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48-6
1977 PONTIAC SERVICE MANUAL
I
TOE
I
HEEL
DRIVE SlDE
(CONVEX)
HEEL
COAST SlDE
(CONCAVE)
4847
I
TOE
HEEL
HEEL
DRIVE SIDE
(CONVEX)
COAST SlDE
(CONCAVE)
4849
Fig.
46-3
Gear Teeth Nomenclature
Fig.
46-4
Tooth Pattern
-
Pinion Too Far Away From Ring
only about halfway.
The important thing to note is that the contact pattern
is centrally located up and down on the face of the ring gear
teeth.
ADJUSTMENTS AFFECTING TOOTH
CONTACT
Two adjustments can be made which will affect tooth
contact pattern, backlash, and position of drive pinion in
carrier. The effects of bearing pre-loads ae not readily
apparent on (hand-loaded) tooth contact pattern tests;
however, these adjustments should be within specificatons
before
proceeding with
backlash
and
drive pinion
adjustments.
Backlash is adjusted by means of the side bearing
adjusting shims which moves the entire case and ring gear
assembly closer to, or farther from, the drive pinion. (The
adjusting shims are also used to set side bearing pre-load.)
The position of the drive pinion is adjusted by increasing or
decreasing the shim thickness between the pinion head and
inner race of rear bearing. The shim is used in the differential
to compensate for manufacturing tolerances. Increasing shim
thickness will move the pinion closer to centerline of the ring
gear. Decreasing shim thickness will move pinion farther
away from centerline of the ring gear.
EFFECTS OF PINION POSITION ON
TOOTH PATTERN
When the drive pinion is too far away from centerline
of the ring gear, the pattern will be a high heel contact on
the drive side and high toe contact on coast side. (Fig. 4B-4).
Moving the pinion closer to centerline of the ring gear by
increasing shim thickness will cause the high heel contact on
drive side to lower and move toward the toe; the high toe
contact on coast side will lower and move toward the heel
(Fig. 4B-5).
When the pinion is too close to the centerline of the ring
gear, the pattern will be a low toe contact on drive side, and
a low heel contact on coast (Fig. 4B-6). Moving the pinion
farther away from the ring gear by decreasing shim thickness
will cause low toe contact on drive side to raise and move
toward the heel; the low heel contact on coast side will raise
TOE
DRIVE SIDE
COAST SIDE
(CONVEX)
(CONCAVE)
4850
Fig.
46-5
Effect on Pattern as Shim Thickness is
Increased
and move toward the toe (Fig. 48-7).
Whenever the rear axle is overhauled to the point of
requiring a new ring gear and pinion set, the rear axle should
be filled ONLY with the lubricant included with the gear set.
Whenever the rear axle is overhauled to the point of requiring
only pinion and/or side bearings, it is recommended that
lubricant 105008 1, or equivalent, be used to refill for positive
traction units and for regular units.
ELIMINATION OF EXTERNAL NOISES
When a rear axle is suspected of being noisy, it is
advisable to make a thorough test to determine whether the
noise originates in the tires, road surface, front wheel
bearings, engine, transmission or rear axle assembly. Noise
which originates in other places cannot be corrected by
adjustment or replacement of parts in the rear axle assembly.
Road
Noise -
Some road surfaces, such as brick or
rough-surfaced concrete, cause noise which may be mistaken
for tire or rear axle noise. Driving on a different type of road,
such as smooth asphalt or dirt, will quickly show whether the
road surface is the cause of noise. Road noise usually is the
same on drive or coast.
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