Differential Case Assembly

Steps 1 through 4 apply to non-limited slip type units only.
1. Install side gears and thrust spacers, and pinion gears and washers into differential case. Install side gear thrust washers with oil grooves facing side gears.
2. Install pinion shaft. Do not install lock pin at this time.
3. Adjust differential gear backlash as follows:
a. Insert a wedge between side gear and pinion shaft to prevent side gear from turning.

Fig. 8 Measuring differential gear backlash:

b. Install suitable dial indicator to gear, Fig. 8, and measure gear backlash. Backlash must not measure more than .006 inch. on 1984 differentials or .008 inch on 1985-88 differentials.
c. If backlash exceeds specifications, install thicker side gear thrust spacers as needed, then recheck backlash.
4. Align pinion shaft lock pin hole with differential case lock pin hole and drive lock pin into place. Stake the lock pin in position in two places, using a suitable punch.

Fig. 9 Measuring depth of differential case. Limited slip type differential.:

5. On 1984-85 limited slip type units, adjust clearance between clutch plate and differential case when installing internal components as follows:
a. A = E - F + G, Fig. 9.

Fig. 10 Measuring thickness of preload spring. Limited slip type differential.:

b. Measure thickness of preload spring, Fig. 10. The total thickness of both springs will be considered as value L.

Fig. 11 Measuring width of pinion shaft and clutch plate assembly. Limited slip type differential.:

c. Assemble pinion shaft holder, pinion shafts, pressure rings and inner and outer clutch plates, then measure the total width, Fig. 11. This measurement will be considered value B.
d. Select shims and adjust so that difference between differential case depth A and the sum of values L, B and shim thickness C becomes the standard value.
6. On 1986-88 limited slip type units, adjust clearance between clutch plate and differential case when installing internal components as follows:

Fig. 12 Finding dimension A.:

a. Measure differential case depth (A), Fig. 12, (A=E - F + G).

Fig. 13 Measuring plate thickness.:

b. Measure spring disc and plate thickness, using a suitable tool, with both extended in the same direction and one placed over the other as shown, Fig. 13. Arrange them so that the difference between left and right is minimized, then measure thickness of friction plates and discs in the same manner. Right side (Lr) and left side (Ll).
c. Measure thickness of left and right clutch plate assemblies and find the difference of the two. Difference should not exceed .002 inch. Clutch plate assembly thickness is thickness of spring, disc spring plate, friction disc and friction plate.

Fig. 14 Finding dimension B.:

d. Assemble right and left friction plates, friction discs, pinion shafts and pressure rings, then measure total width (B), Fig. 14. Measure distance between clutch plates on a line with V-shaped groove in the pressure ring while pressing from both sides, ensuring groove is secured against pinion shaft. All parts should be dry.
e. Measure clearance between clutch plate and differential (S), then use the following formula: A - (B=Lr=Ll).
f. If the difference (S) between the depth (A) of differential case and the overall width (B) obtained previously, plus the spring plate and spring disc assembly thickness is not within .002-.008 inch, replace friction discs to adjust.

Fig. 15 Clutch assembly. Limited slip type differential.:

Fig. 16 Assembling differential clutch components.:

7. On all limited slip type units, apply clean gear oil to internal components, then assemble in reverse order of disassembly. Assemble clutch as shown, Figs. 15 and 16.
8. On 1986-88 limited slip type units, check drive pinion starting torque. Starting torque should be 36-58 ft. lbs. for new clutch plates or 25-58 ft. lbs. for used clutch plates.
9. On all units, thoroughly clean drive gear attaching bolts and remove tape from threaded holes of drive gear using an M10 1.25 tap. Clean the holes with compressed air.
10. Apply Loctite No. 270, or 271, to drive gear threaded holes, then install gear onto case with reference marks aligned. Torque attaching bolts alternately, in a diagonal sequence, to 58-65 ft. lbs.
11. Press side bearings into differential case using tool MB990802 or equivalent.
12. Adjust drive gear backlash as follows:
a. Install side bearing adjusting spacers, thinner than those removed, to the side gear bearings, then install differential case assembly into gear carrier. Select adjusting spacers of the same thickness for both the drive pinion side and the drive gear side.
b. Push differential case to one side and measure clearance between gear carrier and side bearing adjusting space using two feeler gauges.
c. Remove, and measure the thickness of, side bearing adjusting spacers from one side.
d. To determine proper thickness spacer to be used, add .002 inch to thickness measured in step c and one-half the clearance measured in step b.
e. Install one pair of the correct spacers each to the drive pinion side and drive gear side.
f. Install differential case assembly, with side bearing adjusting spacers, into gear carrier. Gently tap spacers with a brass drift to seat them on bearing outer race.
g. Install bearing cap with reference marks aligned. Torque cap bolts to 40-47 ft. lbs.

Fig. 17 Measuring drive gear backlash:

Fig. 18 Adjusting drive gear backlash:

h. With drive pinion locked in place, measure drive gear backlash, Fig. 17, at four different points on the drive gear. Backlash should measure .004-.006 inch on all 1984-85 differentials and 1986-88 differentials less intercooler or .005-.007 inch on 1986-88 differentials with intercooler. If not, replace spacers as necessary to bring within specifications, Fig. 18.

Fig. 19 Checking gear tooth contact:

Fig. 20 Gear tooth contact pattern chart:

i. Check drive gear and drive pinion for proper tooth contact by applying suitable marking compound to both surfaces of drive gear teeth. Insert a brass rod between carrier and case and rotate spline coupling by hand one revolution in each direction, Fig. 19, while applying a load of approximately 2 ft. lbs. to the drive pinion. Adjust pinion height and backlash as needed until tooth contact pattern resembles standard pattern, Fig. 20.

Fig. 21 Measuring drive gear runout.:

13. Measure drive gear runout using a suitable dial indicator, Fig. 21. If runout exceeds .002 inch, change position of drive gear in differential case and recheck.