Differential and Driveline — part 2 of 3 — 1996 Jeep Grand Cherokee ZJ Service Manual
← Contents 1 2 3
Pages 102–161 · 60 pages · 3 words repaired
DISASSEMBLY AND ASSEMBLY
STANDARD DIFFERENTIAL
DISASSEMBLE
(1) Remove pinion gear mate shaft. (2) Rotate the differential side gears and remove the pinion mate gears and thrust washers (Fig. 40).
Fig. 41 Trac–Lok Differential Components
(3) Remove the differential side gears and thrust washers.
DIFFERENTIAL ASSEMBLE
(1) Differential side gears and thrust washers (2) Pinion gears and thrust washers (3) Pinion gear mate shaft (align holes in shaft and case)
(4) Lubricate all differential components with hypoid gear lubricant.
(5) Install differential case in axle housing. Refer to Differential removal and installation procedure.
TRAC-LOK DIFFERENTIAL
The Trac–Lok (limited–slip) differential components are illustrated in (Fig. 41). Refer to this illustration during repair service.
DISASSEMBLY
Service to the Trac–Lok differential requires the use of Tool Set 6960. Refer to Model 35 Axle section in this Group for Differential Removal and Installation.
(1) Clamp Side Gear Holding Tool 6965 in a vise. (2) Position the differential case on the holding tool (Fig. 42). Place shop towels under the differential to avoid damage if removal of the ring gear is required (Fig. 42).
(3) If ring gear replacement is required, remove and discard the bolts holding the ring gear to the case. Tap the ring gear with a rawhide or plastic mallet and separate ring gear from case (Fig. 43).
(4) Remove the pinion gear mate shaft lock screw (Fig. 44).
(5) Remove the pinion gear mate shaft. If necessary, use a drift and hammer (Fig. 45).
(6) Install and lubricate Step Plate 6960–3 (Fig. 46).
(7) Assemble Threaded Adapter 6960–1 into top side gear. Thread forcing Screw 6960–4 into adapter until it becomes centered in adapter plate.
(8) Position a small screw driver in slot of Threaded Adapter 6960–1 (Fig. 47) to prevent adapter from turning.
(9) Tighten forcing screw tool 122 N·m (90 ft. lbs.) (maximum) to compress Belleville springs in clutch packs (Fig. 48).
(10) Using a 0.020 in. feeler gauge and mallet, remove thrust washers from behind the pinion gears (Fig. 49).
(11) Loosen the forcing screw tool until the clutch pack tension is relieved and the pinion gears can be slightly rattled between the case and side gears.
(12) Insert Turning Bar 6960–2 in case. Rotate case with tool until pinion gears can be removed (Fig. 50).
(13) Remove top side gear and clutch pack. Keep plates in correct order during removal (Fig. 51).
(14) Remove case from fixture. Remove remaining clutch pack.
(15) Remove clutch pack retaining clips. Mark each clutch pack for installation reference.
ASSEMBLY
The clutch discs are replaceable as complete sets only. If one clutch disc pack is damaged, both packs must be replaced.
Lubricate each component with gear lubricant before assembly.
(1) Assemble the clutch discs into packs secure disc packs with retaining clips (Fig. 52).
(2) Position assembled clutch disc packs on the side gear hubs.
(3) Position case on axle fixture. (4) Install clutch pack and side gear in lower bore (Fig. 53). Be sure clutch pack retaining clips remain in position and are seated in the case pockets.
(5) Install lubricated Step Plate 6960–3 on first clutch pack (Fig. 54).
Installation
(6) Install the upper side gear and clutch disc pack (Fig. 54).
(7) Hold assembly in position. Insert Threaded Adapter 6960–1 into top side gear, insert forcing Screw 6960–4.
(8) Tighten forcing screw tool to slightly compress clutch discs.
(9) Place pinion gears in position in side gears and verify that mate shaft hole line up.
(10) Rotate case with Turning Bar 6960–2 until mate shaft holes in pinion gears align with holes in case.
(11) Tighten forcing screw to 122 N·m (90 ft. lbs.) to compress the Belleville springs. Lubricate and install thrust washers behind pinion gears and align washers with a small screw driver. Insert mate shaft into each pinion gear to verify alignment.
(12) Remove forcing screw, threaded adapter and step plate. Install pinion gear mate shaft, align holes in shaft and case.
(13) Install the pinion mate shaft lock screw finger tight to hold shaft during installation.
If replacement gears and thrust washers were installed, it is not necessary to measure the gear backlash. Correct fit is due to close machining tolerances during manufacture.
(14) Lubricate all differential components with hypoid gear lubricant.
CLEANING AND INSPECTION
AXLE COMPONENTS
Wash differential components with cleaning solvent and dry with compressed air. Do not steam clean the differential components.
Wash bearings with solvent and towel dry, or dry with compressed air. DO NOT spin bearings with compressed air. Cup and bearing must be replaced as matched sets only.
Clean axle shaft tubes and oil channels in housing. Inspect for; • Smooth appearance with no broken/dented surfaces on the bearing rollers or the roller contact surfaces
• Bearing cups must not be distorted or cracked • Machined surfaces should be smooth and without any raised edges
• Raised metal on shoulders of cup bores should be removed with a hand stone
• Wear and damage to pinion gear mate shaft, pinion gears, side gears and thrust washers. Replace as a matched set only.
• Ring and pinion gear for worn and chipped teeth • Ring gear for damaged bolt threads. Replaced as a matched set only.
• Pinion yoke for cracks, worn splines, pitted areas, and a rough/corroded seal contact surface. Repair or replace as necessary.
• Preload shims for damage and distortion. Install new shims if necessary.
TRAC-LOK
(1) Clean all components in cleaning solvent. Dry components with compressed air.
(2) Inspect clutch pack plates for wear, scoring or damage. Replace both clutch packs if any one component in either pack is damaged.
(3) Inspect side and pinion gears. Replace any gear that is worn, cracked, chipped or damaged.
(4) Inspect differential case and pinion shaft. Replace if worn or damaged.
PRESOAK PLATES AND DISC
Plates and discs with fiber coating (no grooves or lines) must be presoaked in Friction Modifier before assembly. Soak plates and discs for a minimum of 20 minutes. Add remaining Friction Modifier to differential after assembly.
ADJUSTMENTS
PINION GEAR DEPTH
GENERAL INFORMATION
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. 55). 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 center line of the ring gear to the back face of the pinion is 96.8 mm (3.813 inches) for Model 44 axles. The standard depth provides the best teeth contact pattern. Refer to Backlash and Contact Pattern Analysis Paragraph in this section for additional information.
NOTE: The button end on the pinion gear head is no longer a machined–to–specifications surface. Do not use this surface for pinion depth setup or checking (Fig. 56).
Compensation for pinion depth variance is achieved with select shims. The shims are placed under the inner pinion bearing cone (Fig. 57).
If a new gear set is being installed, note the depth variance etched into both the original and replacement pinion gear. Add or subtract the thickness of the original depth shims to compensate for the difference in the depth variances. Refer to the Depth Variance charts.
Note where Old and New Pinion Marking columns intersect. Intersecting figure represents plus or minus amount needed.
For example, if old pinion is plus (+) 1 and the new pinion is minus (–) 3, intersecting figure is (+) 0.004 in. (0.10 mm). Add this amount to the original shim.
PINION GEAR DEPTH VARIANCE
Or if the old pinion is (–) 3 and the new pinion is (–) 2, intersecting figure is (–) 0.001 in. (0.025 mm). Subtract this amount from original shim. Refer to the Pinion Gear Depth Variance Chart.
PINION DEPTH MEASUREMENT AND ADJUSTMENT
Pinion gear depth measurement is necessary when;
• Axle housing or differential case is replaced • Pinion select shim pack is unknown • Ring and pinion gears are replaced Measurements are taken with pinion cups and pinion bearings installed in housing. Take measurements with Pinion Gauge Set 6955, Pinion Block 6734 and Dial Indicator C–3339 (Fig. 58).
(1) Assemble Pinion Gauge Set, Pinion Block and pinion bearings. Install assembly into differential pinion gear bore and hand tighten cone (Fig. 59).
(2) Place Arbor Disc 6928 on Arbor D–115–3 and position in the bearing cradles (Fig. 60). Install differential bearing caps on Arbor Discs and tighten caps snug only.
Arbor Discs have different steps to fit other axle sizes. Pick correct size step for axle being serviced.
(3) Firmly place Scooter Block D-115–2 and Dial Indicator on pinion height block tool and zero the dial indicator pointer.
(4) Slide the Scooter Block across the arbor while observing indicator (Fig. 61). Record the longest
travel distance, whether inward (–) or outward (+), indicated by the pointer.
The plunger travel distance indicated, plus or minus the variance etched in the gear is the required thickness for the depth shims.
(5) Measure the thickness of each depth shim with a micrometer and combine the shims necessary for total required shim pack thickness.Include oil slinger or baffle thickness with the total shim pack thickness.
(6) Remove the measurement tools from the differential housing.
DIFFERENTIAL BEARING PRELOAD AND GEAR LASH
DIFFERENTIAL SHIM PACK MEASUREMENT
NOTE: It is recommended whenever bearings are removed that they be replaced.
(1) Install dummy side bearings 6927 on differential.
(2) Install the differential case in the axle housing. (3) Install the outboard shim/spacer (selected thickness) on each side between bearing cup and housing (Fig. 62). Use 0.142 in. (3.6 mm) as a starting point, shim/spacers are available in various thicknesses.
(4) Install the marked bearing caps in their correct positions. Install and snug the bolts.
(5) Attach a dial indicator to the housing. Position the indicator plunger so that it contacts the ring gear mating surface (Fig. 63).
(6) Pry the differential case to one side and zero the dial indicator pointer.
(7) Pry the differential case to the opposite side and record indicator reading. Reading is additional shim thickness needed for zero end play. For example, if reading was 0.008 in. (0.20 mm), an additional 0.004–in. (0.10 mm) thick shim will be needed at each side zero end play.
(8) Install zero end–play shims on each side of case.
The differential bearings must be preloaded to compensate for heat and load during operation.
(9) Add an additional 0.004–in. (0.1 mm) to each outboard shim/spacer for bearing preload.
(10) Remove differential from axle housing. (11) Remove dummy bearings. (12) Install new side bearing cones and cups. (13) Install ring gear. (14) Install differential and verify gear lash and contact pattern.
(15) Proceed to Final Assembly paragraph in this section.
GEAR BACKLASH AND CONTACT PATTERN ANALYSIS
After installing new side bearings or ring and pinion set adjusting the bearing perload and gear mash backlash will be necessary.
(1) Rotate assembly several revolutions to seat bearings. Measure backlash at three equally spaced locations around the perimeter of the ring gear with a dial indicator (Fig. 64).
The ring gear backlash must be within 0.12 – 0.20 mm (0.005 – 0.008 in.). It cannot vary more than 0.05 mm (0.002 in.) between the points checked.
If backlash must be adjusted, spacers are available in various thicknesses. Adjust the backlash accordingly (Fig. 65). Do not increase the total shim pack thickness, excessive bearing preload and damage will occur.
The ring gear teeth contact patterns will show if the pinion gear depth shim(s) have the correct thickness. It will also show if the ring gear backlash has been adjusted correctly. The backlash must be maintained within the specified limits until the correct tooth contact patterns are obtained.
(2) Apply a thin coat of hydrated ferric oxide, or equivalent, to the drive and coast side of the ring gear teeth.
(3) Rotate the ring gear one complete revolution in both directions while a load is being applied. Insert a pry bar between the differential housing and the case flange. This will produce distinct contact patterns on both the drive side and coast side of the ring gear teeth.
(4) Note patterns in compound. Refer to (Fig. 66) for interpretation of contact patterns and adjust accordingly.
SPECIFICATIONS
MODEL 35 AXLE
Axle Type. . . . . . . . . . . . . . . .Semi–Floating Hypoid Lubricant . . . . . . . .SAE Thermally Stable 80W–90 Lubricant Trailer Tow . . . . . . .Synthetic 75W–140 Lube Capacity. . . . . . . . . . . . . . . .1.66 L (3.50 pts.) Axle Ratio . . . . . . . . . . . . . . . .3.07, 3.55, 3.73, 4.10 Differential . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Bearing Preload. . . . . . . . . . . . . . .0.1 mm (0.004 in.) Side Gear Clearance. . . . . . .0–0.15 mm (0–0.006 in.) Ring Gear. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Diameter . . . . . . . . . . . . . . . . . . . .19.2 cm (7.562 in.) Backlash . . . . . . . . . . . .0–0.15 mm (0.005–0.008 in.) Pinion Std. Depth . . . . . . . . . . .96.8 mm (3.813 in.) Pinion Bearing Preload . . . . . . . . . . . . . . . . . . . . . Original Bearing . . . . . . . . . .1–2N·m (10–20 in. lbs.) New Bearing . . . . . . . . . . . .1.5–4N·m (15–35 in. lbs.)
MODEL 35 AXLE
DESCRIPTION TORQUE Fill Hole Plug. . . . . . . . . . . . . . .34 N·m (25 ft. lbs.) Diff. Cover Bolt . . . . . . . . . . . . .41 N·m (30 ft. lbs.) Bearing Cap Bolt . . . . . . . . . . . .77 N·m (57 ft. lbs.) Pinion Nut . . . . . . . .292–427 N·m (215–315 ft. lbs.) Ring Gear Bolt . . . . . . .95–122 N·m (70–90 ft. lbs.) RWAL/ABS Sensor Bolt . . . . . .24 N·m (18. ft. lbs.)
SPECIAL TOOLS
FRONT AXLE—MODEL 35
Puller—C-293-PA
Adapter—C-293-18
Adapter—C-293-39
Puller—C-452
Wrench—C-3281
Dial Indicator—C-3339
Driver—C-3716-A
Handle—C-4171
Trac-lok Tool—C-4487
Arbor, Pinion—W-115-3
Installer—D-130
Installer—D-146
Remover—D-147
Remover—D-148
Installer—D163
Plug—SP-3289
Installer—W-162-D
Installer—6436
Installer—6437
Disc, Axle Arbor—6732
Gauge Block—6735
Tool Set, Pinion Depth—6774
Trac-lok Tool Set—6960
Holder—6965
Puller—7794-A
MODEL 44 AXLE
INDEX
GENERAL INFORMATION
GENERAL INFORMATION . . . . . . . . . . . . . . . . . 75 LUBRICANT SPECIFICATIONS . . . . . . . . . . . . . . 75 DESCRIPTION AND OPERATION
AXLES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75 TRAC-LOK OPERATION . . . . . . . . . . . . . . . . . . . 76 DIAGNOSIS AND TESTING
DRIVELINE SNAP . . . . . . . . . . . . . . . . . . . . . . . 78 GEAR AND BEARING NOISE . . . . . . . . . . . . . . . 77 GENERAL INFORMATION . . . . . . . . . . . . . . . . . 77 LIMITED SLIP DIFFERENTIAL . . . . . . . . . . . . . . 78 LOW SPEED KNOCK . . . . . . . . . . . . . . . . . . . . . 78 REAR AXLE ALIGNMENT . . . . . . . . . . . . . . . . . . 78 SERVICE DIAGNOSIS . . . . . . . . . . . . . . . . . . . . 79 TRAC-LOK NOISE DIAGNOSIS . . . . . . . . . . . . . 81 VIBRATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78 SERVICE PROCEDURES
LUBRICANT CHANGE . . . . . . . . . . . . . . . . . . . . 81 REMOVAL AND INSTALLATION
AXLE SHAFT SEAL AND BEARING . . . . . . . . . . 84 AXLE SHAFT . . . . . . . . . . . . . . . . . . . . . . . . . . . 84 DIFFERENTIAL SIDE BEARINGS . . . . . . . . . . . . 87
GENERAL INFORMATION
GENERAL INFORMATION
The Model 44 housing has an aluminum center casting (differential housing) with axle shaft tubes extending from either side. The tubes are pressed into the differential housing to form a one–piece axle housing.
The integral type housing, hypoid gear design has the center line of the pinion set below the center line of the ring gear.
The axle has a vent hose to relieve internal pressure caused by lubricant vaporization and internal expansion.
The axles are equipped with semi–floating axle shafts, meaning that loads are supported by the axle shaft and bearings. The axle shafts are retained by C–clips in the differential side gears.
The cover provides a means for servicing the differential without removing the axle.
The differential case is a one–piece design. The differential pinion mate shaft is retained with a threaded pin. Differential bearing preload and ring gear backlash is adjusted by the use of spacer shims positioned between the side bearing race and the housing. Pinion bearing preload is set and maintained by the use of a collapsible spacer.
page page
DIFFERENTIAL . . . . . . . . . . . . . . . . . . . . . . . . . 85 FINAL ASSEMBLY . . . . . . . . . . . . . . . . . . . . . . . 91 PINION GEAR . . . . . . . . . . . . . . . . . . . . . . . . . . 88 PINION SHAFT SEAL REPLACEMENT . . . . . . . . 82 REAR AXLE . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82 RING GEAR . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87 DISASSEMBLY AND ASSEMBLY
STANDARD DIFFERENTIAL . . . . . . . . . . . . . . . 92 TRAC-LOK DIFFERENTIAL . . . . . . . . . . . . . . . . 92 CLEANING AND INSPECTION
AXLE COMPONENTS . . . . . . . . . . . . . . . . . . . . . 96 TRAC-LOK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96 ADJUSTMENTS
DIFFERENTIAL BEARING PRELOAD AND
GEAR LASH . . . . . . . . . . . . . . . . . . . . . . . . . . 99 PINION GEAR DEPTH . . . . . . . . . . . . . . . . . . . . 97 SPECIFICATIONS
MODEL 44 AXLE . . . . . . . . . . . . . . . . . . . . . . . 100 TORQUE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102 SPECIAL TOOLS
MODEL 44 AXLE . . . . . . . . . . . . . . . . . . . . . . . 102
LUBRICANT SPECIFICATIONS
Multi–purpose, hypoid gear lubricant should be used. The lubricant should have MIL–L–2105C and API GL 5 quality specifications. Mopar Hypoid Gear Lubricant conforms to both of these specifications.
• Lubricant is a thermally stable SAE 80W–90 gear lubricant.
• Lubricant for axle with Trailer Tow is SAE 75W–140 SYNTHETIC gear lubricant. • Trac–Lok differentials add 4 oz. of friction modifier. • Lubricant capacity is 1.66 L (3.50 pts.).
CAUTION: If axle is submerged in water, lubricant must be replaced immediately to avoid possible premature axle failure.
DESCRIPTION AND OPERATION
AXLES
ZJ vehicles are equipped with a Model 44 rear axle. The Model 44 axle housing has a cast aluminum center section. Two steel axle shaft tubes are pressed into the center section.
It is not necessary to remove the axle from the vehicle for service. A removable differential cover is provided for routine vehicle service. If the differential housing is damaged, the complete axle assembly can be removed.
For complete drive axle assembly removal and installation refer to Drive Axle Assembly Replacement in this Group.
IDENTIFICATION
Model 44 axle has the assembly part number and gear ratio listed on a tag. The tag is attached to the right side of the housing cover. Build date identification codes on axles are stamped on the axle shaft tube cover side. The Model 44 axle has a flat housing cover gasket flange at the outer edge.
STANDARD DIFFERENTIAL OPERATION
The differential gear system divides the torque between the axle shafts. It allows the axle shafts to rotate at different speeds when turning corners.
Each differential side gear is splined to an axle shaft. The pinion gears are mounted on a pinion mate shaft and are free to rotate on the shaft. The pinion gear is fitted in a bore in the differential case and is positioned at a right angle to the axle shafts.
In operation, power flow occurs as follows: • The pinion gear rotates the ring gear • The ring gear (bolted to the differential case) rotates the case
• The differential pinion gears (mounted on the pinion mate shaft in the case) rotate the side gears
• The side gears (splined to the axle shafts) rotate the shafts
During straight- ahead driving, the differential pinion 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 in order 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-LOK OPERATION
In a conventional differential, the torque applied to the ring gear is transmitted to the axle shafts through the differential gears. During normal operation, the torque transmitted to each wheel is equal at all times. However, if one wheel spins, the opposite wheel will generate only as much torque as the spinning wheel.
In the Trac-lok differential, part of the ring gear torque is transmitted through clutch packs. The clutch packs contain multiple disc. The clutch will have radial grooves on the plates, and concentric grooves on the discs or bonded fiber material that is smooth appearance.
In operation, the Trac-lok clutches are engaged by two concurrent forces. The first being preload force exerted through Belleville spring washers contained in the clutch packs. The second from separating forces generated by the side gears as torque is applied through the ring gear (Fig. 3).
The Trac-lok design provides differential action needed for turning corners and for driving straight ahead. However, when one wheel looses traction, the clutch packs transfer additional torque to the wheel having the most traction. Trac-lok differentials resist wheel spin 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-lok operation is normal. In extreme cases of differences of traction, the wheel with the least traction may spin.
DIAGNOSIS AND TESTING
GENERAL INFORMATION
The Model 44 housing has an aluminum center casting (differential housing) with axle shaft tubes extending from either side. The tubes are pressed into the differential housing to form a one–piece axle housing.
The integral type housing, hypoid gear design has the center line of the pinion set below the center line of the ring gear.
The axle has a vent hose to relieve internal pressure caused by lubricant vaporization and internal expansion.
The axles are equipped with semi–floating axle shafts, meaning that loads are supported by the axle shaft and bearings. The axle shafts are retained by C–clips in the differential side gears.
The cover provides a means for servicing the differential without removing the axle.
The differential case is a one–piece design. The differential pinion mate shaft is retained with a threaded pin. Differential bearing preload and ring gear backlash is adjusted by the use of spacer shims positioned between the side bearing race and the housing. Pinion bearing preload is set and maintained by the use of a collapsible spacer.
GEAR AND BEARING NOISE
GEAR NOISE
Axle gear noise can be caused by insufficient lubricant. Incorrect backlash, tooth contact, or worn/damaged gears can cause noise.
Gear noise usually happens at a specific speed range. The range is 30 to 40 mph, or above 50 mph. The noise can also occur during a specific type of driving condition. These conditions are acceleration, deceleration, coast, or constant load.
When road testing, accelerate 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, check for insufficient lubricant. Incorrect ring gear backlash, or gear damage can cause noise changes.
Differential side and pinion gears can be checked by turning the vehicle. They usually do not cause noise in straight–ahead driving. The side gears are loaded during vehicle turns. If noise does occur during vehicle turns, the side or pinion gears could be worn or damaged. A worn pinion gear mate shaft can also cause a snapping or a knocking noise.
BEARING NOISE
The axle shaft, differential and pinion gear bearings can all produce noise when worn or damaged. Bearing noise can be either a whining, or a growling sound.
Pinion gear bearings have a constant–pitch noise. This noise changes only with vehicle speed. Pinion bearing noise will be higher because it rotates at a faster rate. Drive the vehicle and load the differential. If bearing noise occurs the pinion rear bearing is the source of the noise. If the bearing noise is heard during a coast, front bearing is the source.
Worn, damaged differential bearings usually produce a low pitch noise. Differential bearing noise is similar to pinion bearing. The pitch of differential 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 gear shaft bore will also cause low speed knock.
VIBRATION
Vibration at the rear of the vehicle is usually caused by a:
• Damaged drive shaft • Missing drive shaft balance weight • Worn, out–of–balance wheels • Loose wheel lug nuts • Worn U–joint • Loose spring U–bolts • Loose/broken springs • Damaged axle shaft bearings • Loose pinion gear nut • Excessive pinion yoke run out • Bent axle shaft 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, brackets and drive belts.
All driveline components should be examined before starting any repair.
Refer to Group 22, Wheels and Tires for additional information.
DRIVELINE SNAP
A snap or clunk noise when the vehicle is shifted into gear (or the clutch engaged), can be caused by:
• High engine idle speed • Loose engine/transmission/transfer case mounts • Worn U–joints • Loose spring mounts • Loose pinion gear nut and yoke • Excessive ring gear backlash • Excessive side gear/case clearance The source of a snap or a clunk noise can be determined with the assistance of a helper. Raise the vehicle 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.
REAR AXLE ALIGNMENT
MEASUREMENT
The following procedure can be used to determine if abnormal rear tire tread wear is the result of a bent or deformed rear axle shaft.
(1) Raise both rear wheels off the surface with a frame contact hoist.
(2) Attach a one–inch long piece of masking tape at the center of each tire tread for use as reference marks.
(3) Rotate the rear wheels until both reference marks face the front of the vehicle. Measure the distance between the outside edges of the two pieces of tape. Record this measurement as the front of tire (FTR) measurement.
(4) Rotate the rear wheels until both reference marks face the rear of the vehicle. Measure the distance between the outside edges of the two pieces of tape. Record this measurement as the rear of tire (RTR) measurement.
(5) Subtract the (RTR) measurement from the (FTR) measurement to obtain the amount of wheel toe. The acceptable rear wheel toe–in position is 1/16 in. (1.6 mm) to 3/16 inch (4.8 mm) toe–out.
(6) Rotate the rear wheels until the reference marks are facing downward. Measure the distance between the outside edges of the two pieces of tape. Record this measurement as the bottom of tire (BTR) measurement.
(7) Average the (FTR) and the (RTR) distance measurements. Subtract the (BTR) measurement from this average distance to obtain the camber. The acceptable amount of camber is 1/16 inch to 3/32 inch (1.6 to 2.4 mm).
(FTR + RTR) DIVIDED BY 2 (TWO) MINUS BTR EQUALS CAMBER
If the (BTR) distance measurement is less than the average FTR and RTR distance measurement, the camber will be positive ( + ). If the (BTR) distance measurement is greater than the average FTR and RTR distance, the camber will be negative ( – ).
If the toe position or camber is not acceptable, a bent or deformed rear axle shaft is most likely the cause.
LIMITED SLIP DIFFERENTIAL
Under normal traction conditions, engine torque is divided evenly. With low–traction surfaces, engine torque is transferred to the wheel with the most tire traction. When diagnosing a limited–slip differential the wheel with the least traction can continue spinning.
The most common problem is a chatter noise when turning corners. Check for incorrect or contaminated lubricant. Replace the gear lubricant if necessary.
• With Trac–Loky differentials add a container of Mopar Trac–Lok Lubricant.
This will correct the condition in most instances. If the chatter persists, clutch damage could have occurred.
After changing the lubricant, drive the vehicle and make 10 to 12 slow, figure–eight turns. This maneuver will pump lubricant through the clutches.
SERVICE DIAGNOSIS SERVICE DIAGNOSIS
WHEEL NOISE 1. Wheel loose. 1. Tighten loose nuts.
2. Faulty, brinelled wheel bearing. 2. Faulty or brinelled bearings must be replaced.
AXLE SHAFT NOISE 1. Misaligned axle shaft tube. 1. Inspect axle shaft tube alignment. Correct as necessary.
2. Bent or sprung axle shaft. 2. Replace bent or sprung axle shaft.
3. End play in drive pinion 3. Refer to Drive Pinion Bearing Pre-Load Adjustment.
bearings.
A. Excessive gear backlash 4. Check adjustment of ring gear backlash and pinion gear.
; between ring gear and pinion Correct as necessary.
gear.
5. Improper adjustment of drive 5. Adjust drive pinion shaft bearings.
pinion gear shaft bearings.
6. Loose drive pinion gearshaft 6. Tighten drive pinion gearshaft yoke nut with specified torque.
yoke nut.
7. Improper wheel bearing 7. Readjust as necessary.
adjustment.
8. Scuffed gear tooth contact 8. If necessary, replace scuffed gears.
surfaces.
AXLE SHAFT BROKE 1. Misaligned axle shaft tube. 1. Replace broken axle shaft after correcting axle shaft tube
alignment.
2. Vehicle overloaded. 2. Replace broken axle shaft. Avoid excessive weight on vehicle.
3. Erratic clutch operation. 3. Replace broken axle shaft after inspecting for other possible
causes. Avoid erratic use of clutch.
4. Grabbing clutch. 4. Replace broken axle shaft. Inspect clutch and make necessary
repairs or adjustments.
| DIFFERENTIAL CASE 1. Improper adjustment of 1. Replace cracked case; examine gears and bearings for possible
CRACKED differential bearings. damage. At reassembly, adjust differential bearings properly.
2. Excessive ring gear backlash. 2. Replace cracked case; examine gears and bearings for possible
damage. At reassembly, adjust ring gear backlash properly.
3. Vehicle overloaded. 3. Replace cracked case; examine gears and bearings for possible
damage. Avoid excessive weight on vehicle.
A. Erratic clutch operation. 4, Replace cracked case. After inspecting for other possible
causes, examine gears and bearings for possible damage.
Avoid erratic use of clutch.
DIFFERENTIAL GEARS 1. Insufficient lubrication. 1. Replace scored gears. Scoring marks on the drive face of gear
SCORED teeth or in the bore are caused by instantaneous fusing of the
mating surfaces. Scored gears should be replaced. Fill rear
differential housing to required capacity with proper lubricant.
Refer to Specifications.
2. Improper grade of lubricant. 2. Replace scored gears. Inspect all gears and bearings for
possible damage. Clean and refill differential housing to
required capacity with proper lubricant.
3. Excessive spinning of one 3. Replace scored gears. Inspect all gears, pinion bores and shaft
wheell/tire. for damage. Service as necessary.
LOSS OF LUBRICANT 1. Lubricant level too high. 1. Drain excess lubricant by removing fill plug and allow lubricant
to level at lower edge of fill plug hole.
SERVICE DIAGNOSIS (CONT’D)
LOSS OF LUBRICANT 2. Worn axle shaft seals. 2. Replace worn seals.
3. Cracked differential housing. 3. Repair or replace housing as necessary.
4. Worn drive pinion gear shaft 4. Replace worn drive pinion gear shaft seal.
seal.
5. Scored and worn yoke. 5. Replace worn or scored yoke and seal.
6. Axle cover not properly sealed. 6. Remove cover and clean flange and reseal.
AXLE OVERHEATING 1. Lubricant level too low. 1. Refill differential housing.
2. Incorrect grade of lubricant. 2. Drain, flush and refill with correct amount of the correct
lubricant.
3. Bearings adjusted too tight. 3. Readjust bearings.
4. Excessive gear wear. 4. Inspect gears for excessive wear or scoring. Replace as
necessary.
5. Insufficient ring gear backlash. 5. Readjust ring gear backlash and inspect gears for possible
scoring.
GEAR TEETH BROKE 1. Overloading. 1. Replace gears. Examine other gears and bearings for possible
(RING GEAR AND PINION) damage.
2. Erratic clutch operation. 2. Replace gears and examine the remaining parts for possible
damage. Avoid erratic clutch operation.
3. Ice-spotted pavements. 3. Replace gears. Examine the remaining parts for possible
damage. Replace parts as required.
4. Improper adjustments. 4. Replace gears. Examine other parts for possible damage.
Ensure ring gear backlash is correct.
AXLE NOISE 1. Insufficient lubricant. 1. Refill axle with correct amount of the proper lubricant.
Also inspect for leaks and correct as necessary.
2. Improper ring gear and drive 2. Check ring gear and pinion gear teeth contact pattern.
pinion gear adjustment.
3. Unmatched ring gear and drive 3. Remove unmatched ring gear and drive pinion gear.
pinion gear. Replace with matched gear and drive pinion gear set.
4. Worn teeth on ring gear or 4. Check teeth on ring gear and drive pinion gear for correct
drive pinion gear. contact. If necessary, replace with new matched set.
5. Loose drive pinion gear shaft 5. Adjust drive pinion gearshaft bearing preload torque.
bearings.
6. Loose differential bearings. 6. Adjust differential bearing preload torque.
7. Misaligned or sprung ring gear. 7. Measure ring gear runout.
8. Loose differential bearing cap 8. Tighten with specified torque
bolts
J9503-4
TRAC-LOK NOISE DIAGNOSIS
If a noise occurs when turning corners, the most probable cause is incorrect or contaminated lubricant. Before removing the Trac-lok unit for repair, drain, flush and refill the axle with the specified lubricant. Refer to Lubricant change in this Group.
A container of Trac-lok Lubricant (friction modifier) should be added after repair service or a lubricant change.
Vehicles with a limited slip differential should be road tested by making 10 to 12 slow figure eight turns. This maneuver will pump the lubricant through the clutch discs to eliminate a possible chatter or pop noise complaint.
Refer to Group 0, Lubrication and Maintenance for additional information.
DIFFERENTIAL TEST
WARNING: WHEN SERVICING VEHICLES WITH A LIMITED SLIP DIFFERENTIAL DO NOT USE THE ENGINE TO TURN THE AXLE AND WHEELS. BOTH REAR WHEELS MUST BE RAISED AND THE VEHI- CLE SUPPORTED. A LIMITED SLIP AXLE CAN EXERT ENOUGH FORCE (IF ONE WHEEL IS IN CONTACT WITH THE SURFACE) TO CAUSE THE VEHICLE TO MOVE.
The differential can be tested without removing the differential case by measuring rotating torque. Make sure brakes are not dragging during this measurement.
(1) Engine off, transmission in neutral, and parking brake off.
(2) Place blocks in front and rear of both front wheels.
(3) Raise one rear wheel until it is completely off the ground.
(4) Remove wheel and bolt Special Tool 6790 to studs.
(5) Use torque wrench on special tool to rotate wheel and read rotating torque (Fig. 4).
(6) If rotating torque is less than 22 N·m (30 ft. lbs.) or more than 271 N·m (200 ft. lbs.) on either wheel the unit should be service.
SERVICE PROCEDURES
LUBRICANT CHANGE
The gear lubricant will drain quicker if the vehicle has been recently driven.
(1) Raise and support the vehicle. (2) Remove the lubricant fill hole plug from the differential housing cover.
(3) Remove the 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 the sealant from the housing and cover surfaces.
(6) Apply a bead of Mopar Silicone Rubber Sealant to the housing cover (Fig. 5). Allow the sealant to cure for a few minutes.
Install the housing cover within 5 minutes after applying the sealant.
(7) Install the cover and any identification tag. Tighten the cover bolts to 41 N·m (30 ft. lbs.) torque.
(8) Refill differential with Mopar Hypoid Gear Lubricant to bottom of the fill plug hole.
CAUTION: Overfilling the differential can result in lubricant foaming and overheating.
Trac–Lok Differentials; A container of Trac–Lok lubricant (friction modifier) should be added after repair service or a lubricant change.
(9) Install the fill hole plug and lower the vehicle. Limited slip differential vehicles should be road tested by making 10 to 12 slow figure–eight turns. This maneuver will pump the lubricant through the clutch discs to eliminate a possible chatter noise complaint.
REMOVAL AND INSTALLATION
REAR AXLE
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) Remove the brake components from the axle, refer to Group 5, Brakes.
(6) Disconnect the vent hose from the axle shaft tube.
(7) Mark the propeller shaft and yokes for installation alignment reference.
(8) Remove propeller shaft. (9) Disconnect stabilizer bar links. (10) Disconnect shock absorbers from axle. (11) Disconnect track bar. (12) Disconnect upper and lower suspension arms from the axle brackets.
(13) Separate the axle from the vehicle.
INSTALLATION
NOTE: The weight of the vehicle must be supported by the springs before suspension arms and track bar fasteners can be tightened. If the springs are not at their normal ride position, vehicle ride height and handling could be affected.
(1) Raise the axle with a floor jack and align coil springs.
(2) Position the upper and lower suspension arms on the axle brackets. Install nuts and bolts, do not tighten bolts at this time.
(3) Install track bar and attachment bolts, do not tighten bolts at this time.
(4) Install shock absorber and tighten nuts to 60 N·m (44 ft. lbs.) torque
(5) Install stabilizer bar link and tighten nuts to 36 N·m (27 ft. lbs.) torque
(6) Install brake components refer to Group 5 Brakes.
(7) Install axle vent hose (8) Align propeller shaft and pinion yoke reference marks. Install U-joint straps and bolts tighten to 19 N·m (14 ft. lbs.) torque
(9) Install the wheels and tires. (10) Check and add gear lubricant if needed. (11) Remove support and lower the vehicle. (12) Tighten lower suspension arms bolts to 177 N·m (130 ft. lbs.) torque.
(13) Tighten upper suspension arms bolts to 75 N·m (55 ft. lbs.) torque.
(14) Tighten track bar bolts to 100 N·m (74 ft. lbs.) torque.
PINION SHAFT SEAL REPLACEMENT
REMOVAL
(1) Raise and support the vehicle. (2) Remove wheel and tire assemblies. (3) Mark the drive shaft yoke and pinion yoke for installation alignment reference.
(4) Remove the drive shaft from the yoke. (5) Rotate the pinion gear three or four times. Make sure brakes are not dragging during this procedure.
(6) Measure the amount of torque (in Newton–meters or inch–pounds) necessary to rotate the pinion gear with a torque wrench. Note the torque for installation reference. It must be known to properly adjust the pinion gear bearing preload torque after seal installation.
(7) Remove the pinion yoke nut and washer. Use Remover C–452 and Wrench C–3281 to remove the pinion yoke (Fig. 6).
(8) Mark the positions of the yoke and pinion gear for installation alignment reference.
(9) Use Remover 7794A and slide hammer to remove the pinion gear seal (Fig. 7).
INSTALLATION
(1) Apply a light coating of gear lubricant on the lip of pinion seal. Install seal with Installer D–163 and Handle C–4171 (Fig. 8).
(2) Align the installation reference marks and install yoke on the pinion gear with Installer W–162D.
(3) Install a new nut on the pinion gear. Tighten the nut only enough to remove the shaft end play.
CAUTION: Exercise care during the bearing preload torque adjustment. Do not over–tighten, or loosen and then re–tighten the nut. Do not exceed the bearing preload torque. The collapsible preload spacer on the shaft will have to be replaced. The bearing preload torque will be re–adjusted afterward.
(4) Install a socket and inch–pound torque wrench on the pinion nut.
(5) Rotate the shaft with the torque wrench and note the torque (Fig. 9).
The required preload torque is equal to the amount recorded during removal plus an additional 0.56 N·m (5 in. lbs.).
(6) Use Flange Wrench 6719 to retain the yoke and shaft (Fig. 10). Tighten the shaft nut in very small increments.
(7) Continue tightening the shaft nut in small increments until the correct bearing rotation preload torque is attained.
(8) Align the installation reference marks and attach the drive shaft to the yoke.
(9) Add API grade GL 5 hypoid gear lubricant to the differential housing, if necessary.
(10) Install wheel and tire assemblies. (11) Lower the vehicle.
AXLE SHAFT
REMOVAL
(1) Raise and support the vehicle. (2) Remove the wheel and tire. (3) Remove the brake drum. (4) Clean all the foreign material from housing cover area.
(5) Loosen the housing cover bolts. Drain the lubricant from the housing and the axle shaft tubes. Remove the housing cover.
(6) Rotate the differential case so that the pinion mate gear shaft lock screw is accessible. Remove the lock screw and the pinion mate gear shaft from the case (Fig. 11).
(7) Force the axle shaft in toward the center of the vehicle. Remove the axle shaft C–clip lock from the axle shaft (Fig. 12).
(8) Remove the axle shaft. Use care to prevent damage to the axle shaft bearing and seal, which will remain in the axle shaft tube.
(9) Inspect axle shaft seal for leakage or damage. (10) Inspect the roller bearing contact surface on the axle shaft for signs of brinelling, galling and pitting.
(11) If any of these conditions exist, the axle shaft and bearing or seal must be replaced.
INSTALLATION
(1) Lubricate the bearing bore and seal lip with gear lubricant. Insert the axle shaft through the seal, bearing, and engage it with the side gear splines. Use care to prevent the shaft splines from damaging the axle shaft seal lip.
(2) Insert the C–clip lock in the end of the axle shaft. Push the axle shaft outward to seat the C–clip lock in the side gear.
(3) Insert the mate shaft into the case and through the thrust washers and pinion gears. Align the hole in shaft with the hole in the differential case and install the lock screw with Loctitet on the threads. Tighten the screw to 19 N·m (14 ft. lbs.) torque.
(4) Install the cover and add fluid. Refer to the Drain and Refill in this section.
AXLE SHAFT SEAL AND BEARING
REMOVAL
(1) Remove the axle shaft. Refer to the Removal procedures in this Group.
(2) Remove the axle shaft seal from the end of the axle shaft tube with a small pry bar.
(3) Remove the bearing if it appears damaged. The seal and bearing can be removed at the same time with the bearing removal tool.
(4) Remove the axle shaft bearing from the tube (Fig. 13) with Bearing Removal Tool Set 6310.
(5) Inspect the axle shaft tube bore for roughness and burrs. Remove as necessary.
CAUTION: Inspect the housing bore for burrs. Remove them if they exist.
INSTALLATION
Do not install the original axle shaft seal. Always install a new seal.
(1) Wipe the bore in the axle shaft tube clean.
(2) Install axle shaft bearing with Installer 6436 and Handle C–4171. Ensure part number on the bearing must go against the Installer.
(3) Install the new axle shaft seal (Fig. 14) with Installer 6437 and Handle C–4171.
(4) Install the Axle Shaft. Refer to the installation procedure.
DIFFERENTIAL
REMOVAL
To service the differential the axle shafts must be removed. Refer to the removal procedures in this Group.
(1) Note the installation reference letters stamped on the bearing caps and housing machined sealing surface (Fig. 15).
(2) Remove the differential bearing caps. (3) Position Spreader W–129–B with the tool dowel pins seated in the locating holes (Fig. 16). Install the hold down clamps and tighten the tool turnbuckle finger–tight.
(4) Install a pilot stud at the left side of the differential housing. Attach Dial Indicator to housing pilot stud. Load the indicator plunger against the opposite side of the housing (Fig. 16) and zero the indicator.
CAUTION: Do not spread over 0.38 mm (0.015 in). If the housing is over–separated, it could be distorted or damaged.
(5) Separate the housing enough to remove the case from the housing. Measure the distance with the dial indicator (Fig. 16).
(6) Remove the dial indicator. (7) Pry the differential case loose from the housing. To prevent damage, pivot on housing with the end of the pry bar against spreader (Fig. 17).
(8) Remove the case from housing. Mark or tag bearing cups and outboard shim/spacer (selected thickness) indicating which side they were removed.
DIFFERENTIAL INSTALLATION
(1) Position Spreader W–129–B with the tool dowel pins seated in the locating holes (Fig. 16). Install the hold down clamps and tighten the tool turnbuckle finger–tight.
(2) Install a pilot stud at the left side of the differential housing. Attach Dial Indicator to housing pilot stud. Load the indicator plunger against the opposite side of the housing (Fig. 16) and zero the indicator.
CAUTION: Do not spread over 0.38 mm (0.015 in). If the housing is over–separated, it could be distorted or damaged.
(3) Separate the housing enough to install the case in the housing. Measure the distance with the dial indicator (Fig. 16).
(4) Remove the dial indicator. (5) Install differential and outboard shim/spacer (selected thickness) in housing.
(6) Install case in the housing. Tap the differential case to ensure the bearings are fully seated (Fig. 18). Remove the spreader.
(7) Install the bearing caps at their original locations (Fig. 19). Tighten the bearing cap bolts to 77 N·m (57 ft. lbs.) torque.
DIFFERENTIAL SIDE BEARINGS
REMOVAL
(1) Remove Differential case from axle housing. (2) Remove the bearings from the differential case with Press 938, and Adapter 1130 (Fig. 20).
DIFFERENTIAL SIDE BEARING INSTALLATION
If ring and pinion gears have been replaced, verify differential side bearing preload and gear mesh backlash.
(1) Using tool C-4340 with handle C-4171, install differential side bearings (Fig. 21).
(2) Install differential in axle housing.
RING GEAR
The ring and pinion gears are service in a matched set. Do not replace the ring gear with replacing the pinion gear. Refer to Pinion Gear removal and installation paragraph in this section for proper procedure.
REMOVAL
(1) Remove differential from axle housing. (2) Place differential case in a suitable vise with soft metal jaw protectors. (Fig. 22)
(3) Remove bolts holding ring gear to differential case.
(4) Using a soft hammer, drive ring gear from differential case (Fig. 22).
RING GEAR INSTALLATION
CAUTION: Do not reuse the bolts that held the ring gear to the differential case. The bolts can fracture causing extensive damage.
(1) Invert the differential case and start two ring gear bolts. This will provide case–to–ring gear bolt hole alignment.
(2) Install new ring gear bolts and alternately tighten to 95–122 N·m (70–90 ft. lbs.) torque (Fig. 23). (3) Install differential in axle housing and verify gear mesh and contact pattern.
PINION GEAR
REMOVAL
(1) Remove differential assembly from axle housing.
(2) Remove the pinion yoke nut and washer. Use Remover C–452 and Wrench C–3281 to remove the pinion yoke (Fig. 24).
(3) Remove the pinion gear from housing (Fig. 25). Catch the pinion with your hand to prevent it from falling and being damaged.
(4) Remove the pinion gear seal with a slide hammer or pry out with bar.
(5) Remove oil slinger, front bearing. (6) Remove the front pinion bearing cup and seal with Remover D-103 and Handle C–4171 (Fig. 26).
(7) Remove the rear bearing cup from housing (Fig. 27). Use Remover C-4307 and Handle C–4171.
(8) Remove the collapsible preload spacer (Fig. 28).
(9) Remove the inner bearing from the pinion with Puller C–293PA and Adapter C–293–39 (Fig. 29).
Place adapter rings so they do not damage the bearing cage.
(10) Remove the depth shims from the pinion gear shaft. Record the thickness of the depth shims.
PINION GEAR INSTALLATION
(1) Install the pinion rear bearing cup with Installer C—4308 and Driver Handle C–4171 (Fig. 30). Ensure cup is correctly seated.
(2) Install the pinion front bearing cup with Installer D–129 and Handle C–4171 (Fig. 31).
(3) Install pinion front bearing, oil slinger. Apply a light coating of gear lubricant on the lip of pinion seal. Install seal with Installer D–163 and Handle C–4171 (Fig. 32).
NOTE: Pinion depth shims are placed between the rear pinion bearing cone and pinion gear to achieve proper ring and pinion gear mesh. If the factory installed ring and pinion gears are reused, the pinion depth shim should not require replacement. Refer to Pinion Gear Deptht paragraph in this section to select the proper thickness shim before installing rear pinion bearing cone.
(4) Place the proper thickness depth shim on the pinion gear and install the rear bearing.
(5) Install the rear bearing (and slinger if used) on the pinion gear with Installer 6448 (Fig. 33).
(6) Install a new collapsible preload spacer on pinion shaft and install pinion gear in housing (Fig. 34).
(7) Install yoke with Installer W–162D and Wrench 6719 (Fig. 35).
(8) Install the yoke washer and a new nut on the pinion gear. Tighten the nut to 298 N·m (220 ft. lbs.) minimum. Do not over–tighten. Maximum torque is 380 N·m (280 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. The torque sequence will have to be repeated.
(9) Use Flange Wrench 6719 to retain the yoke (Fig. 36). Slowly tighten the nut in small increments until the rotating torque is achieved. Measure the preload torque frequently to avoid over–tightening the nut.
(10) Check bearing preload torque with an inch pound torque wrench (Fig. 37). The torque necessary to rotate the pinion gear should be:
• Original Bearings — 1 to 3 N·m (10 to 20 in. lbs.).
• New Bearings — 2 to 5 N·m (15 to 35 in. lbs.).
FINAL ASSEMBLY
(1) Install the axle shafts. Refer to Axle Shaft Installation within this group.
(2) Scrape the residual sealant from the housing and cover mating surfaces. Clean the mating surfaces with mineral spirits. Apply a bead of Mopar Silicone Rubber Sealant on the housing cover (Fig. 38). Allow the sealant to cure for a few minutes.
Install the housing cover within 5 minutes after applying the sealant.
(3) Install the cover on the differential with the attaching bolts. Install the identification tag. Tighten the cover bolts to 41 N·m (30 ft. lbs.) torque.
CAUTION: Overfilling the differential can result in lubricant foaming and overheating.
(4) Refill the differential housing with the specified quantity of Mopar Hypoid Gear Lubricant.
(5) Install the fill hole plug and tighten to 34 N·m (25 ft. lbs.) torque. Axles equipped with rubber fill plug install plug into cover.
DISASSEMBLY AND ASSEMBLY
STANDARD DIFFERENTIAL
DISASSEMBLE
(1) Remove pinion gear mate shaft. (2) Rotate the differential side gears and remove the pinion mate gears and thrust washers (Fig. 39).
(3) Remove the differential side gears and thrust washers.
DIFFERENTIAL ASSEMBLE
(1) Differential side gears and thrust washers (2) Pinion gears and thrust washers (3) Pinion gear mate shaft (align holes in shaft and case)
(4) Lubricate all differential components with hypoid gear lubricant.
(5) Install differential case in axle housing. Refer to Differential removal and installation procedure.
TRAC-LOK DIFFERENTIAL
The Trac–Lok (limited–slip) differential components are illustrated in (Fig. 40). Refer to this illustration during repair service.
DISASSEMBLY
Service to the Trac–Lok differential requires the use of Tool Set C–4487 (J–23781). Refer to Model 44 Axle section in this Group for Differential Removal and Installation.
(1) Clamp Side Gear Holding Tool 6963 in a vise. (2) Position the differential case on the holding tool (Fig. 41). Place shop towels under the differential to avoid damage if removal of the ring gear is required (Fig. 41).
(3) If ring gear replacement is required, remove and discard the bolts holding the ring gear to the case. Tap the ring gear with a rawhide or plastic mallet and separate ring gear from case (Fig. 42).
(4) Remove the pinion gear mate shaft lock screw (Fig. 43).
(5) Remove the pinion gear mate shaft. If necessary, use a drift and hammer (Fig. 44).
(6) Install and lubricate Step Plate C–4487–1 (Fig. 45).
(7) Assemble Threaded Adapter C–4487–3 into top side gear. Thread forcing Screw C–4487–2 into adapter until it becomes centered in adapter plate.
(8) Position a small screw driver in slot of Threaded Adapter C–4487–3 (Fig. 46) to prevent adapter from turning.
(9) Tighten forcing screw tool 122 N·m (90 ft. lbs.) (maximum) to compress Belleville springs in clutch packs (Fig. 47).
(10) Using a 0.020 in. feeler gauge and mallet, remove thrust washers from behind the pinion gears (Fig. 48).
(11) Loosen the forcing screw tool until the clutch pack tension is relieved and the pinion gears can be slightly rattled between the case and side gears.
(12) Insert Turning Bar C–4487–4 in case. Rotate case with tool until pinion gears can be removed (Fig. 49).
(13) Remove top side gear and clutch pack. Keep plates in correct order during removal (Fig. 50).
(14) Remove case from fixture. Remove remaining clutch pack.
(15) Remove clutch pack retaining clips. Mark each clutch pack for installation reference.
ASSEMBLY
The clutch discs are replaceable as complete sets only. If one clutch disc pack is damaged, both packs must be replaced.
Lubricate each component with gear lubricant before assembly.
(1) Assemble the clutch discs into packs secure disc packs with retaining clips (Fig. 51).
(2) Position assembled clutch disc packs on the side gear hubs.
(3) Position case on axle fixture. (4) Install clutch pack and side gear in lower bore (Fig. 52). Be sure clutch pack retaining clips remain in position and are seated in the case pockets.
(5) Install lubricated Step Plate C–4487–1 on first clutch pack (Fig. 53).
Installation
(6) Install the upper side gear and clutch disc pack (Fig. 53).
(7) Hold assembly in position. Insert Threaded Adapter C–4487–3 into top side gear, insert forcing Screw C–4487–2.
(8) Tighten forcing screw tool to slightly compress clutch discs.
(9) Place pinion gears in position in side gears and verify that mate shaft hole line up.
(10) Rotate case with Turning Bar C–4487–4 until mate shaft holes in pinion gears align with holes in case.
(11) Tighten forcing screw to 122 N·m (90 ft. lbs.) to compress the Belleville springs. Lubricate and install thrust washers behind pinion gears and align washers with a small screw driver. Insert mate shaft into each pinion gear to verify alignment.
(12) Remove forcing screw, threaded adapter and step plate. Install pinion gear mate shaft, align holes in shaft and case.
(13) Install the pinion mate shaft lock screw finger tight to hold shaft during installation.
If replacement gears and thrust washers were installed, it is not necessary to measure the gear backlash. Correct fit is due to close machining tolerances during manufacture.
(14) Lubricate all differential components with hypoid gear lubricant.
CLEANING AND INSPECTION
AXLE COMPONENTS
Wash differential components with cleaning solvent and dry with compressed air. Do not steam clean the differential components.
Wash bearings with solvent and towel dry, or dry with compressed air. DO NOT spin bearings with compressed air. Cup and bearing must be replaced as matched sets only.
Clean axle shaft tubes and oil channels in housing. Inspect for; • Smooth appearance with no broken/dented surfaces on the bearing rollers or the roller contact surfaces
• Bearing cups must not be distorted or cracked • Machined surfaces should be smooth and without any raised edges
• Raised metal on shoulders of cup bores should be removed with a hand stone
• Wear and damage to pinion gear mate shaft, pinion gears, side gears and thrust washers. Replace as a matched set only.
• Ring and pinion gear for worn and chipped teeth • Ring gear for damaged bolt threads. Replaced as a matched set only.
• Pinion yoke for cracks, worn splines, pitted areas, and a rough/corroded seal contact surface. Repair or replace as necessary.
• Preload shims for damage and distortion. Install new shims if necessary.
TRAC-LOK
(1) Clean all components in cleaning solvent. Dry components with compressed air.
(2) Inspect clutch pack plates for wear, scoring or damage. Replace both clutch packs if any one component in either pack is damaged.
(3) Inspect side and pinion gears. Replace any gear that is worn, cracked, chipped or damaged.
(4) Inspect differential case and pinion shaft. Replace if worn or damaged.
PRESOAK PLATES AND DISC
Plates and discs with fiber coating (no grooves or lines) must be presoaked in Friction Modifier before assembly. Soak plates and discs for a minimum of 20 minutes. Add remaining Friction Modifier to differential after assembly.
ADJUSTMENTS
PINION GEAR DEPTH
GENERAL INFORMATION
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. 54). 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 center line of the ring gear to the back face of the pinion is 96.8 mm (3.813 inches) for Model 44 axles. The standard depth provides the best teeth contact pattern. Refer to Backlash and Contact Pattern Analysis Paragraph in this section for additional information.
NOTE: The button end on the pinion gear head is no longer a machined–to–specifications surface. Do not use this surface for pinion depth setup or checking (Fig. 55).
Compensation for pinion depth variance is achieved with select shims. The shims are placed under the inner pinion bearing cone (Fig. 56).
If a new gear set is being installed, note the depth variance etched into both the original and replacement pinion gear. Add or subtract the thickness of the original depth shims to compensate for the difference in the depth variances. Refer to the Depth Variance charts.
Note where Old and New Pinion Marking columns intersect. Intersecting figure represents plus or minus amount needed.
For example, if old pinion is plus (+) 1 and the new pinion is minus (–) 3, intersecting figure is (+) 0.004 in. (0.10 mm). Add this amount to the original shim.
Or if the old pinion is (–) 3 and the new pinion is (–) 2, intersecting figure is (–) 0.001 in. (0.025 mm). Subtract this amount from original shim. Refer to the Pinion Gear Depth Variance Chart.
PINION DEPTH MEASUREMENT AND ADJUSTMENT
Pinion gear depth measurement is necessary when;
• Axle housing or differential case is replaced • Pinion select shim pack is unknown • Ring and pinion gears are replaced Measurements are taken with pinion cups and pinion bearings installed in housing. Take measurements with Pinion Gauge Set 6955, Pinion Block 6734 and Dial Indicator C–3339 (Fig. 57). (1) Assemble Pinion Gauge Set, Pinion Block and pinion bearings. Install assembly into differential pinion gear bore and hand tighten cone (Fig. 58).
(2) Place Arbor Disc 6928 on Arbor D–115–3 and position in the bearing cradles (Fig. 59). Install dif-
PINION GEAR DEPTH VARIANCE
ferential bearing caps on Arbor Discs and tighten caps snug only.
Arbor Discs have different steps to fit other axle sizes. Pick correct size step for axle being serviced.
(3) Firmly place Scooter Block D-115–2 and Dial Indicator on pinion height block tool and zero the dial indicator pointer.
(4) Slide the Scooter Block across the arbor while observing indicator (Fig. 60). Record the longest travel distance, whether inward (–) or outward (+), indicated by the pointer.
The plunger travel distance indicated, plus or minus the variance etched in the gear is the required thickness for the depth shims.
(5) Measure the thickness of each depth shim with a micrometer and combine the shims necessary for total required shim pack thickness.Include oil slinger or baffle thickness with the total shim pack thickness.
(6) Remove the measurement tools from the differential housing.
DIFFERENTIAL BEARING PRELOAD AND GEAR LASH
DIFFERENTIAL SHIM PACK MEASUREMENT
NOTE: It is recommended whenever bearings are removed that they be replaced.
(1) Install dummy side bearings 6929 on differential.
(2) Install the differential case in the axle housing. (3) Install the outboard shim/spacer (selected thickness) on each side between bearing cup and housing (Fig. 61). Use 0.142 in. (3.6 mm) as a starting point, shim/spacers are available in various thicknesses.
(4) Install the marked bearing caps in their correct positions. Install and snug the bolts.
(5) Attach a dial indicator to the housing. Position the indicator plunger so that it contacts the ring gear mating surface (Fig. 62).
(6) Pry the differential case to one side and zero the dial indicator pointer.
(7) Pry the differential case to the opposite side and record indicator reading. Reading is additional shim thickness needed for zero end play. For example, if reading was 0.008 in. (0.20 mm), an additional 0.004–in. (0.10 mm) thick shim will be needed at each side zero end play.
(8) Install zero end–play shims on each side of case.
The differential bearings must be preloaded to compensate for heat and load during operation.
(9) Add an additional 0.004–in. (0.1 mm) to each outboard shim/spacer for bearing preload.
(10) Remove differential from axle housing. (11) Remove dummy bearings. (12) Install new side bearing cones and cups. (13) Install ring gear. (14) Install differential and verify gear lash and contact pattern.
(15) Proceed to Final Assembly paragraph in this section.
GEAR BACKLASH AND CONTACT PATTERN ANALYSIS
After installing new side bearings or ring and pinion set adjusting the bearing perload and gear mash backlash will be necessary.
(1) Rotate assembly several revolutions to seat bearings. Measure backlash at three equally spaced locations around the perimeter of the ring gear with a dial indicator (Fig. 63).
The ring gear backlash must be within 0.12 – 0.20 mm (0.005 – 0.008 in.). It cannot vary more than 0.05 mm (0.002 in.) between the points checked.
If backlash must be adjusted, spacers are available in various thicknesses. Adjust the backlash accordingly (Fig. 64). Do not increase the total shim pack thickness, excessive bearing preload and damage will occur.
The ring gear teeth contact patterns will show if the pinion gear depth shim(s) have the correct thickness. It will also show if the ring gear backlash has been adjusted correctly. The backlash must be maintained within the specified limits until the correct tooth contact patterns are obtained.
(2) Apply a thin coat of hydrated ferric oxide, or equivalent, to the drive and coast side of the ring gear teeth.
(3) Rotate the ring gear one complete revolution in both directions while a load is being applied. Insert a pry bar between the differential housing and the case flange. This will produce distinct contact patterns on both the drive side and coast side of the ring gear teeth.
(4) Note patterns in compound. Refer to (Fig. 65) for interpretation of contact patterns and adjust accordingly.
SPECIFICATIONS
MODEL 44 AXLE
DESCRIPTION SPEC. Type . . . . . . . . . . . . . . . . . . . . .Semi-floating Hypoid Axle Ratios. . . . . . . . . . . . . . . . . . . . . . . . .3.55/3.73 Ring Gear Diameter . . . . . . . . . . .216 mm (8.5 in.) Gear Backlash . . . .0.13–0.20 mm (0.005–0.008 in.) Pinion Depth . . . . . . . . . . . . .109.52 mm (4.312 in.) Brg. Perload, Pinion (New) . . . . . . .2.26–4.52 N·m
(20–40 in. lbs.) Maximum Carrier Spread. . . . .0.51 mm (0.020 in.
TORQUE
DESCRIPTION TORQUE Bolts, Diff. Cover . . . . . . . . . . . . .41 N·m (30 ft. lbs.) Bolts, Diff. Bearing Cap . . . . . . . .85 N·m (63 ft. lbs.) Bolts, Ring Gear . . . . . . . . . . . . .108 N·m (80 ft. lbs.) Screw, ABS Sensor. . . . . . . . . . . . .8 N·m (70 in. lbs.) Nuts, Brake Backing Plate . . . . . 61 N·m (45 ft. lbs.) Nut, Pinion Gear Minimum . . .298 N·m (220 ft. lbs.)
SPECIAL TOOLS
MODEL 44 AXLE
Remover—C-452
Remover—C-4307
Installer—C-4308
Pilot—C-3288
Dial Indicator—C-3339
Trac-lok Tool Set—C-4487
Installer—D-163
Installer—D-129
Remover—D-103
Installer—W-162–D
Splitter—1130
Remover—6310
Installer—6436
Installer—6437
Installer—6448
Holder—6719
Adapter—6790
Pinion Depth Set—6955
Adapter Set—6956
Holder—6963
Remover—7794-A
Mopart Hypoid Gear Lubricant conforms to all of these specifications.
• The lubricant should have MIL–L–2105C and API GL 5 quality specifications.
• Lubricant is a thermally stable SAE 80W–90 gear lubricant.
• Lubricant for axles intended for heavy-duty or trailer tow use is SAE 75W–140 SYNTHETIC gear lubricant.
Trac-lok differentials require the addition of 4 oz. of friction modifier to the axle lubricant. The Dana 44 rear axle lubricant capacity is 2.25 L (4.75 pts.) total, including the friction modifier if necessary.
CAUTION: If axle is submerged in water, lubricant must be replaced immediately to avoid possible premature axle failure.
DESCRIPTION AND OPERATION
STANDARD DIFFERENTIAL
The differential gear system divides the torque between the axle shafts. It allows the axle shafts to rotate at different speeds when turning corners.
Each differential side gear is splined to an axle shaft. The pinion gears are mounted on a pinion mate shaft and are free to rotate on the shaft. The pinion gear is fitted in a bore in the differential case and is positioned at a right angle to the axle shafts.
In operation, power flow occurs as follows: • The pinion gear rotates the ring gear • The ring gear (bolted to the differential case) rotates the case
• The differential pinion gears (mounted on the pinion mate shaft in the case) rotate the side gears
• The side gears (splined to the axle shafts) rotate the shafts
During straight-ahead driving, the differential pinion 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 in order to complete a turn. The difference must be compensated for in order 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.
TRAC-LOK OPERATION
In a conventional differential, if one wheel spins, the opposite wheel will generate only as much torque as the spinning wheel.
In the Trac-lok differential, part of the ring gear torque is transmitted through clutch packs which contain multiple discs. The clutches will have radial grooves on the plates, and concentric grooves on the discs or bonded fiber material that is smooth in appearance.
In operation, the Trac-lok clutches are engaged by two concurrent 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. 4).
The Trac-lok design 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-lok differentials resist wheel spin 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-lok operation is normal. In extreme cases of differences of traction, the wheel with the least traction may spin.
DIAGNOSIS AND TESTING
GEAR NOISE
Axle gear noise can be caused by insufficient lubricant, incorrect backlash, tooth contact, or worn/damaged gears.
Gear noise usually happens at a specific speed range. The range is 30 to 40 mph, or above 50 mph. The noise can also occur during a specific type of driving condition. These conditions are acceleration, deceleration, coast, or constant load.
When road testing, accelerate 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:
• Check for insufficient lubricant. • Incorrect ring gear backlash. • Gear damage. Differential side and pinion gears can be checked by turning the vehicle. They usually do not cause noise in straight–ahead driving. The side gears are loaded during vehicle turns. If noise does occur during vehicle turns, the side or pinion gears could be worn or damaged. A worn pinion gear mate shaft can also cause a snapping or a knocking noise.
BEARING NOISE
The axle shaft, differential and pinion gear bearings can all produce noise when worn or damaged. Bearing noise can be either a whining, or a growling sound.
Pinion gear bearings have a constant–pitch noise. This noise changes only with vehicle speed. Pinion bearing noise will be higher because it rotates at a faster rate. Drive the vehicle and load the differential. 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 produce a low pitch noise. Differential bearing noise is similar to pinion bearing noise. The pitch of differential 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 gear shaft bore will also cause low speed knock.
VIBRATION
Vibration at the rear of the vehicle is usually caused by a:
• Damaged drive shaft. • Missing drive shaft balance weight(s). • Worn or out–of–balance wheels. • Loose wheel lug nuts. • Worn U–joint(s). • Loose/broken springs. • Damaged axle shaft bearing(s). • Loose pinion gear nut. • Excessive pinion yoke run out. • Bent 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, brackets and drive belts.
All driveline components should be examined before starting any repair.
Refer to Group 22, Wheels and Tires, for additional information.
DRIVELINE SNAP
A snap or clunk noise when the vehicle is shifted into gear (or the clutch engaged), can be caused by:
• High engine idle speed
• Loose engine/transmission/transfer case mounts • Worn U–joints • Loose spring mounts • Loose pinion gear nut and yoke • Excessive ring gear backlash • Excessive side gear/case clearance The source of a snap or a clunk noise can be determined with the assistance of a helper. Raise the vehicle 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.
TRAC–LOK DIFFERENTIAL NOISE
The most common problem is a chatter noise when turning corners. Before removing a Trac-lok unit for repair, drain, flush and refill the axle with the specified lubricant. Refer to Lubricant change in this Group.
A container of Mopart Trac-lok Lubricant (friction modifier) should be added after repair service or a lubricant change.
After changing the lubricant, drive the vehicle and make 10 to 12 slow, figure–eight turns. This maneuver will pump lubricant through the clutches. This will correct the condition in most instances. If the chatter persists, clutch damage could have occurred.
WHEEL NOISE 1. Wheel loose. 1. Tighten loose nuts.
2. Faulty, brinelled wheel bearing. 2. Faulty or brinelled bearings must be replaced.
AXLE SHAFT NOISE 1. Misaligned axle shaft tube. 1. Inspect axle shaft tube alignment. Correct as necessary.
2. Bent or sprung axle shaft. 2. Replace bent or sprung axle shaft.
3. End play in drive pinion 3. Refer to Drive Pinion Bearing Pre-Load Adjustment.
bearings.
A. Excessive gear backlash 4. Check adjustment of ring gear backlash and pinion gear.
; between ring gear and pinion Correct as necessary.
gear.
5. Improper adjustment of drive 5. Adjust drive pinion shaft bearings.
pinion gear shaft bearings.
6. Loose drive pinion gearshaft 6. Tighten drive pinion gearshaft yoke nut with specified torque.
yoke nut.
7. Improper wheel bearing 7. Readjust as necessary.
adjustment.
8. Scuffed gear tooth contact 8. If necessary, replace scuffed gears.
surfaces.
AXLE SHAFT BROKE 1. Misaligned axle shaft tube. 1. Replace broken axle shaft after correcting axle shaft tube
alignment.
2. Vehicle overloaded. 2. Replace broken axle shaft. Avoid excessive weight on vehicle.
3. Erratic clutch operation. 3. Replace broken axle shaft after inspecting for other possible
causes. Avoid erratic use of clutch.
4. Grabbing clutch. 4. Replace broken axle shaft. Inspect clutch and make necessary
repairs or adjustments.
| DIFFERENTIAL CASE 1. Improper adjustment of 1. Replace cracked case; examine gears and bearings for possible
CRACKED differential bearings. damage. At reassembly, adjust differential bearings properly.
2. Excessive ring gear backlash. 2. Replace cracked case; examine gears and bearings for possible
damage. At reassembly, adjust ring gear backlash properly.
3. Vehicle overloaded. 3. Replace cracked case; examine gears and bearings for possible
damage. Avoid excessive weight on vehicle.
A. Erratic clutch operation. 4, Replace cracked case. After inspecting for other possible
causes, examine gears and bearings for possible damage.
Avoid erratic use of clutch.
DIFFERENTIAL GEARS 1. Insufficient lubrication. 1. Replace scored gears. Scoring marks on the drive face of gear
SCORED teeth or in the bore are caused by instantaneous fusing of the
mating surfaces. Scored gears should be replaced. Fill rear
differential housing to required capacity with proper lubricant.
Refer to Specifications.
2. Improper grade of lubricant. 2. Replace scored gears. Inspect all gears and bearings for
possible damage. Clean and refill differential housing to
required capacity with proper lubricant.
3. Excessive spinning of one 3. Replace scored gears. Inspect all gears, pinion bores and shaft
wheelltire. for damage. Service as necessary.
LOSS OF LUBRICANT 1. Lubricant level too high. 1. Drain excess lubricant by removing fill plug and allow lubricant
to level at lower edge of fill plug hole.
LOSS OF LUBRICANT 2. Worn axle shaft seals. 2. Replace worn seals.
3. Cracked differential housing. 3. Repair or replace housing as necessary.
4. Worn drive pinion gear shaft 4. Replace worn drive pinion gear shaft seal.
seal.
5. Scored and worn yoke. 5. Replace worn or scored yoke and seal.
6. Axle cover not properly sealed. 6. Remove cover and clean flange and reseal.
AXLE OVERHEATING 1. Lubricant level too low. 1. Refill differential housing.
2. Incorrect grade of lubricant. 2. Drain, flush and refill with correct amount of the correct
lubricant.
3. Bearings adjusted too tight. 3. Readjust bearings.
4. Excessive gear wear. 4. Inspect gears for excessive wear or scoring. Replace as
necessary.
5. Insufficient ring gear backlash. 5. Readjust ring gear backlash and inspect gears for possible
scoring.
GEAR TEETH BROKE 1. Overloading. 1. Replace gears. Examine other gears and bearings for possible
(RING GEAR AND PINION) damage.
2. Erratic clutch operation. 2. Replace gears and examine the remaining parts for possible
damage. Avoid erratic clutch operation.
3. Ice-spotted pavements. 3. Replace gears. Examine the remaining parts for possible
damage. Replace parts as required.
4. Improper adjustments. 4. Replace gears. Examine other parts for possible damage.
Ensure ring gear backlash is correct.
AXLE NOISE 1. Insufficient lubricant. 1. Refill axle with correct amount of the proper lubricant.
Also inspect for leaks and correct as necessary.
2. Improper ring gear and drive 2. Check ring gear and pinion gear teeth contact pattern.
pinion gear adjustment.
3. Unmatched ring gear and drive 3. Remove unmatched ring gear and drive pinion gear.
pinion gear. Replace with matched gear and drive pinion gear set.
4. Worn teeth on ring gear or 4. Check teeth on ring gear and drive pinion gear for correct
drive pinion gear. contact. If necessary, replace with new matched set.
5. Loose drive pinion gear shaft 5. Adjust drive pinion gearshaft bearing preload torque.
bearings.
6. Loose differential bearings. 6. Adjust differential bearing preload torque.
7. Misaligned or sprung ring gear. 7. Measure ring gear runout.
8. Loose differential bearing cap 8. Tighten with specified torque
bolts
J9503-4
TRAC–LOK TEST
WARNING: WHEN SERVICING VEHICLES WITH A TRAC–LOK DIFFERENTIAL DO NOT USE THE ENGINE TO TURN THE AXLE AND WHEELS. BOTH REAR WHEELS MUST BE RAISED AND THE VEHI- CLE SUPPORTED. A TRAC–LOK AXLE CAN EXERT ENOUGH FORCE IF ONE WHEEL IS IN CONTACT WITH A SURFACE TO CAUSE THE VEHICLE TO MOVE.
The differential can be tested without removing the differential case by measuring rotating torque. Make sure brakes are not dragging during this measurement.
(1) Place blocks in front and rear of both front wheels.
(2) Raise one rear wheel until it is completely off the ground.
(3) Engine off, transmission in neutral, and parking brake off.
(4) Remove wheel and bolt Special Tool 6790 to studs.
(5) Use torque wrench on special tool to rotate wheel and read rotating torque (Fig. 5).
(6) If rotating torque is less than 22 N·m (30 ft. lbs.) or more than 271 N·m (200 ft. lbs.) on either wheel the unit should be serviced.
SERVICE PROCEDURES
LUBRICANT CHANGE
(1) Raise and support the vehicle. (2) Remove the lubricant fill hole plug from the differential housing cover.
(3) Remove the 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 the original sealant from the housing and cover surfaces.
(6) Apply a bead of Mopart Silicone Rubber Sealant, or equivalent, to the housing cover (Fig. 6).
Install the housing cover within 5 minutes after applying the sealant.
(7) Install the cover and any identification tag. Tighten the cover bolts to 41 N·m (30 ft. lbs.) torque.
(8) For Trac–Lok differentials, a quantity of Mopart Trac–Lok lubricant (friction modifier), or equivalent, must be added after repair service or a lubricant change. Refer to the General Information section of this group for the quantity necessary.
(9) Fill differential with Mopart Hypoid Gear Lubricant, or equivalent, to bottom of the fill plug hole. Refer to the Lubricant Specifications in this group for the quantity necessary.
CAUTION: Overfilling the differential can result in lubricant foaming and overheating.
(10) Install the fill hole plug and lower the vehicle. (11) Trac–Lok differential equipped vehicles should be road tested by making 10 to 12 slow figure-eight turns. This maneuver will pump the lubricant through the clutch discs to eliminate a possible chatter noise complaint.
REMOVAL AND INSTALLATION
REAR AXLE
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) Remove the brake rotors and calipers from the axle. Refer to Group 5, Brakes, for proper procedures.
(6) Disconnect the vent hose from the axle shaft tube.
(7) Mark the propeller shaft and yokes for installation alignment reference.
(8) Remove propeller shaft. (9) Disconnect stabilizer bar links. (10) Disconnect shock absorbers from axle. (11) Disconnect track bar. (12) Disconnect upper and lower suspension arms from the axle brackets.
(13) Separate the axle from the vehicle.
INSTALLATION
NOTE: The weight of the vehicle must be supported by the springs before suspension arms and track bar fasteners can be tightened. If the springs are not at their normal ride position, vehicle ride height and handling could be affected.
(1) Raise the axle with lifting device and align coil springs.
(2) Position the upper and lower suspension arms on the axle brackets. Install nuts and bolts, do not tighten bolts at this time.
(3) Install track bar and attachment bolts, do not tighten bolts at this time.
(4) Install shock absorber and tighten nuts to 60 N·m (44 ft. lbs.) torque
(5) Install stabilizer bar link and tighten nuts to 36 N·m (27 ft. lbs.) torque (6) Install the brake rotors and calipers. Refer to Group 5, Brakes, for proper procedures.
(7) Install axle vent hose (8) Align propeller shaft and pinion yoke reference marks. Install U-joint straps and bolts tighten to 19 N·m (14 ft. lbs.) torque
(9) Install the wheels and tires. (10) Check and add gear lubricant. (11) Remove lifting device from axle and lower the vehicle.
(12) Tighten lower suspension arms bolts to 177 N·m (130 ft. lbs.) torque.
(13) Tighten upper suspension arms bolts to 75 N·m (55 ft. lbs.) torque.
(14) Tighten track bar bolts to 100 N·m (74 ft. lbs.) torque.
PINION SHAFT SEAL REPLACEMENT
REMOVAL
(1) Raise and support the vehicle. (2) Remove wheel and tire assemblies. (3) Remove rear brake rotors and calipers. Refer to Group 5, Brakes, for proper procedures.
(4) Mark the propeller shaft and pinion yoke for installation reference.
(5) Remove the propeller shaft from the yoke. (6) Rotate the pinion gear three or four times. (7) Measure the amount of torque necessary to rotate the pinion gear with an (in. lbs.) dial-type torque wrench. Record the torque reading for installation reference.
(8) Using a short piece of pipe and Holder 6958 to hold the pinion yoke, remove the pinion nut and washer (Fig. 7).
(9) Use Remover C-452 and Wrench C-3281 to remove the pinion yoke (Fig. 8).
(10) Use Remover 7794A and slide hammer to remove the pinion shaft seal (Fig. 9).
INSTALLATION
(1) Apply a light coating of gear lubricant on the lip of pinion seal. Install seal with Installer D-163 and Handle C-4171 (Fig. 10).
(2) Install yoke on the pinion gear with Installer C-3718.
CAUTION: Do not exceed the minimum tightening torque when installing the pinion yoke retaining nut at this point. Damage to collapsible spacer or bearings may result.
(3) Install a new nut on the pinion gear. Tighten the nut only enough to remove the shaft end play.
(4) Rotate the pinion shaft using an (in. lbs.) torque wrench. Rotating resistance torque should be equal to the reading recorded during removal, plus an additional 0.56 N·m (5 in. lbs.) (Fig. 11).
(5) If the rotating torque is low, use Holder 6958 to hold the pinion yoke (Fig. 12), and tighten the pinion shaft nut in 6.8 N·m (5 ft. lbs.) increments until proper rotating torque is achieved.
CAUTION: If the maximum tightening torque is reached prior to reaching the required rotating torque, the collapsible spacer may have been damaged. Replace the collapsible spacer.
(6) Align the installation reference marks and install the propeller shaft.
(7) Add gear lubricant to the differential housing, if necessary. Refer to the Lubricant Specifications for gear lubricant requirements.
(8) Install brake rotors and calipers. Refer to Group 5, Brakes, for proper procedures.
(9) Install wheel and tire assemblies. (10) Lower the vehicle.
COLLAPSIBLE SPACER
REMOVAL W/PINION INSTALLED
(1) Raise and support the vehicle. (2) Remove wheel and tire assemblies. (3) Remove rear brake rotors and calipers. Refer to Group 5, Brakes, for proper procedures.
(4) Mark the propeller shaft and pinion yoke for installation reference.
(5) Remove the propeller shaft from the yoke. (6) Rotate the pinion gear three or four times. (7) Measure the amount of torque necessary to rotate the pinion gear with an in. lbs. dial-type torque wrench. Record the torque reading for installation reference.
(8) Using a short piece of pipe and Holder 6958 to hold the pinion yoke, remove the pinion nut and washer (Fig. 13).
(9) Use Remover C-452 and Wrench C-3281 to remove the pinion yoke (Fig. 14).
(10) Use Remover 7794-A and slide hammer to remove the pinion shaft seal (Fig. 15).
(11) Remove the front pinion bearing using a pair of suitable pick tools to pull the bearing straight off the pinion gear shaft. It may be necessary to lightly tap the end of the pinion gear with a rawhide or rubber mallet if the bearing becomes bound on the pinion shaft.
(12) Remove the collapsible spacer.
REMOVAL W/PINION REMOVAL
(1) Raise and support the vehicle. (2) Remove wheel and tire assemblies. (3) Remove rear brake rotors and calipers. Refer to Group 5, Brakes, for proper procedures.
(4) Mark the propeller shaft and pinion yoke for installation reference.
(5) Remove the propeller shaft from the yoke. (6) Rotate the pinion gear three or four times. (7) Measure the amount of torque necessary to rotate the pinion gear with an in. lbs. dial-type torque wrench. Record the torque reading for installation reference.
(8) Remove differential assembly from axle housing.
(9) Using Holder 6958 to hold yoke and a short length of 1 in. pipe, remove the pinion yoke nut and washer (Fig. 13).
(10) Using Remover C–452 and Wrench C–3281, remove the pinion yoke from pinion shaft (Fig. 14).
(11) Remove the pinion gear from housing (Fig. 16). Catch the pinion with your hand to prevent it from falling and being damaged.
(12) Remove collapsible spacer from pinion shaft.
INSTALLATION
(1) Install a new collapsible preload spacer on pinion shaft (Fig. 17).
(2) If pinion gear was removed, install pinion gear in housing.
(3) Install pinion front bearing. Apply a light coating of gear lubricant on the lip of pinion seal. Install seal with Installer D–163 and Handle C–4171 (Fig. 18).
(4) Install yoke with Installer C–3718 and holder 6958 (Fig. 19). (5) If the original pinion bearings are being used, install differential assembly and axle shafts, if necessary.
NOTE: If new pinion bearings were installed, do not install the differential assembly and axle shafts until after the pinion bearing preload and rotating torque are set.
(6) Install the yoke washer and a new nut on the pinion gear. Tighten the nut to 298 N·m (220 ft. lbs.) minimum. Do not over–tighten. Maximum torque is 380 N·m (280 ft. lbs.).
CAUTION: Never loosen pinion gear nut to decrease pinion gear bearing rotating torque and never exceed specified preload torque. If preload torque is exceeded a new collapsible spacer must be installed. The torque sequence will have to be repeated.
NOTE: A new collapsible spacer will start to crush at around 265 ft. lbs. torque. If the spacer requires more than 280 ft. lbs. torque to crush, the collapsible spacer is defective.
(7) Using yoke holder 6958, a short length of 1 in. pipe, and a torque wrench set at 380 N·m (280 ft. lbs.), crush collapsible spacer until bearing end play is taken up (Fig. 20).
(8) Slowly tighten the nut in 6.8 N·m (5 ft. lbs.) increments until the rotating torque is achieved.
Measure the rotating torque frequently to avoid over crushing the collapsible spacer (Fig. 21).
(9) Check rotating torque with an inch pound torque wrench (Fig. 21). The torque necessary to rotate the pinion gear should be:
• Original Bearings — The reading recorded during removal, plus an additional 0.56 N·m (5 in. lbs.).
• New Bearings — 2 to 5 N·m (15 to 35 in. lbs.).
(10) Install differential assembly and axle shafts, if necessary.
(11) Align marks made previously on yoke and propeller shaft and install propeller shaft.
(12) Install rear brake rotors and calipers. Refer to Group 5 Brakes, for proper procedures.
(13) Add gear lubricant, if necessary. Refer to Lubricant Specifications of this section for lubricant requirements.
(14) Install wheel and tire assemblies. (15) Lower vehicle.
AXLE SHAFT
REMOVAL
(1) Raise and support vehicle. Ensure that the transmission is in neutral.
(2) Remove rear wheel and tire. (3) Remove brake caliper and rotor. Refer to Group 5, Brakes, for proper procedure. (4) Clean all foreign material from housing cover area.
(5) Loosen housing cover bolts. Drain lubricant from the housing and axle shaft tubes. Remove housing cover.
(6) Rotate differential case so that pinion mate gear shaft lock screw is accessible. Remove lock screw and pinion mate gear shaft from differential case (Fig. 22).
(7) Push axle shaft inward and remove axle shaft C–clip lock from the axle shaft (Fig. 23).
(8) Remove axle shaft. Use care to prevent damage to axle shaft bearing and seal, which will remain in axle shaft tube.
(9) Inspect axle shaft seal for leakage or damage. (10) Inspect roller bearing contact surface on axle shaft for signs of brinelling, galling and pitting. If any of these conditions exist, the axle shaft and/or bearing and seal must be replaced.
INSTALLATION
(1) Lubricate bearing bore and seal lip with gear lubricant. Insert axle shaft through seal, bearing, and engage it into side gear splines. Use care to
prevent shaft splines from damaging axle shaft seal lip.
(2) Insert C–clip lock in end of axle shaft. Push axle shaft outward to seat C–clip lock in side gear.
(3) Insert pinion mate shaft into differential case and through thrust washers and pinion gears.
(4) Align hole in shaft with hole in the differential case and install lock screw with Loctitet on the threads. Tighten lock screw to 19 N·m (14 ft. lbs.) torque.
(5) Install cover and add fluid. Refer to Lubricant Change procedure in this section for procedure and lubricant requirements.
(6) Install brake caliper and rotor. Refer to Group 5, Brakes, for proper procedures. (7) Install wheel and tire. (8) Lower vehicle.
AXLE SHAFT SEAL AND BEARING
REMOVAL
(1) Remove the axle shaft. (2) Remove the axle shaft seal from the end of the axle shaft tube with a small pry bar.
NOTE: The seal and bearing can be removed at the same time with the bearing removal tool.
(3) Remove the axle shaft bearing from the tube (Fig. 24) with Bearing Removal Tool Set 6310.
(4) Inspect the axle shaft tube bore for roughness and burrs. Remove as necessary.
INSTALLATION
Do not install the original axle shaft seal. Always install a new seal.
(1) Wipe the bore in the axle shaft tube clean. (2) Install axle shaft bearing with Installer 6436 and Handle C–4171. Ensure part number on the bearing is against the installer.
(3) Install the new axle shaft seal (Fig. 25) with Installer 6437 and Handle C–4171.
(4) Install the axle shaft.
DIFFERENTIAL
REMOVAL
(1) Remove axle shafts. (2) Note the orientation of the installation reference letters stamped on the bearing caps and housing machined sealing surface (Fig. 26).
(3) Remove the differential bearing caps. (4) Position Spreader W–129–B with the tool dowel pins seated in the locating holes (Fig. 27).
(5) Install the hold down clamps and tighten the tool turnbuckle finger–tight.
(6) Install a pilot stud at the left side of the differential housing. Attach dial indicator to housing pilot stud. Load the indicator plunger against the opposite side of the housing (Fig. 27) and zero the indicator.
(7) Separate the housing enough to remove the case from the housing. Measure the distance with the dial indicator (Fig. 27).
CAUTION: Do not spread over 0.38 mm (0.015 in). If the housing is over–separated, it could be distorted or damaged.
(8) Remove the dial indicator. (9) Pry the differential case loose from the housing. To prevent damage, pivot on housing with the end of the pry bar against spreader (Fig. 28).
(10) Remove the case from housing. Mark or tag bearing cups and outboard shim(s)/spacer(s) (selected thickness) to indicate which side they were removed from.
DIFFERENTIAL INSTALLATION
(1) Position Spreader W–129–B with the tool dowel pins seated in the locating holes (Fig. 27). Install the hold down clamps and tighten the tool turnbuckle finger–tight.
(2) Install a pilot stud at the left side of the differential housing. Attach dial indicator to housing pilot stud. Load the indicator plunger against the opposite side of the housing (Fig. 27) and zero the indicator.
(3) Separate the housing enough to install the case in the housing. Measure the distance with the dial indicator (Fig. 27).
CAUTION: Do not spread over 0.51 mm (0.020 in). If the housing is over–separated, it could be distorted or damaged.
(4) Remove the dial indicator. (5) Install differential and outboard shim(s)/spacer(s) (selected thickness) in housing.
(6) Install case in the housing. Tap the differential case with a rawhide or rubber mallet to ensure the bearings are fully seated in the differential housing (Fig. 29).
(7) Remove the spreader. (8) Install the bearing caps at their original locations (Fig. 30). Tighten the bearing cap bolts to 77 N·m (57 ft. lbs.) torque.
(9) Install axle shafts.
DIFFERENTIAL SIDE BEARINGS
REMOVAL
(1) Remove differential case from axle housing. (2) Remove the bearings from the differential case with Puller/Press C-293-PA, C-293-42 Adapters and Plug C-293-3 (Fig. 31).
DIFFERENTIAL SIDE BEARING INSTALLATION
(1) Using tool C-4340 with handle C-4171, install differential side bearings (Fig. 32).
(2) Install differential case in axle housing.
RING GEAR
NOTE: The ring and pinion gears are service in a matched set. Do not replace the ring gear without replacing the pinion gear.
REMOVAL
(1) Remove differential case from axle housing. (2) Clamp Side Gear Holding Tool 6963-A in a vise. (3) Position deferential case on the holding tool (Fig. 33).
(4) Place shop towels around differential to cover vise in order to prevent damage to ring gear when removed.
(5) Remove and discard the bolts holding the ring gear to differential case.
(6) Using a soft hammer, drive ring gear from differential case.
RING GEAR INSTALLATION
CAUTION: Do not reuse the bolts that held the ring gear to the differential case. The bolts can fracture causing extensive damage.
(1) Invert the differential case on Side Gear Holding Tool 6963-A.
(2) Position ring gear on the differential case and start two new ring gear bolts. This will provide case- –to–ring gear bolt hole alignment.
(3) Invert the differential case on Side Gear Holding Tool 6963-A.
(4) Install new ring gear bolts and alternately tighten to 95–122 N·m (70–90 ft. lbs.) torque (Fig. 34). (5) Install differential in axle housing and verify differential side bearing preload, gear mesh, and contact pattern.
PINION GEAR
REMOVAL
(1) Remove differential assembly from axle housing.
(2) Mark pinion yoke and propeller shaft for installation alignment.
(3) Disconnect propeller shaft from pinion yoke. Using suitable wire, tie propeller shaft to underbody.
(4) Using Holder 6958 to hold yoke and a short length of 1 in. pipe, remove the pinion yoke nut and washer (Fig. 35).
(5) Using Remover C–452 and Wrench C–3281, remove the pinion yoke from pinion shaft (Fig. 36).
(6) Remove the pinion gear from housing (Fig. 37). Catch the pinion with your hand to prevent it from falling and being damaged.
(7) Remove the pinion seal with a slide hammer or pry out with bar.
(8) Remove oil slinger, if equipped, and the front pinion bearing.
(9) Remove the front pinion bearing cup with Remover D-103 and Handle C–4171 (Fig. 38).
(10) Remove the rear bearing cup from housing (Fig. 39). Use Remover C-4307 and Handle C–4171.