2002 DODGE RAM Service Repair Manual

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Page 65 of 2255

DODGE RAM 2002 Service Repair Manual (3) Place a bearing cap over the trunnion and
align the cap with the yoke bore (Fig. 16). Keep the
needle bearings upright in the bearing assembly.
(4) Press the bearing cap into the yoke bore
enough

Page 66 of 2255

DODGE RAM 2002 Service Repair Manual (9) Grasp protruding bearing cap with vise jaws
and tap link yoke with a mallet and drift to remove
bearing cap (Fig. 19).
(10) Flip assembly and repeat Step 6, Step 7, Step
8 and Step 9 to remove the

Page 67 of 2255

DODGE RAM 2002 Service Repair Manual (4) Press bearing cap into the yoke bore enough to
clear snap ring groove (Fig. 23).
(5) Install a snap ring.
(6) Flip propeller shaft yoke and install other bear-
ing cap onto the opposite trunnion a

Page 68 of 2255

DODGE RAM 2002 Service Repair Manual (9) Place two bearing caps on opposite trunnions of
the remaining cross. Fit the open trunnions into the
link yoke bores and the bearing caps into the center-
ing kit (Fig. 27).
(10) Press the remaini

Page 69 of 2255

DODGE RAM 2002 Service Repair Manual FRONT AXLE - 248FBI
TABLE OF CONTENTS
page page
FRONT AXLE - 248FBI
DESCRIPTION.........................14
OPERATION...........................14
DIAGNOSIS AND TESTING - AXLE..........15
REMOVAL......

FRONT AXLE - 248FBI
TABLE OF CONTENTS
page page
FRONT AXLE - 248FBI
DESCRIPTION.........................14
OPERATION...........................14
DIAGNOSIS AND TESTING - AXLE..........15
REMOVAL.............................18
INSTALLATION.........................18
ADJUSTMENTS........................19
SPECIFICATIONS
FRONT AXLE - 248FBI.................27
SPECIAL TOOLS
FRONT AXLE........................27
AXLE SHAFTS
REMOVAL.............................29
INSTALLATION.........................29
AXLE SHAFTS - INTERMEDIATE
REMOVAL.............................30
INSTALLATION - INTERMEDIATE AXLE......30
AXLE SHAFT SEALS
REMOVAL.............................31
INSTALLATION.........................31
AXLE VACUUM MOTOR
DESCRIPTION.........................31
OPERATION...........................31DIAGNOSIS AND TESTING - VACUUM MOTOR . 32
REMOVAL.............................34
DISASSEMBLY.........................34
ASSEMBLY............................34
INSTALLATION.........................34
SINGLE CARDAN UNIVERSAL JOINTS
REMOVAL.............................34
INSTALLATION.........................35
PINION SEAL
REMOVAL.............................35
INSTALLATION.........................35
DIFFERENTIAL
REMOVAL.............................37
DISASSEMBLY.........................38
ASSEMBLY............................38
INSTALLATION.........................39
DIFFERENTIAL CASE BEARINGS
REMOVAL.............................40
INSTALLATION.........................41
PINION GEAR/RING GEAR
REMOVAL.............................41
INSTALLATION.........................43
FRONT AXLE - 248FBI
DESCRIPTION
The Front Beam-design Iron (FBI) axle consists of a
cast iron center casting differential housing with axle
shaft tubes extending from each side. The tubes are
pressed into the differential housing and welded. The
axles is equipped with semi-floating axle shafts, mean-
ing that loads are supported by the hub bearings.
The differential case is a one-piece design. Differ-
ential bearing preload and ring gear backlash is
adjusted by the use of shims located between the dif-
ferential bearing cones and case. Pinion bearing pre-load is set and maintained by the use of a collapsible
spacer. The stamped steel cover provides a means for
inspection and servicing the differential.
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
mate and side gears. The side gears are splined to
the axle shafts.
3 - 14 FRONT AXLE - 248FBIBR/BE

Page 70 of 2255

DODGE RAM 2002 Service Repair Manual 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

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. 1).
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.
2). 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 thepeak-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-
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.
Fig. 1 DIFFERENTIAL-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. 2 DIFFERENTIAL-ON TURNS
1 - PINION GEARS ROTATE ON PINION SHAFT
BR/BEFRONT AXLE - 248FBI 3 - 15
FRONT AXLE - 248FBI (Continued)

Page 71 of 2255

DODGE RAM 2002 Service Repair Manual 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

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.
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.
3 - 16 FRONT AXLE - 248FBIBR/BE
FRONT AXLE - 248FBI (Continued)

Page 72 of 2255

DODGE RAM 2002 Service Repair Manual Condition Possible Causes Correction
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

Condition Possible Causes Correction
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.
Loss Of Lubricant 1. Lubricant level too high. 1. Drain lubricant to the correct
level.
2. Worn axle shaft seals. 2. Replace seals.
3. Cracked differential housing. 3. Repair as necessary.
4. Worn pinion seal. 4. Replace seal.
5. Worn/scored yoke. 5. Replace yoke and seal.
6. Axle cover not properly sealed. 6. Remove, clean, and re-seal
cover.
Axle Overheating 1. Lubricant level low. 1. Fill differential to correct level.
2. Improper grade of lubricant. 2. Fill differential with the correct
fluid type and quantity.
3. Bearing pre-loads too high. 3. Re-adjust bearing pre-loads.
4. Insufficient ring gear backlash. 4. Re-adjust ring gear backlash.
BR/BEFRONT AXLE - 248FBI 3 - 17
FRONT AXLE - 248FBI (Continued)

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