Differential Assembly & Adjustment
1. Lubricate all components with rear axle lubricant, then install thrust washers on side gears and position gears in counterbores of differential.
2. Install thrust washers on pinion gears, then mesh pinion gears with side gears exactly 180 degrees apart.
3. Rotate side gears to align pinion gears and thrust washers with pinion shaft holes in case, then install pinion shaft and lock screw. Torque lock screw to 90 inch lbs.
4. If ring gear was removed, relieve sharp edge of chamfer on the inside diameter of ring gear with an Arkansas stone. This is to prevent removing metal from case during ring gear installation that may become embedded under the ring gear.
5. Install three pilot studs in case, then heat ring gear with heat lamp or by immersing the gear in hot oil. the temperature should not exceed 300 degrees F. Do not use a torch to heat ring gear.
6. Insert new ring gear attaching bolts through case flange and into ring gear, then alternately tighten bolts to 70 ft. lbs.
7. Using arbor press and suitable adapters, install bearings on differential case.
8. Position both bearing cups in axle housing bore ensuring they are not cocked, then select and install rear axle pinion setting gauge as follows:
a. On 7 1/4 inch axles, assemble pinion locating spacer SP-3244 over main body of tool SP-5385 followed by rear bearing cone. Position tool in axle housing and install shaft locating sleeve SP-3245, front bearing cone, compression sleeve SP-3194-B, centralizing washer SP-534 and compression nut SP-3193.
b. On 8 1/4 inch axles, assemble pinion locating spacer SP-6030 over main body of tool SP-5385 followed by rear bearing cone. Position tool in axle housing and install shaft locating sleeve SP-5382, front bearing cone, SP-6022 washer followed by compression sleeve SP-3194-B, centralizing washer SP-534 and compression nut SP-3193.
c. On 9 1/4 inch axles, assemble pinion locating spacer SP-6017 over main body of tool SP-526 followed by rear bearing cone. Position tool in axle housing and install front pinion bearing cone, shaft locating sleeve SP-1730, washer SP-6022, compression sleeve SP-535-A, centralizing washer SP-534 and compression nut SP-533.
9. While holding compression sleeve with tool C-3281, tighten compression nut to draw pinion bearing cups into axle housing cup bores. Allow tool to turn several revolutions during tightening operation to prevent brinnelling of bearing cups or cones.
10. Loosen compression nut, then lubricate front and rear pinion bearings with axle lubricant. Tighten compression nut until to produce 15---25 inch lbs. of rotating torque. Rotate pinion several turns to seat bearing rollers.
11. To determine pinion height, assemble tools as follows:
a. On 7 1/4 inch axles, install gauge block SP-3250 on end of main body SP-5385, then install cap screw SP-536 and tighten securely with SP-531 wrench.
b. On 8 1/4 inch axles, install gauge block SP-5383 on end of main body SP-5385, then install cap screw SP-536 and tighten securely with SP-531 wrench.
c. On 9 1/4 inch axles, install gauge block SP-6020 on end of main body SP-526, then install cap screw SP-536 and tighten securely with SP-531 wrench.
12. Position cross bore arbor in axle housing differential bearing seats. Tool numbers are as follows:
a. On 7 1/4 inch axles, use tool SP-3243.
b. On 8 1/4 inch axles, use tool SP-6029.
c. On 9 1/4 inch axles, use tool SP-6018.
13. Center arbor installed above, so that an approximate equal distance is maintained at both ends. Position a piece of 0.002 inch shim stock on arbor where bearing cap seats, then install bearing cap and bolts. Torque bolts to 10 ft. lbs.
14. Select pinion bearing mounting shim which will fit snugly between cross bore arbor and gauge block. Shims are available in 0.001 inch increments from 0.020 inch to 0.038 inch.
15. Read numbers on pinion shaft head. When number is preceded by a minus sign, add that amount to shim selected in step 14. When number is preceded by a plus sign, subtract that amount from shim selected in step 14.
Fig. 2 Exploded view of rear axle assembly. 1982---87 7-1/4 axle:
Fig. 3 Exploded view of rear axle assembly. 8-1/4& 9-1/4 axles:
16. Remove tools from axle housing, then install shim selected above.
17. Lubricate front and rear pinion bearings with suitable rear axle lubricant, then insert drive pinion and bearing assembly through axle housing. Install new collapsible spacer. Position front bearing cone over pinion stem then the companion flange and pinion nut.
18. On 7 1/4 inch and 8 1/4 axles, use companion flange holding tool C-3281 and installer C-3718 to install front pinion bearing cone on pinion stem. On 9 1/4 inch axle, use companion flange holding tool C-3281 and installer C-496 to install front pinion bearing cone on pinion stem. Use caution during front pinion bearing cone installation not to collapse spacer.
19. Remove tools used in step 18, then using suitable seal installer, install drive pinion oil seal. Seal is properly installed when seal flange contacts housing housing flange face.
20. While supporting pinion in carrier, install companion flange using tools outlined in step 18, then remove tools and install washer (convex side out) and pinion nut. Do not tighten at this time.
21. Hold companion flange with holding tool C-3281, then while occasionally rotating pinion shaft to seat bearings, tighten pinion nut just enough to remove pinion end play.
22. Remove holding tool, then rotate pinion several complete revolutions in either direction and torque pinion nut to 210 ft. lbs. Using a suitable torque wrench, measure torque required to rotate pinion and compare to specifications. If not within specifications, tighten pinion nut in small increments until proper preload is obtained. Do not back off the pinion nut for any reason. If pinion nut is backed off for any reason, a new collapsible spacer must be installed and pinion nut retightened until proper preload is obtained.
23. Apply suitable axle lubricant to differential bearings and adjusters, then position differential assembly in axle housing. Install bearing caps using marks made during disassembly for reference. Install cap bolts. Tighten top bolt to 10 ft. lbs. while tightening lower bolts finger tight.
24. Using tool C-4164, tighten bearing adjusters until bearing free play is eliminated, but with some drive gear back lash remaining. Seat bearings by rotating differential assembly. When rotating bearing adjusters, the bearing cups do not always move directly with them. To ensure accurate adjustment, always rotate differential assembly 1/2 turn in either direction five to ten times each time an adjustment is made.
25. Mount suitable dial indicator to housing case with stylus positioned against drive side of gear tooth. Find point of minimum backlash by checking backlash at four points approximately 90 degrees apart around ring gear. Rotate ring gear to position of least backlash. Mark index so all backlash readings will be taken with the same teeth in mesh.
26. Loosen right adjuster and tighten left adjuster until backlash is 0.003---0.004 inch with each adjuster tightened to 10 ft. lbs. Seat bearings as outlined above.
27. Torque bearing cap bolts to 45 ft. lbs on 7 1/4 inch axles, or 100 ft. lbs. on other axles.
Fig. 1 Hex adjuster tool installation:
28. Using tool C-4164, tighten right side adjuster to 70 ft. lbs. on 7 1/4 inch and 8 1/4 inch axles, or 75 ft. lbs. on 9 1/4 inch axles. Seat bearings as outlined above.
29. Continue to tighten right side adjuster and seat bearings until torque remains constant at 70 ft. lbs. on 7 1/4 inch and 8 1/4 inch axles, or 75 ft. lbs. on 9 1/4 inch axles.
30. Measure backlash and compare to specifications. If not within specifications, continue to increase tightening torque on right side adjuster and seat bearings until backlash is within specifications.
31. Using tool C-4164, tighten left side adjuster to 70 ft. lbs. on 7 1/4 inch and 8 1/4 inch axles, or 75 ft. lbs. on 9 1/4 inch axles. Seat bearings as outlined above.
32. Continue to tighten left side adjuster and seat bearings until torque remains constant at 70 ft. lbs. on 7 1/4 inch and 8 1/4 inch axles, or 75 ft. lbs. on 9 1/4 inch axles. If above steps were performed properly, initial torque reading should be 70 ft. lbs. on 7 1/4 inch and 8 1/4 inch axles, or 75 ft. lbs. on 9 1/4 inch axles. If torque reading is substantially less, entire procedure must be repeated.
33. Install adjuster lock screws. Torque screws to 90 inch lbs.
34. Apply thin coat of hydrated ferric oxide (yellow oxide of iron) to ring gear teeth, then with load applied at companion flange, rotate ring gear one complete revolution in both directions. This action will leave a distinct contact pattern on the ring gear teeth.
Fig. 4 Proper tooth contact:
Fig. 5 Improper tooth contact requiring thicker pinion height shim:
Fig. 6 Improper tooth contact requiring thinner pinion height shim:
35. Observe tooth contact pattern and compare to views shown. If contact pattern shows pinion mesh of depth and backlash are set properly and no further adjustments are necessary.
36. If contact pattern shows the drive pinion is too far away from ring gear centerline, a thicker pinion height shim is required.
37. If contact pattern shows the drive pinion is too close to the ring gear center line, a thinner pinion height shim is required.
38. When correct tooth contact pattern is established, install propeller shaft and axle shafts. Refer to "Propeller Shaft, Replace" and "Axle Shafts, Replace" in the "Chrysler Rear Wheel Drive Chapter" for procedures.
39. Remove axle filler plug, then using capacities listed below, fill rear axle with Multi-Purpose Axle Gear Lubricant. On axles equipped with Sure-Grip differential, 4 ounces of MOPAR Hypoid Gear Oil Additive Friction Modifier, part No. 4057100 must be included with every refill.
a. On 7 1/4 inch axles, 2.5 pints.
b. On 8 1/4 inch axles, 4.4 pints.
c. On 9 1/4 inch axles, 4.5 pints.
40. Lower vehicle and road test.