Adjustments Affecting Tooth Contact

Two adjustments can be made that affect tooth contact pattern: backlash and pinion depth. The effects of bearing preloads are not readily apparent on hand loaded tooth contact pattern tests; however, these adjustments should be within specifications before proceeding with backlash and drive pinion adjustments.

Pinion depth is adjusted by increasing or decreasing the distance between the pinion head and the centerline of the ring gear. The shim is used in the axle to compensate for manufacturing tolerances. Decreasing the distance will move the pinion closer to the centerline of the ring gear. Increasing the distance will move the pinion farther away from the centerline of the ring gear.

Backlash is adjusted by means of the side bearing adjusting shims and for adjusting nuts. These move the case and ring gear closer to, or farther from, the drive pinion. The adjusting shims are also used to set side bearing preload.

If the thickness of the right shim is increased (along with an equal decrease in the left shim thickness), backlash will increase.

If the thickness of the left shim is increased (along with an equal decrease in the right shim thickness), backlash will decrease.