Rear Axle - 248RBI
DIAGNOSIS AND TESTINGThe most common problem is a chatter noise when turning corners. Before removing the unit for repair, drain, flush and refill the axle with the specified lubricant. A container of Mopar Trac-lok Lubricant (friction modifier) should be added after repair service or during 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.
DIFFERENTIAL TEST
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 or equivalent tool to studs.
5. Use torque wrench on special tool to rotate wheel and read rotating torque (Fig. 36).
6. If rotating torque is less than 41 Nm (56 ft. lbs.) or more than 271 Nm (200 ft. lbs.) on either wheel the unit should be serviced.
DISASSEMBLY
1. Clamp side gear Holding Fixture 6965 in a vise and position the differential case on the Holding Fixture (Fig. 37).
2. Remove ring gear if the ring gear is to be replaced. The Trac-lok differential can be serviced with the ring gear installed.
3. Remove the pinion gear mate shaft lock screw (Fig. 38).
4. Remove pinion gear mate shaft with a drift and hammer (Fig. 39).
5. Install and lubricate Step Plate C-6960-3 (Fig. 40).
6. Assemble Threaded Adapter C-6960-1 into top side gear. Thread Forcing Screw C-6960-4 into adapter until it becomes centered in adapter plate.
7. Position a small screw driver in slot of Threaded Adapter Disc C-6960-3 (Fig. 41) to prevent adapter from turning.
8. Install Forcing Screw C-6960-4 and tighten screw to 122 Nm (90 ft. lbs.) maximum to compress Belleville springs in clutch packs (Fig. 42).
9. With a feeler gauge remove thrust washers from behind the pinion gears (Fig. 43).
10. Insert Turning Bar C-6960-2 into the pinion mate shaft hole in the case (Fig. 44).
11. Loosen the Forcing Screw in small increments until the clutch pack tension is relieved and the differential case can be turned using Turning Bar.
12. Rotate differential case until the pinion gears can be removed.
13. Remove pinion gears from differential case.
14. Remove Forcing Screw, Step Plate and Threaded Adapter.
15. Remove top side gear, clutch pack retainer and clutch pack. Keep plates in correct order during removal (Fig. 45).
16. Remove differential case from the Holding Fixture. Remove side gear, clutch pack retainer and clutch pack. Keep plates in correct order during removal.
ASSEMBLY
NOTE: New 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.
1. Lubricate components with gear lubricant.
2. Assemble clutch discs into packs and secure disc packs with retaining clips (Fig. 46).
NOTE: Dished plate is position with the convex side against the side gear.
3. Position assembled clutch disc packs on the side gear hubs.
4. Install clutch pack and side gear in the ring gear side of the differential case (Fig. 47). Be sure clutch pack retaining clips remain in position and are seated in the case pockets.
5. Position the differential case on the Holding Fixture 6965.
6. Install lubricated Step Plate C-6960-3 in lower side gear (Fig. 48).
7. Install the upper side gear and clutch disc pack (Fig. 48).
8. Hold assembly in position. Insert Threaded Adapter C-6960-1 into top side gear.
9. Install Forcing Screw C-6960-4 and tighten screw to slightly compress clutch disc.
10. Place pinion gears in position in side gears and verify that the pinion mate shaft hole is aligned.
11. Rotate case with Turning Bar C-6960-2 until the pinion mate shaft holes in pinion gears align with holes in case. It may be necessary to slightly tighten the forcing screw in order to install the pinion gears.
12. Tighten forcing screw to 122 Nm (90 ft. lbs.) maximum to compress the Belleville springs.
13. 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.
14. Remove Forcing Screw, Step Plate and Threaded Adapter.
15. Install pinion gear mate shaft and align holes in shaft and case.
16. Install pinion mate shaft lock screw finger tight to hold shaft during differential installation.
17. Lubricate all differential components with hypoid gear lubricant.