Differential Assembly: Service and Repair
DISASSEMBLYFig. 2 Exploded View Of Drive Axle Assembly. 4WD Models:
1. Place attachment tool No. 398217700 in a suitable vise, then attach drive axle assembly to tool.
2. Remove plug, then drain differential gear oil.
3. Loosen attaching bolts, then remove spindles, using a suitable tool.
4. Mark position of left and right side retainers to facilitate installation, then attach tool No. 398457700 to differential case and remove retainers, using a suitable puller, Fig. 2.
5. Remove differential carrier. Ensure teeth do not contact case. When replacing side bearing, pull bearing cup from side bearing retainer.
6. Remove bearing cone from differential carrier, using puller tool No. 399527700.
7. Remove drive gear by straightening lock plates and removing retaining bolts.
8. Drive out pinion shaft lockpin using a suitable punch. Lockpin is staked to the differential case, do not drive out before unstaking.
Fig. 3 Exploded View Of Limited Slip Differential Case Assembly. 4WD Models:
9. Remove pinion shaft, pinion gears, side gears and thrust washers. On models with limited slip differential, replacement differential case components, Fig. 3, are not available, therefore disassembly is not recommended.
10. Hold companion flange using tool No. 398427700, then remove drive pinion nut.
11. Remove companion flange using a suitable puller.
12. Using a suitable drift, press end of pinion shaft and remove with bearing inner race, spacer and washer.
13. Press rear bearing inner race from drive pinion by supporting inner race with tool No. 398517700.
14. Remove oil seal from differential carrier.
15. Remove pilot bearing with front bearing inner race using a suitable drift.
16. When replacing pinion bearings, tap front bearing outer race and rear bearing outer race using a brass drift.
ASSEMBLY
1. Reverse procedure to assemble, Fig. 2.
a. Apply gear oil when installing bearings and thrust washers.
b. Ensure left and righthand races of bearings are installed in correct positions.
2. Adjust pinion bearing preload as follows:
a. Adjust pinion bearing preload with a spacer and washer between front and rear bearings. The adjustment must be carried out without the oil seal.
b. Press front and rear bearing outer races into differential carrier using a suitable drift.
c. Insert dummy pinion shaft No. 398507702 with pinion height adjusting washer and rear bearing inner race into carrier.
d. Install preload adjusting spacer and washer, front bearing inner race, dummy collar No. 398507703 and companion flange.
Fig. 4 Measuring Pinion Bearing Preload:
Fig. 5 Pinion Bearing Preload Adjusting Spacer Identification Chart:
Fig. 6 Pinion Bearing Preload Adjusting Washer Identification Chart:
e. Rotate drive pinion by hand to seat bearings and tighten pinion nut while measuring preload, Fig. 4. Select the adjusting washer and spacer so that specified preload is obtained when nut is torqued to 123-145 ft. lbs., Figs. 5 and 6.
3. Adjust drive pinion height as follows:
a. Adjust pinion height with a washer installed between rear bearing inner race and back of pinion gear.
Fig. 7 Installation Position Of Tools For Adjusting Drive Pinion Height:
b. Install dummy shaft, collar and gauge, tool set No. 398501600, and apply specified preload on bearings, Fig. 7.
c. Measure clearance between end of gauge and end surface of dummy shaft by using a feeler gauge.
Fig. 8 Pinion Height Adjusting Washer Identification Chart:
d. Obtain thickness of pinion height adjusting washer, Fig. 8, to be installed from the following formula: T = To + N - (H X .01) - .20mm when T = thickness of pinion height adjusting washer in mm, To = thickness of washer temporarily inserted in mm, N = reading of thickness gauge in mm and H = figure marked on drive piston head.
e. Install selected pinion height washer on drive pinion and press rear bearing inner race into position using tool No. 398177700.
f. Insert drive pinion into gear carrier, installed previously, selected preload adjusting spacer, washer, oil seal, companion flange and tighten with pinion nut. Torque pinion nut to 123-145 ft. lbs.
4. Assemble differential case as follows:
a. Install side gears and pinion gears with thrust washers and pinion shaft into differential case. Apply gear oil on both sides of thrust washers and side gears before installing.
b. Measure clearance between differential case and back of side gear.
Fig. 9 Side Gear Thrust Washer Identification Chart:
c. Adjust clearance as specified by selecting the side gear thrust washer. Side gear back clearance should be .004-.008 inch, Fig. 9.
d. Check condition of rotation after applying oil to gear tooth surfaces and thrust surfaces.
e. After driving in pinion shaft lockpin, stake both sides of hole to prevent pin from falling out.
f. Install drive gear on differential case. Torque attaching bolts to 51-58 ft. lbs., then lock washer. Tighten diagonally while tapping bolt heads.
5. Measure width of side bearing as follows:
Fig. 10 Measuring Side Bearing Width:
Fig. 11 Installing Side Bearing:
a. Before installing side bearings, measure bearing width by using a weight block of about 5.5 lbs., Fig. 10. Standard bearing width is .787 inch.
b. Press side bearing inner race onto differential case using a suitable drift and tool No. 398497701 included in puller set No. 399527700, Fig. 11.
6. Adjust side gear preload as follows:
a. The gear backlash and side gear preload can be determined by side retainer shim thickness.
Fig. 12 Differential Markings Positions:
Fig. 13 Side Retainer Adjusting Shim Identification Chart:
b. When replacing differential carrier, differential case, side bearing and side retainer, Fig. 12, obtain left and right retainer shim thicknesses, Fig. 13, by the following formula: T1 (left) = (A + C + G - D - E + H) X .01 + .76mm; T2 (right) = (B + D + G - F - H) X .01 + .76mm. when T1 & T2 = thickness of left and right retainer adjusting shims in mm, A & B = figure mark on differential carrier, C & D = figure mark on differential case, E & F = difference of width of left and right side bearings from standard width 20mm expressed in a unit of 1/100mm, G = figure marked on side retainer and H = figure marked on drive gear. If figure is not marked, regard as zero.
c. Use several shims to obtain calculated thickness.
d. Reverse disassembly procedure to install differential case to differential carrier.
Fig. 14 Side Bearing Retainer Position:
e. Install selected shim and O-ring on side retainer, then install retainer on carrier with arrow on retainer facing as shown in Fig. 14. Torque to 7-9 ft. lbs.
f. Measure drive gear to drive pinion backlash. Backlash should be .004-.008 inch. If reading is not within limits, correct by decreasing shim thickness on one side and increasing shim thickness on the other side by the same amount. Total shim thickness must be the same to maintain proper preload.
g. At the same time measure rotating resistance of drive pinion. Compare with resistance when differential case was not installed, if the increase in resistance is not within .07-.43 ft. lbs., readjust side retainer shim.
Fig. 15 Measuring Backlash:
h. Recheck backlash between drive gear and pinion after readjusting shims, Fig. 15.
Fig. 16 Measuring Runout:
i. Check drive gear runout and pinion and drive gear rotation for smoothness, Fig. 16.
7. Check and adjust tooth contact of drive gear, proceed as follows:
a. Apply red lead to both sides of three of four drive gear teeth.
b. Check the contact pattern after rotating drive gear several times. Ensure red lead is completely removed after inspection.
8. Using a suitable drift install oil seal and rear cover. Apply chassis grease to seal lips before installation.
9. After installation in vehicle, fill differential as described under Checking and Changing Fluid. Torque differential assembly nut to 51-58 ft. lbs., propeller shaft flange yoke to companion flange to 13-18 ft. lbs. and spindle retaining bolt to 23.1-27 ft. lbs.