Pinion Installation & Adjustment

Fig. 2 Typical rotating torque measurement:

Fig. 18 Typical front pinion bearing installation:

1. Record thickness of pinion depth adjusting shim removed during disassembly and record pinion depth modification code etched or stamped on pinion.
2. Install pinion depth shim in rear bearing race bore, then press front and rear pinion bearing races into housing using forcing screw and adapters.
3. Press rear bearing onto pinion shaft.
4. Lubricate pinion bearings, insert pinion bearing into housing and install front bearing, then seat front bearing on pinion using forcing screw and spacer, Fig. 18. Collapsible spacer and flange seal are not installed until pinion depth has been established.
5. Install pinion flange and nut and tighten nut to obtain specified bearing preload, rotating pinion and checking preload after each adjustment, Fig. 2.
6. Position depth gauge arbor over gauge block, install a dial indicator in gauge arbor with approximately .20 inch preload, then secure and zero dial indicator. Use the following tools or equivalents, to measure pinion depth:
a. 325: arbor, 331481; block (.276''), 331482.
b. Except 325: arbor, 331461; block (.374''), 331462.

Fig. 19 Measuring Pinion Depth:

7. Position gauge block on face of pinion and mount arbor and dial indicator assembly in side bearing cover bores in case with dial indicator plunger bearing against gauge block, Fig. 19.
8. Obtain measured pinion depth by adding dial indicator reading to gauge block height and record sum.
9. Factor recorded pinion depth modification number with nominal pinion depth to obtain desired pinion depth. Modification number is expressed as 1/100 of a millimeter. If modification number is stamped with plus (+) sign add that value to nominal depth; if number is stamped with minus (-) sign subtract that value. Nominal pinion depths are as follows:
a. 325: .355 inch.
b. Except 325: .453 inch.
10. Select shim to obtain desired pinion depth as follows:
a. If desired pinion depth is greater than measured pinion depth, subtract the difference between the values from the installed shim thickness, and select shim accordingly.
b. If desired pinion depth is less than measured pinion depth, add the difference between the two values to the installed shim thickness and select shim accordingly.
11. Remove pinion assembly, rear bearing race and shim.
12. Install selected pinion depth shim, then press rear bearing race into housing as outlined.
13. Lubricate pinion bearings, insert pinion assembly into housing, then install a collapsible spacer and front bearing on pinion shaft.
14. Seat front bearing on pinion shaft using forcing screw and spacer, Fig. 18, then install pinion flange seal.
15. Install pinion flange and nut along with pinion nut lock plate.
16. Hold pinion flange and torque pinion nut to 108 ft. lbs., rotating pinion to ensure bearings are properly seated, then check preload with a torque wrench, Fig. 2.
17. If pinion bearing preload is more than approximately 2 inch lbs. greater than value recorded during disassembly, or if specified pinion nut torque cannot be obtained without bottoming nut, replace collapsible spacer and repeat installation procedure.
18. When rotating torque value is properly established, secure pinion nut with lock plate.