Drive Pinion

Fig. 5 Removing drive pinion bearing races.:

1. Press drive pinion front and rear bearing outer races into gear carrier, Fig. 5.
2. Adjust drive pinion height as follows:
a. Install tool MB990903 or equivalent and drive pinion front and rear bearing into the gear carrier. Apply a thin coat of suitable grease to face of washer on tool.
b. Tighten nut on tool and measure drive pinion preload, which should be 6.7-8.7 inch lbs. on 1984 models or 1.3-3.2 inch lbs. on 1985-88 models without oil seal installed. Loosen or tighten nut as necessary to bring preload within specifications.

Fig. 6 Measuring drive pinion height:

c. Position cylinder of tool MB990552 or equivalent in side bearing seat of gear carrier, Fig. 6.
d. Using a feeler gauge, measure clearance between the two tools and select drive pinion rear shim(s) corresponding to this measurement.
e. Install shim(s) to drive pinion, then press rear bearings onto pinion.
3. Adjust drive pinion reload as follows:
a. Install drive pinion front shim(s) between drive pinion spacer and front bearing inner race.
b. Torque spline coupling retaining nut to 116-159 ft. lbs. on all 1984-85 differentials and 1986-88 conventional differential less intercooler or 137-181 ft. lbs. on 1986-88 convention differential with intercooler and 1986-88 limited slip differential, then measure drive pinion preload, without oil seal, as described in step 2.
c. Adjust preload, as necessary, by replacing drive pinion front shim(s) or spacer.
4. Remove spline coupling and drive pinion, then drive seal into place using tool MB990727 or equivalent.
5. Install spline coupling and drive pinion assembly with reference marks aligned. Torque spline coupling retaining nut to 116-159 ft. lbs. on all 1984-85 differentials and 1986-88 conventional differential less intercooler or 137-181 ft. lbs. on 1986-88 convention differential with intercooler and 1986-88 limited slip differential. Apply a thin coat of suitable grease to spline coupling washer mating surface before installing drive pinion assembly.
6. Using suitable tools, measure drive pinion preload. Preload should measure 6.7-8.7 inch lbs. on 1984 differentials, 1.3-2.2 inch lbs. on 1985 differentials, 3.0-3.9 inch lbs. on 1986-88 differentials less intercooler or 3.5-4.3 inch lbs. on 1986-88 differentials with intercooler. If preload is not as specified, replace shim(s) or spacer as necessary.

Fig. 7 Measuring spline coupling runout.:

7. Measure spline coupling runout using suitable dial indicator, Fig. 7. Runout should measure .004 inch, or less. If not, disassemble differential carrier and change position of spline coupling and drive pinion, then recheck runout.