 Pinion Rotating Torque
1 - PINION YOKE
2 - INCH POUND TORQUE WRENCH
Fig. 63 Ring Gear Bolt
1 - TORQUE WRENCH
2 - RING GEAR BOLT
3 - RING GEAR
4 - CASE
3 - 44 FRONT AXLE - 216FBIBR/BE
PINION GEAR/RING GEAR (Continued)

FRONT AXLE - 248FBI
TABLE OF CONTENTS
page page
FRONT AXLE - 248FBI
DESCRIPTION...........................45
OPERATION.............................45
DIAGNOSIS AND TESTING.................46
AXLE................................46
REMOVAL..............................50
INSTALLATION...........................50
ADJUSTMENTS..........................50
SPECIFICATIONS........................58
SPECIAL TOOLS.........................58
AXLE SHAFTS
REMOVAL..............................60
INSTALLATION...........................60
AXLE SHAFTS - INTERMEDIATE
REMOVAL..............................60
INSTALLATION...........................61
AXLE SHAFT SEALS
REMOVAL..............................61
INSTALLATION...........................61
AXLE VACUUM MOTOR
DESCRIPTION...........................62
OPERATION.............................62
DIAGNOSIS AND TESTING.................63VACUUM MOTOR.......................63
REMOVAL..............................65
DISASSEMBLY...........................65
ASSEMBLY.............................65
INSTALLATION...........................65
SINGLE CARDAN UNIVERSAL JOINTS
REMOVAL..............................65
INSTALLATION...........................66
PINION SEAL
REMOVAL..............................66
INSTALLATION...........................66
DIFFERENTIAL
REMOVAL..............................68
DISASSEMBLY...........................68
ASSEMBLY.............................69
INSTALLATION...........................69
DIFFERENTIAL CASE BEARINGS
REMOVAL..............................71
INSTALLATION...........................71
PINION GEAR/RING GEAR
REMOVAL..............................72
INSTALLATION...........................74
FRONT AXLE - 248FBI
DESCRIPTION
The housing for the 248 Front Beam-design Iron
(FBI) axle consists of an iron center casting with
tubes on each side. The tubes are pressed into and
welded to the differential housing.
The integral type housing, hypoid gear design has
the centerline of the pinion set below the centerline
of the ring gear.
The axle has a vent used to relieve internal pres-
sure caused by lubricant vaporization and internal
expansion.
The axles are equipped with semi-floating axle
shafts, meaning that loads are supported by the hub
bearings. The axle shafts are retained by nuts at the
hub bearings. The hub bearings are bolted to the
steering knuckle at the outboard end of the axle tube
yoke. The hub bearings are serviced as an assembly.
The axles are equipped with ABS brake sensors.
The sensors are attached to the knuckle assemblies
and the tone rings are pressed onto the axle shaft.
Use care when removing axle shafts as NOT to
damage the tone wheel or the sensor.The stamped steel cover provides a means for
inspection and servicing the differential.
The 248 FBI axle have the assembly part number
and gear ratio listed on a tag. The tag is attached to
the housing cover by one of the cover bolts. Build
date identification codes are stamped on the cover
side of a axle tube.
The differential case is a one-piece design. The dif-
ferential pinion mate shaft is retained with a roll
pin. Differential bearing preload and ring gear back-
lash is adjusted by the use of shims. The shims are
located between the differential bearing cones and
case. Pinion bearing preload is set and maintained by
the use of a collapsible spacer.
The axle differential covers can be used for identi-
fication of the axle (Fig. 1). A tag is also attached to
the cover.
OPERATION
The axle receives power from the transfer case
through the front propeller shaft. The front propeller
shaft is connected to the pinion gear which rotates
the differential through the gear mesh with the ring
gear bolted to the differential case. The engine power
is transmitted to the axle shafts through the pinion
BR/BEFRONT AXLE - 248FBI 3 - 45

mate and side gears. The side gears are splined to
the axle shafts.
During straight-ahead driving, the differential pin-
ion gears do not rotate on the pinion mate shaft. This
occurs because input torque applied to the gears is
divided and distributed equally between the two side
gears. As a result, the pinion gears revolve with the
pinion mate shaft but do not rotate around it (Fig. 2).When turning corners, the outside wheel must
travel a greater distance than the inside wheel to
complete a turn. The difference must be compensated
for to prevent the tires from scuffing and skidding
through turns. To accomplish this, the differential
allows the axle shafts to turn at unequal speeds (Fig.
3). In this instance, the input torque applied to the
pinion gears is not divided equally. The pinion gears
now rotate around the pinion mate shaft in opposite
directions. This allows the side gear and axle shaft
attached to the outside wheel to rotate at a faster
speed.
DIAGNOSIS AND TESTING - AXLE
GEAR NOISE
Axle gear noise can be caused by insufficient lubri-
cant, incorrect backlash, tooth contact, worn/damaged
gears or the carrier housing not having the proper
offset and squareness.
Gear noise usually happens at a specific speed
range. The noise can also occur during a specific type
of driving condition. These conditions are accelera-
tion, deceleration, coast, or constant load.
When road testing, first warm-up the axle fluid by
driving the vehicle at least 5 miles and then acceler-
ate the vehicle to the speed range where the noise is
the greatest. Shift out-of-gear and coast through the
peak-noise range. If the noise stops or changes
greatly:
²Check for insufficient lubricant.
²Incorrect ring gear backlash.
²Gear damage.
Differential side gears and pinions can be checked
by turning the vehicle. They usually do not cause
noise during straight-ahead driving when the gears
are unloaded. The side gears are loaded during vehi-
Fig. 1 248 FBI Differential Cover
1 - FILL PLUG
2 - MODEL NUMBER
3 - RATIO TAG
4 - DIFFERENTIAL COVER
Fig. 2 Differential Operation-Straight Ahead Driving
1 - IN STRAIGHT AHEAD DRIVING EACH WHEEL ROTATES AT
100% OF CASE SPEED
2 - PINION GEAR
3 - SIDE GEAR
4 - PINION GEARS ROTATE WITH CASE
Fig. 3 Differential Operation-On Turns
1 - PINION GEARS ROTATE ON PINION SHAFT
3 - 46 FRONT AXLE - 248FBIBR/BE
FRONT AXLE - 248FBI (Continued)

cle turns. A worn pinion mate shaft can also cause a
snapping or a knocking noise.
BEARING NOISE
The axle shaft, differential and pinion bearings can
all produce noise when worn or damaged. Bearing
noise can be either a whining, or a growling sound.
Pinion bearings have a constant-pitch noise. This
noise changes only with vehicle speed. Pinion bearing
noise will be higher pitched because it rotates at a
faster rate. Drive the vehicle and load the differen-
tial. If bearing noise occurs, the rear pinion bearing
is the source of the noise. If the bearing noise is
heard during a coast, the front pinion bearing is the
source.
Worn or damaged differential bearings usually pro-
duce a low pitch noise. Differential bearing noise is
similar to pinion bearing noise. The pitch of differen-
tial bearing noise is also constant and varies only
with vehicle speed.
Axle shaft bearings produce noise and vibration
when worn or damaged. The noise generally changes
when the bearings are loaded. Road test the vehicle.
Turn the vehicle sharply to the left and to the right.
This will load the bearings and change the noise
level. Where axle bearing damage is slight, the noise
is usually not noticeable at speeds above 30 mph.
LOW SPEED KNOCK
Low speed knock is generally caused by a worn
U-joint or by worn side-gear thrust washers. A worn
pinion shaft bore will also cause low speed knock.
VIBRATION
Vibration at the rear of the vehicle is usually
caused by:
²Damaged drive shaft.²Missing drive shaft balance weight(s).
²Worn or out of balance wheels.
²Loose wheel lug nuts.
²Worn U-joint(s).
²Loose/broken springs.
²Damaged axle shaft bearing(s).
²Loose pinion gear nut.
²Excessive pinion yoke run out.
²Bent axle shaft(s).
Check for loose or damaged front end components
or engine/transmission mounts. These components
can contribute to what appears to be a rear end
vibration. Do not overlook engine accessories, brack-
ets and drive belts.
All driveline components should be examined
before starting any repair.
(Refer to 22 - TIRES/WHEELS - DIAGNOSIS AND
TESTING)
DRIVELINE SNAP
A snap or clunk noise when the vehicle is shifted
into gear (or the clutch engaged) can be caused by:
²High engine idle speed.
²Transmission shift operation.
²Loose engine/transmission/transfer case mounts.
²Worn U-joints.
²Loose spring mounts.
²Loose pinion gear nut and yoke.
²Excessive ring gear backlash.
²Excessive side gear to case clearance.
The source of a snap or a clunk noise can be deter-
mined with the assistance of a helper. Raise the vehi-
cle on a hoist with the wheels free to rotate. Instruct
the helper to shift the transmission into gear. Listen
for the noise, a mechanics stethoscope is helpful in
isolating the source of a noise.
BR/BEFRONT AXLE - 248FBI 3 - 47
FRONT AXLE - 248FBI (Continued)

DIAGNOSTIC CHART
Condition Possible Causes Correction
Wheel Noise 1. Wheel loose. 1. Tighten loose nuts.
2. Faulty, brinelled wheel bearing. 2. Replace bearing.
Axle Shaft Noise 1. Misaligned axle tube. 1. Inspect axle tube alignment. Correct
as necessary.
2. Bent or sprung axle shaft. 2. Inspect and correct as necessary.
3. End-play in pinion bearings. 3. Refer to pinion pre-load information
and correct as necessary.
4. Excessive gear backlash between the
ring gear and pinion.4. Check adjustment of the ring gear
and pinion backlash. Correct as
necessary.
5. Improper adjustment of pinion gear
bearings.5. Adjust the pinion bearings pre-load.
6. Loose pinion yoke nut. 6. Tighten the pinion yoke nut.
7. Scuffed gear tooth contact surfaces. 7. Inspect and replace as necessary.
Axle Shaft Broke 1. Misaligned axle tube. 1. Replace the broken shaft after
correcting tube mis-alignment.
2 Vehicle overloaded. 2. Replace broken shaft and avoid
excessive weight on vehicle.
3. Erratic clutch operation. 3. Replace broken shaft and avoid or
correct erratic clutch operation.
4. Grabbing clutch. 4. Replace broken shaft and inspect and
repair clutch as necessary.
Differential Cracked 1. Improper adjustment of the
differential bearings.1. Replace case and inspect gears and
bearings for further damage. Set
differential bearing pre-load properly.
2. Excessive ring gear backlash. 2. Replace case and inspect gears and
bearings for further damage. Set ring
gear backlash properly.
3. Vehicle overloaded. 3. Replace case and inspect gears and
bearings for further damage. Avoid
excessive vehicle weight.
4. Erratic clutch operation. 4. Replace case and inspect gears and
bearings for further damage. Avoid
erratic use of clutch.
Differential Gears Scored 1. Insufficient lubrication. 1. Replace scored gears. Fill differential
with the correct fluid type and quantity.
2. Improper grade of lubricant. 2. Replace scored gears. Fill differential
with the correct fluid type and quantity.
3. Excessive spinning of one wheel/tire. 3. Replace scored gears. Inspect all
gears, pinion bores, and shaft for
damage. Service as necessary.
3 - 48 FRONT AXLE - 248FBIBR/BE
FRONT AXLE - 248FBI (Continued)