Pinion Gear: Adjustments

Fig. 10 Pinion depth gauge tool installation. Corvette:

Adjustment
The standard setting for the drive pinion is 2.565 inches on 7.874 ring gear axles or 2.625 inches on 8.5 inch ring gear axles.
1. Install pinion bearing races in housing using suitable driver.
2. Lubricate pinion bearings and install bearings in races.
3. Mount depth gauging jig in housing, Fig. 10, 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 10 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 proper side bearing discs on arbor.
f. Mount arbor and plunger assembly in housing, ensuring side bearing discs are properly seated, install bearing caps and tighten cap bolts until a slight resistance is felt while rotating arbor.
4. Mount a 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.

Installation
1. Install correct pinion depth shim in axle housing bearing cup bore, then install inner bearing cup using a bearing installer.
2. Apply appropriate axle lubricant to inner and outer pinion bearings. Apply oil to pinion seal, then install with seal installer.
3. Assemble new pinion preload shim stack with thickness being the same as was removed, then place preload stack on pinion and install pinion, oil slinger and end yoke in axle housing. Use a wooden hammer to tap end yoke onto pinion splines.
4. Install pinion nut and washer. While holding end yoke, torque pinion nut to 200 ft. lbs.
5. Using an inch lbs. torque wrench, check rotating torque of pinion shaft. Pinion rotating torque should be 25 inch lbs on 7.875 axles or 30 inch lbs. on 8.5 axles with new bearings. To increase preload, remove shims. To decrease preload, add shims.