Spicer Single Drive Axles Service Manual: 34DS, 34RS, 38DS, 38RS, DS340, RS340, DS380, RS380, DS400, RS400, DS3 - Manual (Page 36)

Adjustments
33
Adjust Tooth Contact Patterns
If necessary, adjust the contact pattern by moving the ring gear and drive pinion. Ring gear position controls the backlash. This
adjustment moves the contact pattern along the face width of the gear tooth, Pinion position is determined by the size of the pinion
bearing cage shim pack. It controls contact on the tooth depth of the gear tooth. These adjustments are interrelated. As a result,
they must be considered together even though the pattern is altered by two distinct operations. When making adjustments, first
adjust the pinion, then the backlash. Continue this sequence until the pattern is satisfactory.
Adjust Pinion Position
If the gear pattern shows incorrect tooth depth contact, change drive pinion position by altering the shim pack. Used gears should
achieve proper contact with the same shims removed from the axle at disassembly.
If the pattern is too close to the top land of the gear tooth, remove pinion shims. If the pattern is too close to the root of the gear
tooth, add pinion shims. Check ring gear backlash after each shim change and adjust if necessary to maintain the 0.006” to 0.016”
specifications.
Adjust Backlash
If the gear pattern shows incorrect face width contact, change backlash.
With the pattern concentrated at the toe (too far down the tooth), add backlash by loosening the bearing adjuster on the teeth side
of ring gear several notches. Loosen the opposite adjuster one notch. Return to adjuster on teeth side of ring gear and tighten
adjuster until it contacts the bearing cup. Continue tightening the same adjuster 2 or 3 notches. Recheck backlash.
If the pattern is concentrated at the heel (too far up-the tooth), remove backlash by loosening the bearing adjuster on the teeth
side of ring gear several notches. Tighten the opposite adjuster one notch. Return to adjuster on teeth side of ring gear and tighten
adjuster until it contacts the bearing cup. Continue tightening the same adjuster 2 or 3 notches. Recheck backlash.
INCORRECT PATTERN
Move pinion toward
ring gear.
Pattern too close to tooth top land and off center.
INCORRECT PATTERN
Move pinion
away from
ring gear.
Pattern too close or off tooth root.
INCORRECT PATTERN
Move ring gear
away from pinion
to increase backlash.
Pattern too close to edge of tooth toe.
INCORRECT PATTERN
Move ring gear
toward pinion
to decrease
backlash.
Pattern too far along tooth toward tooth heel.