DODGE RAM 1999 Service Repair Manual
Page 451 of 1691
DRIV E A XLE - T R AC -L O K
1999 D odge P ic ku p R 1500
1998-99 DRIVE AXLES
CHRY - Trac-Lok
Dakota, Ram Pickup, Ram Van/Wagon
IDENTIFICATION
TRAC-LOK DIFFERENTIAL APPLICATION (REAR AXLE) \
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Model Ring Gear Axle
Size Model
Dakota .................... 8 1/4" ........................... ( 1)
Ram Pickup ............ 9 3/4" ....................... 248 RBI
10 3/4" ....................... 267 RBI
11" ....................... 286 RBI
Ram Van/Wagon ............. 9 3/4" ....................... 248 RBI
( 1) - Manufacturer does not designate axle model.
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NOTE: For rear axles with limited-slip differentials, see POWER-LOK
- RAM PICKUP article.
DESCRIPTION & OPERATION
A Rear Beam-Design Iron (RBI) axle is an iron casting axle
and differential housing with axle shaft tubes extending from either
side. Tubes are pressed in to form a one-piece full-floating axle
housing.
Trac-Lok differential assembly is optional equipment. The
Trac-Lok differential assembly is a limited-slip type differential. It
is similar in operation to a conventional type differential, except
for 2 clutch packs located at the side gears in the differential case.
See Fig. 1 . Clutch packs provide differential action when required for
turning corners, and transmit equal torque to both wheels when driving
straight ahead.
AXLE RATIO & IDENTIFICATION
Axle ratio can be identified by axle identification tag
attached to axle housing cover. See AXLE RATIO SPECIFICATIONS table.
AXLE RATIO SPECIFICATIONS
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Application Ratio
Dakota ..................................... 3.21:1, 3.55:1 & 3.92:1
Ram Pickup
248 RBI .......................................... 3.55:1 & 4.10:1
267 & 286 RBI .................................... 3.54:1 & 4.10:1
Ram Van/Wagon ...................................... 3.55:1 & 4.10:1
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WARNING: Whenever rotating wheels, DO NOT use engine to rotate wheels
unless both rear wheels are off the ground and vehicle is
securely supported.
Page 452 of 1691
LUBRICATION
CAPACITY
DRIVE AXLE CAPACITY ( 1) \
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Application ( 2) Pts. (L)
Dakota .................................................... 4.7(2.2)\
Ram Pickup
248 RBI ................................................ 6.3 (3.0)\
267 RBI .................................................. 7 (3.3)\
286 RBI
2WD ................................................... 6.8 (3.2)\
4WD .................................................. 10.1 (4.8)\
Ram Van/Wagon ............................................ 6.3 (3.0)\
( 1) - Approximate drive axle capacity listed. Lubricant level should
be within 1/2" below bottom of oil filler hole in axle housing
cover.
( 2) - Add container of Mopar Gear Oil Friction Modifier when
refilling.
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FLUID TYPE
Use SAE 80W-90 or SAE 90W hypoid gear lubricant with MIL-L-
2105-C and API GL-5 ratings. Also add a container of Mopar Gear Oil
Friction Modifier when refilling.
FLUID DRAIN & REFILL
1) With lubricant of rear axle assembly at operating
temperature, raise and support vehicle so rear wheels are free to
rotate. Clean around axle housing cover. Loosen axle housing cover
bolts. Drain lubricant from axle housing. Remove bolts and axle
housing cover.
2) Position differential so hole in differential case is
facing downward. Wipe out all accessible areas of axle housing. Ensure
sealing surfaces on axle housing and cover are clean. Apply a 1/4"
thick bead of silicone sealant on inside of bolt holes and along
sealing surfaces on axle housing cover.
3) Install axle housing cover, axle identification tag and
retaining bolts. Tighten bolts to 30-35 ft. lbs. (41-47 N.m). Remove
oil filler plug. Add a container of Mopar Gear Oil Friction Modifier.
Fill axle with gear lube. Install oil filler plug. Lower vehicle.
TROUBLE SHOOTING
DIFFERENTIAL NOISE
1) Ensure differential lubricant is at normal operating
temperature. Road test vehicle. Note if differential noise exists in
turns, but not during straight-ahead driving. Probable cause is
incorrect or insufficient rear axle lubricant or additive.
2) Drain and refill rear axle. See FLUID DRAIN & REFILL under
LUBRICATION. Road test vehicle making 10-12 slow figure-8 turns and
note if noise still exists. It may be necessary to disassemble rear
axle so differential can be repaired. See RBI FULL FLOATING AXLES
article for removal of differential case.
Page 453 of 1691
TESTING
NOTE: Trac-Lok differential can be tested without removing
differential case from axle housing.
1) Place blocks under both front wheels. Ensure engine is off
and transmission is in Neutral. Release parking brake. Raise one rear
wheel until it is completely clear of the floor. Remove wheel. Install
Adapter (6790) to wheel studs and tighten securely.
2) Using torque wrench on adapter, rotate axle and record
torque required. Repeat procedure for remaining rear wheel position.
If rotational torque for either rear wheel is less than 30 ft. lbs.
(40.1 N.m) or greater than 200 ft. lbs. (271 N.m), Trac-Lok unit mus\
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be replaced or repaired.
REMOVAL & INSTALLATION
Servicing procedure is same as that used for standard
differential. See RBI FULL FLOATING AXLES article for servicing
procedures.
OVERHAUL
DIFFERENTIAL CARRIER
Disassembly
1) Place appropriate side gear holding tool in soft-jaw vise.
Position differential carrier on holding tool. Remove ring gear, if
necessary. Ring gear removal is only necessary when ring gear is being
replaced.
2) Remove roll pin holding pinion mate shaft into housing.
Remove pinion gear mate shaft. A drift and hammer can be used if
necessary. See Fig. 1.
3) Install appropriate Step Plate on lower side gear. Install
appropriate threaded forcing screw into upper side gear. See Fig. 2.
4) Thread Forcing Screw into threaded adapter disc until
forcing screw is centered in threaded adapter disc. Perform STEP 1
shown in illustration. See Fig. 2.
5) Place small screwdriver in slot of threaded adapter disc
to prevent disc from rotating. Tighten forcing screw to relieve
tension from clutch pack.
6) Remove pinion gear thrust washers. Loosen forcing screw to
release pressure from clutch pack. Install appropriate turning bar in
hole on side of differential case. Perform STEP 2 shown in
illustration. See Fig. 2.
7) Using turning bar, rotate differential case until pinion
gears can be removed. Remove pinion gears. Remove turning bar, forcing
screw, step plate, and threaded adapter disc from differential case.
8) Remove upper side gear and clutch pack. See Fig. 1. Remove
differential case from axle shaft. Remove remaining side gear and
clutch pack from differential case.
CAUTION: Mark clutch pack location for reassembly reference. Note
position of clutch pack components before removing clutch
pack retainers. Clutch packs must be assembled in correct
order and installed in original location.
9) Remove clutch pack retainers from clutch pack. Keeping
clutch pack components in correct order, disassemble clutch pack.
Page 454 of 1691
Fig. 1: Exploded View Of Trac-Lok Differential
Courtesy of Chrysler Corp.
Page 455 of 1691
Fig. 2: Removing Differential Case Components
Courtesy of Chrysler Corp.
NOTE: If any clutch pack components are defective, both clutch
packs must be replaced.
Page 456 of 1691
Cleaning & Inspection
1) Clean components with solvent and dry with compressed air.
Inspect plates in clutch pack for scoring, wear or damage.
2) Inspect remaining components for damage or wear. Replace
components if necessary.
Reassembly
1) Lubricate clutch pack components with gear lube.
Reassemble clutch packs. Ensure components are installed in correct
sequence and in original location. See Fig. 1. Install clutch pack
retainers on clutch packs.
2) Install clutch packs on respective side gears. Install
differential case on axle shaft. Install clutch pack and lower side
gear in differential case.
3) Install step plate on lower side gear. Install upper side
gear and clutch pack in differential case. Install threaded adapter
disc into upper side gear. Install forcing screw.
4) Tighten forcing screw to compress clutch packs. Install
pinion gears on side gears. Using turning bar, rotate differential
case until hole in differential case is aligned with pinion gears.
Remove turning bar.
5) Lubricate pinion gear thrust washers with gear lube.
Install pinion gear thrust washers. It may be necessary to tighten
forcing screw until pinion gear thrust washers can be installed.
6) Remove forcing screw, step plate and threaded adapter
disc. Using soft-face hammer, tap pinion shaft into differential case.
Install snap rings on pinion shaft (if equipped).
7) Install NEW roll pin. Stake differential case in 2 areas
to retain roll pin. Remove differential case from axle shaft. Install
ring gear on differential case. Install NEW ring gear bolts. DO NOT
reuse bolts. Tighten ring gear bolts evenly in alternating pattern to
specification. See TORQUE SPECIFICATIONS table.
TORQUE SPECIFICATIONS
TORQUE SPECIFICATIONS \
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Applications Ft. Lbs. (N.m)\
Axle Housing Cover Bolt .............................. 30-35 (41-47)\
Ring Gear Bolt
Dakota ................................................... 70 (95)\
All Others ..................................... 120-140 (163-190)\
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Page 457 of 1691
DRIV E S H AFTS & " U " J O IN TS - R W D
1999 D odge P ic ku p R 1500
1998-99 Drive Axles
CHRY - Drive Shafts & "U" Joints - RWD Trucks
Dakota, Ram Pickup, Ram Van/Wagon
DESCRIPTION
Drive shafts are balanced, tubular shafts with "U" joints
attached at each end. Flanges or yokes are used to connect drive shaft
"U" joints to rear differential pinion flange or to transmission
output shaft. "U" joint bearing caps are bolted to shaft flanges, or
are pressed into shaft yokes. Drive shafts can be steel or aluminum.
Number of drive shafts used by vehicle depends on vehicle
length and 4WD capability. Long wheel base vehicles use 2 rear drive
shafts with a center bearing support assembly. See Fig. 1. 4WD
applications use a double cardan constant velocity joint on front axle
drive shaft for correct drive shaft-to-front axle alignment. See
Fig. 12 .
Locations of slip joints and splined shafts vary with model
application. Single tube type drive shaft has slip joint on outside of
"U" joint flange/yoke. This slip joint slides in and out on
transmission's splined main shaft.
Fig. 1: Identifying Common Drive Shaft Combinations
Courtesy of Chrysler Corp.
LUBRICATION
Page 458 of 1691
Apply multipurpose lubricant (NLGI grade 2 EP) to "U" joints
and slip joint fittings.
INSPECTION
Abnormal vibration and noise can come from many driveline
sources. Drive shaft vibration/noise increases with vehicle speed
(MPH). A vibration that occurs within a specific speed is not caused
by drive shaft imbalance. Before overhauling driveline, check for
other causes/sources of possible vibration/noise.
TIRES & WHEELS
Check tire inflation and wheel balance. Check for foreign
objects in tread, damaged tread, mismatched tread patterns or
incorrect tire sizes. Check for bent wheels.
CENTER BEARING
Tighten drive shaft center bearing mounting bolts. If bearing
insulator is deteriorated or oil-soaked, or drive shaft can be moved
up/down in support, replace center bearing support assembly.
ENGINE & TRANSMISSION MOUNTS
Tighten mounting bolts. If rubber mounts are deteriorated or
broken, replace as needed.
DRIVE SHAFT(S)
Check drive shaft(s) for missing weights, broken welds, or
for dents affecting balance. Check for undercoating, mud, snow/ice on
drive shaft(s). Clean shafts thoroughly and test drive.
"U" JOINTS
Check for foreign material lodged in joints and flange/yokes.
Check for loose "U" joint-to-flange mounting bolts. Check for worn "U"
joint needle bearings. Check for Reddish-Brown rust-dust around "U"
joint caps. Replace "U" joints if necessary.
ADJUSTMENTS
CHECKING DRIVE SHAFT PHASING
One-Piece Drive Shafts
1) Ensure "U" joint flanges on either end of drive shaft are
in same plane. See Fig. 2. Drive shafts with slip joints between yokes
often have arrows to aid in alignment. If yokes are not in same plane,
disassemble slip joint from drive shaft splines. Install slip joint
back onto drive shaft splines, aligning "U" joint yokes. Test drive.
2) Single tube type drive shaft has slip joint on outside of
"U" joint yoke (at transmission end). If one-piece tube type drive
shaft yokes are out of alignment, the drive shaft is torque-twisted.
Drive shaft must be replaced.
Page 459 of 1691
Fig. 2: Checking Phase Alignment Of One-Piece Drive Shaft
2-Piece Shafts
1) On most models with 2-piece drive shafts, proper yoke
phasing is accomplished by keys on drive shaft spline and keyway in
slip joint splines. Drive shafts of this type will fit together only
one way. Non-key drive shafts will fit together in any order on
spline.
2) Rotate transmission flange/yoke until flange/yoke ears
(trunnion axis) are in horizontal plane. Install front drive shaft-to-\
transmission flange/yoke keeping flange/yoke in horizontal plane. This
puts both flange/yoke ears of front drive shaft in vertical plane. See
Fig. 3 .
3) Connect center bearing support assembly to crossmember
bracket. Ensure front face of center bearing support assembly is
perpendicular (90
) to center line of drive shaft. If center bearing
support assembly is installed crooked or off center, drive shaft
vibration and/or noise will result. See Fig. 8.
4) Align and install rear drive shaft splines into slip yoke
splines while keeping rear drive shaft flange/yoke in horizontal
plane. Drive shaft rear "U" joint mounting caps will be in vertical
plane. Set differential pinion flange in vertical plane. Connect rear
drive shaft-to-pinion flange. If 2-piece shaft is correctly installed,
center line of flange/yokes trunnion axis for each individual shaft
will be parallel. See Fig. 3.
Fig. 3: Checking Phase Alignment Of 2-Piece Drive Shaft
Courtesy of Chrysler Corp.
CHECKING RUNOUT
Page 460 of 1691
1) On drive shafts greater than 30" in length, measure runout
3" from transmission flange/yoke, center bearing yoke and pinion
flange using dial indicator. Maximum runout for Ram Pickup is .030" (.
76 mm) at front and rear end of drive shaft and .035" (.89 mm) at
center of drive shaft. Maximum runout for all other models is .010" (.
25 mm) at front and rear end of drive shaft and .015" (.38 mm) at
center of drive shaft.
2) For drive shafts less than 30" in length, maximum runout
for Pickup is .030" (.76 mm). Maximum runout for all other models is .\
020" (.51 mm). Replace drive shaft if maximum runout is exceeded.
BALANCING DRIVE SHAFT
1) Perform following procedure only after inspecting all
other possible causes of vibration. See INSPECTION. Drive shaft
imbalance may often be cured by disconnecting shaft, rotating it 180
degrees and reconnecting shaft to flange. Test drive to check results.
NOTE: DO NOT run engine for prolonged periods without forced
airflow across radiator. Engine or transmission may
overheat.
2) To balance drive shaft(s), begin by raising rear wheels
off ground and turning drive shaft with engine. Balance testing may be
done by marking drive shaft in 4 positions, 90 degrees apart around
shaft. Place marks about 6" forward of rear flange/yoke weld. Number
marks 1-4.
3) Install large diameter screw-type hose clamp around drive
shaft so clamp's head is in No. 1 position. Spin drive shaft with
engine and note vibrations. If there is little or no change in
vibration intensity, move clamp head to No. 2 position, and repeat
test.
4) Continue procedure until vibration is at lowest level. If
no difference is noted with clamp head moved to all 4 positions,
vibrations may not be due to drive shaft imbalance.
5) If vibration decreases but is not completely eliminated,
place a second clamp at same position, and repeat test. Combined
weight of both clamps in one position may increase vibration. If so,
rotate clamps 1/2" apart, above and below lowest vibration level
position, and repeat test.
6) Continue to rotate clamps, as necessary, until vibration
is at lowest point. If vibration can be eliminated or reduced to
acceptable level, bend back slack end of clamp so screw cannot loosen.
If vibration level is still unacceptable, leave rear clamp(s) in
place, and repeat procedure at front end of drive shaft. Road test
vehicle. On 4WD models, perform procedure on each shaft.
CHECKING VERTICAL ANGLE
One-Piece Drive Shafts
1) Raise and support vehicle so rear wheels can be rotated.
Rotate drive shaft so a pinion flange bearing cap faces downward.
Attach Inclinometer (C-4224) magnet to bearing cap, and measure drive
shaft vertical angle. See Fig. 4. Remove inclinometer.
2) Rotate drive shaft 90 degrees until drive shaft rear yoke
bearing cap faces downward. Attach inclinometer magnet to bearing cap,
and measure drive shaft vertical angle. Difference between 2 measured
angles is drive shaft rear angle. See Fig. 5. Remove inclinometer.
3) Rotate drive shaft until a slip joint yoke bearing cap
faces downward. Attach inclinometer magnet to bearing cap, and note
angle. Remove inclinometer. Rotate drive shaft 90 degrees until drive
shaft front yoke bearing cap faces downward. Attach inclinometer
magnet to bearing cap, and note angle. Remove inclinometer.