Section 25 - Four-Wheel Drive Front Axle - Chapter 9
25-9-26
Ring Gear and Pinion Tooth Pattern Interpretation
When setting the pinion position, many of the service
manuals required a final pinion position check by
using gauges that verify the dimension from the
center line to the differential carrier (center line of the
ring gear) to the face of the pinion (button).
This surface (button) is not used on all new gears for
verifying the pinion position. The service tools will be
used to establish the proper amount of shims
required prior to installing the pinion gear. The final
pinion position will be verified by using the GEAR
CONTACT PATTERN METHOD, as described here.
Ring Gear and Pinion Tooth Contact Pattern
RH98K107
The toe of the gear tooth is the portion of the tooth
surface at the end towards the center. The heel of the
gear tooth is the portion of the tooth surface at the
outer end. The top land of a gear tooth is the surface
of the top of the tooth. Every gear has a
characteristic pattern. The illustrations show typical
patterns only, and explains how patterns shift as gear
location is changed. When making pinion position
changes, shims should be changed in the range of
0.05 mm (0.002 inch) to 0.10 mm (0.004 inch) until
correct pattern has been obtained.
When a change in backlash is required, backlash
should be changed approximately 1-1/2 times the
amount needed to bring the gears into specification.
For example, if the backlash needed to be changed
by 0.10 mm (0.004 inch), the adjusting rings should
be moved so that the backlash changes by 0.15 mm
(0.006 inch) as a starting point. The actual amount of
backlash change obtained will vary depending upon
the ratio and gear size once everything is tightened
to specification.
High backlash is corrected by moving the ring gear
closer to the pinion. Low backlash is corrected by
moving the ring gear away from the pinion.
1. Paint the ring gear teeth with a marking
compound to both the forward and reverse side.
RD02J026
2. Rotate the ring gear one complete revolution in
both directions.
Pattern Interpretation (Ring Gear)
RH98K108
1. Normal or desirable pattern. The forward pattern
should be centered on the tooth, but slightly
toward the toe. There should be some clearance
between the pattern and the top of the tooth.
2. Backlash correct. Thinner pinion bearing cup
position shim required.
3. Backlash correct. Thicker pinion bearing cup
position shim required.
4. Pinion position shim correct. Decrease backlash.
5. Pinion position shim correct. Increase backlash.
FORWARD
DIRECTION
PATTERN
REVERSE
DIRECTION
PATTERN
1
2
3
4
5
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