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48-2
1977 PONTIAC SERVICE MANUAL
side of the right axle tube, three inches outboard of the
carrier.
Axle Shaft and Wheel Bearings--Two types of axle shafts
and wheel bearings are used. One type rolls directly on the
axle shaft. With this type, the shaft is retained in the housing
by "C"-Locks in the differential side gears. This type may be
identified by reading the code letters from the forward side
of the right rear axle tube three inches outboard of the carrier.
The third letter "C", "G", "K", "0" (7 1/2" ring gear axle)
or "P" identifies this type. For example, the code letters
"WCG" would indicate a 3.08 ratio, standard differential,
and direct-on type roller bearing, "C"-Lock retained axle
shaft. The second type wheel bearing has its own inner race
and is retained on the axle shaft by a retainer ring. This type
may be identified by reading the code letters on the right rear
axle tube. The third letter "B" or "0" (8 1/2" ring gear axle)
identified this type. For example, the code letters "KWB"
would indicate a 3.08 ratio, standard differential, unit roller
wheel bearing retained in the axle housing by an outer
retainer plate bolted to the housing end flange and retained
on the shaft by a pressed on ring.
OPERATION
-
STANDARD
DIFFERENTIAL (FIG. 4B-1)
Power from the engine is transferred to the transmission
via clutch or a fluid coupling. The transmission then provides
the transfer of power to its output shaft, which is splined to
the propeller shaft by means of a universal joint connection.
Since the rear of the propeller shaft is connected to the
differential drive pinion through the pinion flange, the
transmission output shaft, propeller shaft, and differential
drive pinion all turn at the same speed.
Power from the drive pinion gear is transmitted to the
ring gear which is bolted to the differential case. When
driving in a straight line and there is equal resistance on each
rear wheel, the force through the drive pinion and ring gear
turns the axle shafts at the same rate of speed and there is
no movement between differential pinions and side gears.
When the vehicle turns a corner, the outer rear wheel
must turn faster than the inner wheel. The inner wheel,
turning slower with respect to the outer wheel, slows its
differential side gear (as the axle shaft is splined to the side
gear) and the differential pinion gears will roll around the
slowed differential side gear driving the other differential side
gear and wheel faster.
OPERATION
-
POSITIVE TRACTION
DIFFERENTIAL (FIG. 46-2)
The operation of the positive traction differential is the
same as the standard differential, except that there is
additional friction provided by the clutches (cone or plate
type). Under ordinary driving and cornering conditions, the
clutches slip, allowing the outside wheel to turn faster than
the inner. Under poor traction conditions, such as ice, snow,
or loose gravel under one driving wheel, the increased friction
provided by the clutches increases the driving torque
available to the wheel with the better traction. The clutches
(cone or plate type) are spring loaded to provide the increased
driving torque under extremely low tractive conditions.
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