Spicer Single Drive Axles Service Manual: S170, S190, S590 - Manual (Page 42)

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Ring Gear
Adjust Tooth Contact Position
Adjust Ring and Pinion Tooth Contact Pattern
Note: Rear axle gearing is shown in the following instruc-
tions. 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
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 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 con-
tact 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 domi-
nant characteristic 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 pat-
tern are highly variable and is considered acceptable as
long as it does not run off the tooth at any point.
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