Measuring Backlash

Install the J 34047, the J 25025-1, and the J 8001 as shown.
Place the indicator stem at the heel of a tooth.
Move the case through the case's free play while holding the pinion flange.
Record the dial indicator reading.

Fig 1: Measuring Backlash
Courtesy of GENERAL MOTORS CORP.

Specification

The backlash between the ring gear and the drive pinion should be between 0.08-0.25 mm (0.003-0.010 in) with a preferred specification of 0.13-0.18 mm (0.005-0.007 in).

Important: When adjusting the backlash, observe the following:
- Always turn the left ad the right differential adjuster nut sleeves in equal amounts.
- Turning the differential adjuster nut sleeves one notch will change the backlash about 0.08 mm (0.003 in).
- Once the proper backlash is obtained, turn the left differential-adjuster nut sleeve in one additional notch in order to preload the differential case side bearings.
If the backlash is too small, use the following procedure to adjust:
1. 5.1. Increase the backlash by turning the left differential adjuster nut sleeve in 1 notch and the right differential adjuster nut sleeve out 1 notch.
2. 5.2. Recheck the backlash and adjust as necessary.
If the backlash is too large, use the following procedure to adjust:
1. 6.1. Decrease the backlash by turning the right differential adjuster nut sleeve in 1 notch and the left differential adjuster nut sleeve out 1 notch.
2. 6.2. Recheck the backlash and adjust as necessary.
Once the proper backlash is obtained, turn the left differential adjuster nut sleeve in 1 additional notch using the J 42213 in order to preload the differential case side bearings.
Recheck the backlash and adjust as necessary.
Perform a gear tooth contact pattern check. Refer to GEAR TOOTH CONTACT PATTERN INSPECTION .