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(c) Low Tooth Contact
In Fig. C it will be observed that the tooth contact
is heavy on the drive gear flank or dedendum, that
Is, low tooth contact. This Is the opposite condition
from that shown in (b) and Is corrected by moving
the pinion out of mesh, that Is, to increase the pinion
cone setting distance by removing shims from be--
tween the pinion Inner bearing cup and housing,
and removing the same thickness of preload shims
from between the pinion shank and the outer
bearing cone. This correction has a tendency to
move the tooth bearing towards the heel on drive I
and the toe on coast. It may therefore, be neces--
sary after making this change to adjust the drive
gear as described in paragraphs (d) and (e).
(d) Toe Contact
Fig. D shows an example of the toe contact which occurs when the bearing is concentrated at the small end of the tooth. To rectify this condition, move the drive gear out of mesh, that Is, Increase the backlash by transferring shims from the drive gear side of the differential to the opposite side.
(e) Heel Contact
Fig. E shows an example of heel contact which is indicated by the concentration of the bearing at the large end of the tooth. To rectify this condition move the drive gear into mesh, that Is, reduce back-lash by adding shims to the drive gear side of the differential and removing an equal thickness of shims from the opposite side.
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It is most important to remember when making this adjustment to correct a heel bearing, that sufficient backlash for satisfactory operation must be maintained If there is insufficient backlash the gears will at least be noisy and have a greatly reduced life, while scoring of the tooth profile and breakage may result. Therefore always maintain a minimum backlash requirement of 004 in. (.10 mm.).
Backlash
When adjusting backlash always move the drive gear, as the adjustment of this member has a more direct influence on backlash, it is necessary to move the pinion a con-siderable amount to appreciably affect backlash, i.e. ‘0051n. (.13 mm.) movement on the pinion will generally only give .001 in. (.025 mm.) variation on backlash.
Gear and pinion movement
Moving the gear out of mesh moves the tooth contact towards the heel and raises it slightly towards the top of the tooth. Moving the pinion out of mesh raises the tooth contact on the face of the tooth and slightly towards the heel on drive, towards the toe on coast.
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