Spicer Tandem Drive Axles Pro-40 Single Reduction and Single Reduction with Differential Lock - Manual (Page 78)

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Adjust Ring and Pinion Tooth Contact Pattern
1 - Face width
2 - Tooth depth
3 - Heel
4 - Top land
5 - Root
6 - Toe
3. Identify if new or used gearing.
4. Check tooth contact pattern (new or used gearing).
New Gearing - Correct Pattern
• Paint six ring gear teeth 180° apart and roll the gear
to obtain a contact pattern. The correct pattern is
slightly below center on the ring gear tooth with
lengthwise contact up off the toe. The length of the
pattern in an unloaded condition is approximately
one-half (1/2) to two-thirds (2/3) of the ring gear tooth
in most models and ratios.
• The pattern could vary in length and should cover
half (1/2) of the tooth or more (face width). The pat-
tern should be evenly centered between tooth top
land and root and should be up off the tooth toe.
Used Gearing - Correct Pattern
• Used gearing will not usually display the square,
even contact pattern found in new gear sets. The
gear will normally have a “pocket” at the heal end of
the gear tooth. The more use a gear has had, the
more the line becomes the dominant characteristic
of the pattern.
• Adjust used gear sets to display the same contact
pattern observed before disassembly. A correct pat-
tern is up off the toe and centers evenly along the
face width between the top land and root. Otherwise,
the length and shape of the pattern are highly vari-
able and is considered acceptable as long as it does
not run off the tooth at any point.
1 - Pattern along the face width could be longer
Adjust Ring Gear Position (Backlash)
If the ring gear pattern shows incorrect face width contact,
change backlash by adjusting the ring gear.
If the pattern is too close to the edge of the tooth toe, move the
ring gear away from the pinion to increase backlash.
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Wheel Differential
Wheel Differential