Pontiac tempest 1968 Service Manual page 144

S T A N D A R D D I F F E R E N T I A L 4 A-21
F i g . 4 A - 3 9 Checking Pinion Bearing Preload
7. While observing the preceding caution, carefully
set preload drag to 25 lb. in. on new bearings or 17
lb. in. on used bearings.
8. Rotate pinion several times to assure that
bearings have been seated. Check preload again.
If drag has been reduced by rotating pinion, re-set
preload to specification.
INSTALL D I F F E R E N T I A L CASE AND
ADJUST SIDE BEARING PRELOAD
Production shims are cast iron and vary in thick-
neww from .210" to .272", in increments of .002".
NOTE: Whenever a case assembly is removed
from the housing, measure the production shims
for thickness and discard them (Fig. 4A-40).
This figure will be used to determine the approxi­
mate shim pack needed in step 4 (below). Use stand-
are .170" service spacers and steel service shims
(available from .040" to .082", in increments of
.002") for all service repairs.
NOTE: Do not attempt to reinstall the production
shims as they may break when tapped into place.
If service shims were previously installed, they
can be reused, but (whether using new or old bear­
ings) adhere to the following procedure in all
cases:
F i g . 4 A - 4 0 Measuring Original Production Shim
To adjust differential side bearing preload, change
the thickness of the right and left shims equally,
thus leaving the original backlash undisturbed.
1. Before installation of case assembly, make sure
side bearing surfaces are clean and free of burrs.
Lubricate side bearings with gear lube. If reusing
original bearings, the original outer races must also
be used.
2. Place differential case, with bearing outer
races in position, in carrier.
3. Slip one .170" service spacer between each
bearing race and carrier housing, with flat edge
against housing (Fig. 4A-41).
NOTE: As a safety precaution, install the left
bearing cap loosely so that the case may be moved
while checking adjustments (one 7/16"-14 x 4 1/2"
bolt can be added as an extra safety precaution in
the lower right bearing cap hole). This will pre­
vent the carrier from dropping while making shim
adjustments.
4. Subtract .365" (total of two .170" service
spacers plus .025" gauging space) from total shim
pack removed on disassembly. Select two shims
totaling this amount and position both between right
bearing race and service spacer. Be sure left bear­
ing race and spacer are against left housing of car­
rier (Fig. 4A-42).
5. Insert a feeler gauge of less than .100" between
right shim and service spacer (Fig. 4A-43).
NOTE: It will be necessary to work the case in
and out and to the left in order to insert the gauge.
The gauge must be inserted in order to judge the
drag. Be sure to locate the gauge at the centerline
of the bearing.
F i g . 4A-41 Installing Service Spacer