Spicer Tandem Drive Axles Pro-40 Single Reduction and Single Reduction with Differential Lock - Manual (Page 51)

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Forward Assembly
Adjust Ring and Pinion Tooth Contact Pattern
Note: Rear axle gearing is shown in the following instructions.
Correct tooth contact patterns and adjustments are the
same for forward and rear axles.
1. Identify if new or used gearing.
2. Check tooth contact pattern (new or used gearing).
New Gearing - Correct Pattern
Paint six ring gear teeth 180° apart with marking compound
and roll the gear to obtain a contact pattern. The correct pat-
tern is slightly below center on the ring gear tooth with length-
wise contact up off the toe. The length of the pattern in an
unloaded condition is approximately one-half to two-thirds of
the ring gear tooth in most models and ratios.
The pattern could vary in length and should cover 1/2 tooth or
more (face width). The pattern 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 char-
acteristic of the pattern.
Adjust used gear sets to display the same contact pattern
observed before disassembly. A correct pattern 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 variable and is considered acceptable as long as it
does not run off the tooth at any point.
Adjust Contact Pattern
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 pin-
ion 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.
1 - Face width
2 - Tooth Depth
3 - Heel
4 - Top land
5 - Root
6 - Toe
1
2
3
4
5
6
1 - Pattern along the face width could be longer