2001 DODGE RAM differential

through the pinion 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. 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.
TRAC-LOKYDIFFERENTIAL
The Trac-lokyclutches are engaged by two concur-
rent forces. The first being the preload force exerted
through Belleville spring washers within the clutch
packs. The second is the separating forces generated
by the side gears as torque is applied through the
ring gear (Fig. 3).
The Trac-lokydesign provides the differential
action needed for turning corners and for driving
straight ahead during periods of unequal traction.
When one wheel looses traction, the clutch packs
transfer additional torque to the wheel having the
most traction. Trac-lokydifferentials resist wheel spin
Fig. 1 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. 2 Differential Operation - On Turns
1 - PINION GEARS ROTATE ON PINION SHAFT
Fig. 3 Trac-lokYLimited Slip Differential
1 - CASE
2 - RING GEAR
3 - DRIVE PINION
4 - PINION GEAR
5 - MATE SHAFT
6 - CLUTCH PACK
7 - SIDE GEAR
8 - CLUTCH PACK
3 - 170 REAR AXLE - 286RBIBR/BE
REAR AXLE - 286RBI (Continued)

on bumpy roads and provide more pulling power when
one wheel looses traction. Pulling power is provided
continuously until both wheels loose traction. If both
wheels slip due to unequal traction, Trac-lokyopera-
tion is normal. In extreme cases of differences of trac-
tion, the wheel with the least traction may spin.
DIAGNOSIS AND TESTING - AXLE
GEAR NOISE
Axle gear noise can be caused by insufficient lubri-
cant, incorrect backlash, incorrect pinion depth, 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-
cle turns. A worn pinion shaft can also cause a snap-
ping 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 changeswhen 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 a:
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 rearend vibra-
tion. Do not overlook engine accessories, brackets
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/BEREAR AXLE - 286RBI 3 - 171
REAR AXLE - 286RBI (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.
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.
3 - 172 REAR AXLE - 286RBIBR/BE
REAR AXLE - 286RBI (Continued)

Condition Possible Causes Correction
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.
Gear Teeth Broke 1. Overloading. 1. Replace gears. Examine other gears
and bearings for possible damage.
2. Erratic clutch operation. 2. Replace gears and examine the
remaining parts for damage. Avoid
erratic clutch operation.
3. Ice-spotted pavement. 3. Replace gears and examine
remaining parts for damage.
4. Improper adjustments. 4. Replace gears and examine
remaining parts for damage. Ensure ring
gear backlash is correct.
Axle Noise 1. Insufficient lubricant. 1. Fill differential with the correct fluid
type and quantity.
2. Improper ring gear and pinion
adjustment.2. Check ring gear and pinion contact
pattern. Adjust backlash or pinion depth.
3. Unmatched ring gear and pinion. 3. Replace gears with a matched ring
gear and pinion.
4. Worn teeth on ring gear and/or
pinion.4. Replace ring gear and pinion.
5. Loose pinion bearings. 5. Adjust pinion bearing pre-load.
6. Loose differential bearings. 6. Adjust differential bearing pre-load.
7. Mis-aligned or sprung ring gear. 7. Measure ring gear run-out. Replace
components as necessary.
8. Loose differential bearing cap bolts. 8. Inspect differential components and
replace as necessary. Ensure that the
bearing caps are torqued tot he proper
specification.
9. Housing not machined properly. 9. Replace housing.
REMOVAL
(1) Raise and support the vehicle.
(2) Position a suitable lifting device under the
axle.
(3) Secure axle to device.
(4) Remove the wheels and tires.
(5) Secure brake drums to the axle shaft.
(6) Remove the RWAL sensor from the differential
housing, if necessary. Refer to 5 Brakes for proce-
dures.
(7) Disconnect the brake hose at the axle junction
block. Do not disconnect the brake hydraulic lines at
the wheel cylinders. Refer to 5 Brakes for procedures.(8) Disconnect the parking brake cables and cable
brackets.
(9) Disconnect the vent hose from the axle shaft
tube.
(10) Mark the propeller shaft and companion
flange for installation alignment reference.
(11) Remove propeller shaft.
(12) Disconnect shock absorbers from axle.
(13) Remove the spring clamps and spring brack-
ets. Refer to 2 Suspension for procedures.
(14) Separate the axle from the vehicle.
BR/BEREAR AXLE - 286RBI 3 - 173
REAR AXLE - 286RBI (Continued)

INSTALLATION
(1) Raise the axle with lifting device and align to
the leaf spring centering bolts.
(2) Install the spring clamps and spring brackets.
Refer to 2 Suspension for procedures.
(3) Install shock absorbers and tighten nuts to 82
N´m (60 ft. lbs.).
(4) Install the RWAL sensor to the differential
housing, if necessary. Refer to 5 Brakes for proce-
dures.
(5) Connect the parking brake cables and cable
brackets.
(6) Install the brake drums. Refer to 5 Brakes for
procedures.
(7) Connect the brake hose to the axle junction
block. Refer to 5 Brakes for procedures.
(8) Install axle vent hose.
(9) Align propeller shaft and pinion companion
flange reference marks. Install the companion flange
bolts. Tighten to 108 N´m (80 ft. lbs.).
(10) Install the wheels and tires.
(11) Add gear lubricant, if necessary. Refer to
Specifications for lubricant requirements.
(12) Remove lifting device from axle and lower the
vehicle.
ADJUSTMENTS
Ring and pinion gears are supplied as matched
sets only. The identifying numbers for the ring and
pinion gear are etched into the face of each gear (Fig.
4). A plus (+) number, minus (±) number or zero (0) is
etched into the face of the pinion gear. This number
is the amount (in thousandths of an inch) the depth
varies from the standard depth setting of a pinion
etched with a (0). The standard setting from the cen-
ter line of the ring gear to the back face of the pinion
is 147.625 mm (5.812 in.). The standard depth pro-
vides the best teeth contact pattern. Refer to Back-
lash and Contact Pattern Analysis Paragraph in this
section for additional information.
Compensation for pinion depth variance is
achieved with select shims. The shims are placed
under the inner pinion bearing cone (Fig. 5).
If a new gear set is being installed, note the depth
variance etched into both the original and replace-
ment pinion gear. Add or subtract the thickness of
the original depth shims to compensate for the differ-
ence in the depth variances. Refer to the Depth Vari-
ance charts.
Note where Old and New Pinion Marking columns
intersect. Intersecting figure represents plus or
minus amount needed.
Note the etched number on the face of the drive
pinion gear (±1, ±2, 0, +1, +2, etc.). The numbers rep-
resent thousands of an inch deviation from the stan-dard. If the number is negative, add that value to the
required thickness of the depth shim(s). If the num-
ber is positive, subtract that value from the thickness
of the depth shim(s). If the number is 0 no change is
necessary. Refer to the Pinion Gear Depth Variance
Chart.
Fig. 4 Pinion Gear ID Numbers
1 - PRODUCTION NUMBERS
2 - PINION GEAR DEPTH VARIANCE
3 - GEAR MATCHING NUMBER
Fig. 5 Adjustment Shim Locations
1 - PINION BEARING PRELOAD SHIM
2 - DIFFERENTIAL BEARING SHIM
3 - PINION GEAR DEPTH SHIM
3 - 174 REAR AXLE - 286RBIBR/BE
REAR AXLE - 286RBI (Continued)

PINION GEAR DEPTH VARIANCE
Original Pinion
Gear Depth
VarianceReplacement Pinion Gear Depth Variance
þ4 þ3 þ2 þ1 0 +1 +2 +3 +4
+4+0.008 +0.007 +0.006 +0.005 +0.004 +0.003 +0.002 +0.001 0
+3+0.007 +0.006 +0.005 +0.004 +0.003 +0.002 +0.001 0 þ0.001
+2+0.006 +0.005 +0.004 +0.003 +0.002 +0.001 0 þ0.001 þ0.002
+1+0.005 +0.004 +0.003 +0.002 +0.001 0 þ0.001 þ0.002 þ0.003
0+0.004 +0.003 +0.002 +0.001 0 þ0.001 þ0.002 þ0.003 þ0.004
þ1+0.003 +0.002 +0.001 0 þ0.001 þ0.002 þ0.003 þ0.004 þ0.005
þ2+0.002 +0.001 0 þ0.001 þ0.002 þ0.003 þ0.004 þ0.005 þ0.006
þ3+0.001 0 þ0.001 þ0.002 þ0.003 þ0.004 þ0.005 þ0.006 þ0.007
þ40 þ0.001 þ0.002 þ0.003 þ0.004 þ0.005 þ0.006 þ0.007 þ0.008
PINION DEPTH MEASUREMENT AND ADJUSTMENT
Measurements are taken with pinion cups and pin-
ion bearings installed in housing. Take measure-
ments with a Pinion Gauge Set 6730 and Dial
Indicator C-3339 (Fig. 6).(1) Assemble Pinion Height Block 6739, Pinion
Block 6738 and rear pinion bearing onto Screw 6741
(Fig. 6).
(2) Insert assembled height gauge components,
rear bearing and screw into the housing through pin-
ion bearing cups (Fig. 7).
(3) Install front pinion bearing and Cone 6740
hand tight (Fig. 6).
(4) Place Arbor Disc 6732 on Arbor D-115-3 in posi-
tion in the housing side bearing cradles (Fig. 8).
Install differential bearing caps on Arbor Discs and
snug the bearing cap bolts. Then tighten cap bolts in
a criss-cross pattern to 108 N´m (80 ft. lbs.).
NOTE: Arbor Discs 6732 have different step diame-
ters to fit other axle sizes. Pick correct size step for
axle being serviced.
Fig. 6 Pinion Gear Depth Gauge
1 - DIAL INDICATOR
2 - ARBOR
3 - PINION HEIGHT BLOCK
4 - CONE
5 - SCREW
6 - PINION BLOCK
7 - SCOOTER BLOCK
8 - ARBOR DISC
Fig. 7 Pinion Height Block
1 - PINION BLOCK
2 - PINION HEIGHT BLOCK
BR/BEREAR AXLE - 286RBI 3 - 175
REAR AXLE - 286RBI (Continued)

(5) Assemble Dial Indicator C-3339 into Scooter
Block D-115-2 and secure set screw.
(6) Place Scooter Block/Dial Indicator in position
in the housing so dial probe and scooter block are
flush against the surface of the pinion height block.
Hold scooter block in place and zero the dial indica-
tor face to the pointer. Tighten dial indicator face
lock screw.
(7) With scooter block still in position against the
pinion height block, slowly slide the dial indicator
probe over the edge of the pinion height block.
Observe how many revolutions counterclockwise the
dial pointer travels (approximately 0.125 in.) to the
out-stop of the dial indicator.
(8) Slide the dial indicator probe across the gap
between the pinion height block and the arbor bar
with the scooter block against the pinion height block
(Fig. 9). When the dial probe contacts the arbor bar,
the dial pointer will turn clockwise. Bring dial
pointer back to zero against the arbor bar, do not
turn dial face. Continue moving the dial probe to the
crest of the arbor bar and record the highest reading.
If the dial indicator can not achieve the zero reading,
the rear bearing cup or the pinion depth gauge set is
not installed correctly.
(9) Select a shim equal to the dial indicator read-
ing plus the drive pinion gear depth variance number
etched in the face of the pinion gear (Fig. 4) using
the opposite sign on the variance number. For exam-
ple, if the depth variance is ±2, add +0.002 in. to the
dial indicator reading.
(10) Remove the pinion depth gauge components
from the axle housingDIFFERENTIAL BEARING PRELOAD AND GEAR
BACKLASH
Differential side bearing preload and gear backlash
is achieved by selective shims positioned behind the
differential side bearing cones. The proper shim
thickness can be determined using slip-fit dummy
bearings D-346 in place of the differential side bear-
ings and a dial indicator C-3339. Before proceeding
with the differential bearing preload and gear back-
lash measurements, measure the pinion gear depth
and prepare the pinion gear for installation. Estab-
lishing proper pinion gear depth is essential to estab-
lishing gear backlash and tooth contact patterns.
After the overall shim thickness to take up differen-
tial side play is measured, the pinion gear is
installed, and the gear backlash shim thickness is
measured. The overall shim thickness is the total of
the dial indicator reading and the preload specifica-
tion added together. The gear backlash measurement
determines the thickness of the shim used on the
ring gear side of the differential case. Subtract the
gear backlash shim thickness from the total overall
shim thickness and select that amount for the pinion
gear side of the differential (Fig. 10). Differential
shim measurements are performed with axle
spreader W-129-B removed.
SHIM SELECTION
NOTE: It is difficult to salvage the differential side
bearings during the removal procedure. Install
replacement bearings if necessary.
(1) Remove differential side bearings from differ-
ential case.
Fig. 8 Gauge Tools In Housing
1 - ARBOR DISC
2 - PINION BLOCK
3 - ARBOR
4 - PINION HEIGHT BLOCKFig. 9 Pinion Gear Depth Measurement
1 - ARBOR
2 - SCOOTER BLOCK
3 - DIAL INDICATOR
3 - 176 REAR AXLE - 286RBIBR/BE
REAR AXLE - 286RBI (Continued)

(2) Remove factory installed shims from differen-
tial case.
(3) Install ring gear on differential case and
tighten bolts to specification, if necessary.
(4) Install dummy side bearings D-346 on differen-
tial case.
(5) Install differential case in the housing.
(6) Install the marked bearing caps in their correct
positions. Install and snug the bolts (Fig. 11).(7) Using a dead-blow hammer, seat the differen-
tial dummy bearings to each side of the housing (Fig.
12) and (Fig. 13).
(8) Thread Pilot Stud C-3288-B into rear cover bolt
hole below ring gear (Fig. 14).
(9) Attach a dial indicator C-3339 to pilot stud.
Position the dial indicator plunger on a flat surface
between the ring gear bolt heads (Fig. 14).
(10) Push and hold differential case to pinion gear
side of the housing and zero dial indicator (Fig. 15).
(11) Push and hold differential case to ring gear
side of the housing and record dial indicator reading
(Fig. 16).
Fig. 10 Adjustment Shim Locations
1 - PINION BEARING PRELOAD SHIM
2 - DIFFERENTIAL BEARING SHIM
3 - PINION GEAR DEPTH SHIM
Fig. 11 Bearing Cap Bolts
1 - BEARING CAP
2 - DIFFERENTIAL HOUSING
3 - DIFFERENTIAL CASE
Fig. 12 Seat Pinion Gear Side Dummy Bearing
1 - DEAD-BLOW HAMMER
2 - DIFFERENTIAL HOUSING
3 - DIFFERENTIAL CASE
Fig. 13 Seat Ring Gear Side Dummy Bearing
1 - DIFFERENTIAL HOUSING
2 - DEAD-BLOW HAMMER
3 - DIFFERENTIAL CASE
BR/BEREAR AXLE - 286RBI 3 - 177
REAR AXLE - 286RBI (Continued)