Chevrolet Positraction; Disassembly; Inspection; Reassembly - Chevrolet 1973 Overhaul Manual

Fig. 14D—In sta llin g S pring Pack
20. Check alignment of spring retainer with side gears.
Slight movement of the spring pack can be made if
necessary.
21. Install side bearings and ring gear to case using
procedure outlined for the conventional differential.
22. Place differential in carrier and adjust bearings and
backlash as outlined for the conventional
differential.
23. Check operation of unit as follows:
a. Raise rear of vehicle until rear wheels are off
the ground, and remove one wheel and tire
assembly.
b. Attach Adapter J-5748 to axle shaft flange and
install a 1/2-13 bolt into adapter, shown in
Figure 15D.
c. With wheel and tire assembly still on vehicle
held firmly to prevent turning, measure torque
required to rotate opposite axle shaft with a
0-150 lb. torque wrench attached to J-5748.
Torque required to rotate axle shaft should be
no less than 40 ft-lbs.
Fig. 15D—M easuring Positraction R otating Torque
REAR AXLE D IFFERENTIA L CARRIER
CHEVROLET P O S IT R A C T IO N -F IG U R E 16D
A Chevrolet produced Positraction differential unit is
used optionally in 8 1/2 inch ring gear axles. Individual
components of this positraction unit are not interchange­
able with other design units.

Disassembly

1. Remove ring gear and side bearings following the
procedures established for the conventional differ­
ential unit. Remove pinion shaft.
2. Using a wide, blunt instrument such as a drift or
block of wood, drive the preload spring from the
case.
3. Support an axle shaft in a vise, and slide the case
into the shaft; then turn the case to remove both
pinions and thrust washers.
NOTE: The pinion shaft may be partially
installed to aid in rotating the case.
4. Remove the case from the axle shaft and remove
both side gears, clutch packs and shims. Mark the
gears, clutch packs and shims for reinstallation in
same positions.

Inspection

Check the clutch plates and discs for wear and signs of
overheating. Check the condition of the preload spring.
Check the gear teeth for signs of wear. Replace parts as
needed. Clean all parts to be used for assembly.
NOTE: The force required to compress the
preload sprinp to 1-5/16 inches should be 300
lbs. ± 30 lbs.

Reassembly

1. Lubricate the clutch discs and plates with
positraction lubricant.
2. Alternately position clutch plates and discs on a
side gear, beginning and ending with a clutch plate.
3. Position the side gear, clutch pack and original
shim into the case.
4. Install both pinion gears and thrust washers into
the case, and install pinion shaft.
5. Place the case onto an axle shaft supported in a
vise.
6. Insert a screwdriver between the pinion shaft and
the face of the side gear. Force the screwdriver in
until the clutch pack is compressed.
7. Check the backlash between side gear and pinion
gears. If backlash does not fall into the range of
.005" to .008", adjust the shim dimension as
required. Increasing shim thickness will decrease
backlash; to increase backlash, decrease the
thickness of the shim.
4 -4 3
OVERHAUL MANUAL