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DIFFERENTIAL
48-1
SECTION 4 B
DIFFERENTIAL
CONTENTS OF THIS SECTION
General Description
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4B-1
Standard Differential
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4B- 1
Positive Traction Differential
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4B-1
Diagnosis
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4B-4
On Car Service
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4B-8
Unit Repair
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4B-9
Specifications
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4B-21
Special Tools
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4B-24
GENERAL DESCRIPTION
DESCRIPTION AND OPERATION
OF STANDARD AND POSITIVE
TRACTION DIFFERENTIAL
STANDARD DIFFERENTIAL
DESCRIPTION
The differential assembly is of the semi-floating type in
which the car weight is carried on the axle housing. The
differential assembly is designed for use with an open drive
line and coil or leaf springs. The differential has a hypoid type
ring gear and pinion with the centerline of the pinion gear
below the centerline of the ring gear.
All parts necessary to transmit power from the propeller
shaft to the rear wheels are enclosed in a salisbury type axle
housing (a carrier casting with tubes pressed and welded into
the carrier to form a complete carrier and tube assembly). A
removable steel cover bolted to the rear of the carrier permits
service of the differential without removing the entire
assembly from the car.
A universal joint connects the rear end of the propeller
shaft to a pinion flange, having a splined end which fits over
and drives the hypoid pinion gear. Two pre-loaded tapered
roller bearings support the hypoid pinion gear in the carrier.
The inner race of the rear bearing is a tight press fit on the
pinion stem. The inner race of the front bearing combines a
light press fit to a close slidingjit on the pinion flange end
of the pinion stem. The outer race of each bearing is pressed
against a shoulder recessed in the carrier. Tightening the
pinion nut compresses a collapsible spacer which bears
against the inner race of the front bearing and a shoulder on
the pinion stem. This spacer is used to enable accurate bearing
pre-load adjustment and maintain a pre-load on both front
and rear pinion bearings. Adjustment of the fore and aft
position of the pinion is obtained by placing shims between
the head of the drive pinion and the rear pinion bearing. The
differential case is of one-piece construction and is supported
in the carrier by two tapered roller side bearings. These are
pre-loaded by inserting shims between the bearings and the
Carrier. The differential case assembly is positioned for proper
ring gear to pinion backlash by varying the shim thickness
from side to side. The ring gear is bolted to the case. Two
side gears have splined bores for driving the axle shafts. They
are positioned to run in counterbored cavities in the case. The
two differential pinions have smooth bores and are held in
position by a solid pinion cross shaft, mounted and locked
in the differential case. All four gears are in mesh with each
other and because the pinion gears turn freely on their shaft,
they are as idler gears when the rear wheels are turning at
different speeds. The pinions and side gears are backed by
steel thrust washers.
POSITIVE TRACTION DIFFERENTIAL
DESCRIPTION
The positive traction differential differs from the
standard differential in that a different type of case assembly
is used. The positive traction case assembly provides
increased resistance to differential action and multiplies the
tractive force available at the wheel with the least traction.
This multiplied force is then available to the wheel with the
better traction.
Three types of positive traction differential case
assemblies are used: 1) Cone clutch type; 2) Plate clutch type
(waMe pattern plates and rounded ear lugs); and 3) Plate
clutch type (swirl pattern plates and square ear lugs). The
cone clutch type is only serviced as a complete case assembly.
The plate clutch type case assemblies are serviced
individually; the internal parts are not interchangeable
between types of differentials.
Rear
axle
assemblies
having
positive
traction
differentials may be identified by a rectangular stainless steel
tag on the five o'clock inspection cover bolt or by a red plastic
triangular tag on the filler plug. In addition, identification
may be made by reading the code letters from the forward
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