Assembly
Differential Side Bearing Preload AdjustmentSide bearing preload should be set before pinion is installed. If pinion is installed, remove ring gear.
1. Ensure bearing bores in housing and bearing caps are clean and free from burrs.
2. Measure production shims or service spacer and shim packs removed during disassembly to determine approximate thickness of shims needed for installation. Do not reuse cast iron production shims as they may break during installation. If service spacers and shims were previously installed, they can be reused.
3. In addition to .170 inch service spacers for each side and select service shim thickness required based on measurements made in step 2.
4. Place outer races over side bearings, mount differential assembly in housing and insert service spacer between each bearing race and housing with chamfered edge against housing.
5. Install left bearing cap to retain case assembly and tighten bolts hand tight so that case can be moved while checking adjustments. A bearing cap bolt can be installed in lower right bearing cap hole to prevent case from dropping while performing shim adjustments.
6. Select one or two shims totaling thickness calculated in step 3 and insert shims between right bearing cap and service spacer.
7. Insert progressively larger feeler gauges between shim and service spacer until noticeable increase in drag can be felt, pushing gauge down until it contacts housing bore to obtain proper reading. Rotate case while inserting gauges to ensure even readings.
8. The gauge used just before additional drag is felt is correct thickness to obtain ``zero preload.'' By starting with a thin gauge a sense of feel can be obtained for the original light drag caused by the weight of the case, allowing the drag caused by the beginning of preload to be recognized. It will be necessary to work case in and out and to the left in order to insert feeler gauges.
9. When the proper gauge thickness has been determined to obtain zero preload, remove bearing cap, case assembly service spacers and shim pack.
10. Select 2 service shims of approximate equal thickness whose total thickness is equal to the thickness of the shims installed in step 6 plus the thickness of the feeler gauge used to obtain zero preload.
11. Shims selected during this procedure allow differential assembly to be installed at zero preload, the equivalent of a ``slip-fit'' in case, during backlash adjustment. Final preload is not added until backlash has been adjusted.
Pinion Depth Adjustment
1. Install pinion bearing races in housing using a suitable driver.
2. Lubricate pinion bearings and install bearings in races.
3. Mount depth gauging jig in housing, noting the following:
a. Assemble gauge plate onto preload stud.
b. Hold pinion bearings in position, insert stud through rear bearing and pilot and front bearing and pilot, then install retaining nut and tighten nut until snug.
c. Rotate tool to ensure bearings are properly seated.
d. Hold preload stud and tighten nut until 20 inch lbs.of torque, which is required to rotate stud. To prevent damage to bearing, tighten nut in small increments, checking rotating torque after each adjustment.
e. Mount side bearing discs on arbor, using step for disc that corresponds to base of housing.
f. Mount arbor and plunger assembly in housing, ensuring side bearing discs are properly seated, install bearing caps and tighten cap bolts to prevent bearing discs from moving.
4. Mount dial indicator on arbor stud with indicator contact button bearing against top of arbor plunger.
5. Preload indicator 3/4 revolution and secure to arbor mounting stud in this position.
6. Place arbor plunger on gauge plate, rotating plate as needed so that plunger rests directly on button corresponding to ring gear size.
7. Slowly rock plunger rod back and forth across button while observing dial indicator.
8. At point on button where indicator registers greatest deflection, zero dial indicator. Perform steps 7 and 8 several times to ensure correct setting.
9. Once verified zero reading is obtained, swing plunger aside until it is clear of gauge plate button and record dial indicator reading. Indicator will now read required pinion depth shim thickness for a ``nominal'' pinion.
10. Inspect rear face of drive pinion to be installed for a pinion code number. This number indicates in thousandths of an inch necessary modification of pinion shim thickness obtained in step 9.
11. Select pinion depth adjusting shim as follows:
a. If pinion is stamped with a plus (+) number, add that number of thousandths to dimension obtained in step 9.
b. If pinion is stamped with a minus (-) number, subtract that many thousandths from dimension obtained in step 9.
c. If pinion is not stamped with plus or minus number, dimension obtained in step 9 is correct shim thickness.
12. Remove gauging tools and pinion bearings from housing, noting installation position of bearings.
Pinion Installation
1. Install selected shim onto pinion shaft, lubricate rear pinion bearing with specified axle lubricant, then press rear bearing onto pinion using suitable spacers.
2. Install new collapsible spacer onto pinion shaft, then insert pinion assembly into housing.
3. Lubricate front pinion bearing, install bearing into housing and tap bearing over pinion shaft with a drift while assistant holds pinion in place. Old pinion nut and a large washer can be used to seat front bearing on pinion, but care must be taken not to collapse spacer if this method is used.
4. Install new pinion seal in housing, coat seal lips with grease, then mount driveshaft yoke on pinion shaft, lightly tapping yoke until several pinion shaft threads protrude from yoke.
5. Coat rear of pinion washer with suitable sealer, then install washer and new pinion nut.
6. Hold driveshaft yoke with suitable tool, then alternately tighten pinion nut and rotate pinion until endplay is reduced to zero.
7. When endplay is reduced to zero, check pinion bearing preload using a torque wrench.
8. Continue tightening pinion nut in small increments until specified pinion bearing preload is obtained, rotating pinion and checking preload after each adjustment. Exceeding preload specification will compress collapsible spacer too far, requiring replacement of spacer. If preload specification is exceeded, spacer must be replaced and adjustment procedure must be repeated. Do not loosen pinion nut to reduce preload.
Final Assembly & Backlash Adjustment
1. Ensure pinion depth and bearing preload are properly adjusted.
2. Install differential case assembly and selected side bearing shims, refer to Differential Side Bearing Preload, Adjust.
3. Install bearing caps in proper position and torque cap bolts to 55-60 ft. lbs.
4. Rotate assembly to ensure bearings are properly seated.
5. Mount dial indicator on housing with plunger bearing against tooth on ring gear. Use small contact button on indicator plunger so that contact can be made at heel end of tooth and position dial indicator with plunger in line with gear rotation and perpendicular to gear tooth.
6. Hold pinion stationary and rock ring gear back and forth while reading backlash on indicator.
7. Check backlash at 3 evenly spaced positions around ring gear and record readings. If backlash varies by more than .002 inch at any position, check ring gear installation and run-out, and correct as needed.
8. If backlash is not within specifications, remove differential case assembly and bearing shims keeping shims in order.
9. Backlash is adjusted by increasing thickness of one shim while decreasing thickness of opposite side shim by the same amount in order to maintain proper side bearing preload. Select shims to adjust backlash as follows:
a. If backlash is excessive, increase thickness of shim on gear tooth side and decrease thickness of shim on opposite side by the same amount.
b. If backlash is less than specified, decrease thickness of shim on gear tooth side while increasing thickness of opposite shim by the same amount. Each .002 inch change in shim thickness alters backlash by .001 inch.
10. Reinstall differential assembly, shims and bearing caps, torque bearing cap bolts to 55-60 ft. lbs., then recheck backlash and adjust as needed.
11. If side bearing preload was set to zero during side bearing preload adjustment, proceed as follows:
a. Remove both bearing caps and shim packs, keeping shim packs in respective left or right positions.
b. Select left side differential preload shim from specifications chart and insert shim between left bearing race and spacer, then install left bearing cap with bolts hand tight.
c. Select right side differential preload shim from specifications chart and insert shim between right bearing race and spacer using a soft faced hammer.
d. Install right bearing cap and torque all cap bolts to 55-60 ft. lbs.
12. Ensure ring gear teeth are clean and free from oil, then coat both drive and coast side of each tooth with marking compound.
13. Apply braking force to ``load'' ring gear, then rotate driveshaft yoke with wrench so that ring gear rotates one full revolution in each direction. Test made without ``loading'' gears will not yield satisfactory pattern, and excessive rotating of gears is not recommended.
Fig. 30 Gear tooth contact pattern:
14. Compare gear tooth pattern with Fig. 30, and correct assembly adjustments as needed.
15. When proper gear tooth contact pattern has been obtained, clean marking compound from gears.
16. Install axles and driveshaft.
17. Install rear cover using RTV or new gasket, then fill rear axle with appropriate lubricant. On models equipped with limited slip differential, add additive No. 1050428 or equivalent to rear axle lubricant.