Pontiac FIREBIRD 1972 Service Manual page 370

4C-2 1972 PONTIAC SERVICE MANUAL
DRIVE PINION
A
PlNlON R E A R BEARING
.
1
i
gN
COMPANION FLANGE
OIL S E A L
/
PlNlON FRONT BEARING
-
C O L L A P S I B L E S P A C E R
C A R R I E R
' ; C" L O C K
PlNlON D E P T H SHIM
'-j
PlNlON GEAIF,
BEARING C % P
SIDE G E A R
COVER
'
7 '
PINION S H A F T L O C K B O L T
Fig. 4C-1 "C" Differential Cross Section
frame in sidewise alignment with the differential assembly.
The final drive has a ring gear and pinion with the center-
line of the pinion below the centerline of the ring gear
(hypoid type).
The drive pinion is mounted in two tapered roller bearings
which are preloaded by the collapsible spacer during as-
sembly. The pinion is positioned by shims located between
the drive pinion shoulder and the rear bearing. The pinion
and front bearing are held in place by a large pinion nut
and washer. The differential case is supported in the car-
rier by two tapered roller side bearings which are pre-
loaded by inserting shims between the outer race and the
carrier. Ring gear to pinion backlash is changed by vary-
ing the shim thickness from one side of the case to the
other. The case houses two side gears in mesh with two
pinion gears. Both the side gears and the pinion gears are
backed by thrust washers. The pinion gear shaft is an-
chored in the case by a bolt and lock washer.
The differential carrier is a nodular iron casting with tubu-
lar axle housings pressed into sides to form a complete
assembly (salsbury type). A removable heavy steel cover
is bolted to the carrier to permit servicing of the differen-
tial without removing the entire assembly from the car.
An oil feed passage to the pinion bearings and an oil return
hole are provided in the carrier casting for lubricant to
circulate. A pinion oil seal is located in the front of the
carrier and bears against the pinion flange. The oil filler
plug is located on the right side of the carrier.
The outboard axle shaft bearings receive lubrication from
the carrier housing through slots in the shim seats. Lubri-
cant flows from the carrier housing, through the slots in
the shim seats to the axle tubes. It then flows down a
groove in the tubes to the axle shaft bearing.
OPERATION
As the pinion rotates, power is transferred to the differen-
tial case through the ring gear. Since the differential side
gears are in mesh with the pinion gears and the pinion