Pontiac FIREBIRD 1972 Service Manual page 378

4C-10 1972 PONTIAC SERVICE MANUAL
Fig. 4C-2 1 Installing Service Spacer
Use a small button on indicator stem so that contact
can be made near heel end of tooth. Set dial indicator
so that stem is as nearly as possible in line with gear
rotation and perpendicular to tooth angle for accu-
rate backlash reading.
4. With pinion locked to carrier, check gear lash at 3 or
4 points around ring gear. Lash must not vary over
.00lV around ring gear. If variation is over .001"
check for burrs, uneven bolting conditions or dis-
torted case flange and make corrections as necessary.
Ring gear to pinion backlash should be in the range
of
.005"
to .008".
If original gear set is being reinstalled, original gear
lash should be maintained within
+
or
-
.001".
If gear backlash is not within specifications, correct
by increasing thickness of one differential shim and
decreasing thickness of other shim the same amount.
Shift .002" in shim thickness for each .00lW change
in backlash desired. If backlash is .002" too much,
decrease thickness of right shim .004" and increase
thickness of left shim .004".
If backlash is ,002" too little, increase thickness of
right shim .004" and decrease thickness of left shim
.004".
C,heck contact pattern with red lead as outlined in
Section 4A. The important thing to note is that the
contact pattern is centrally located up and down on
the face of the ring gear teeth towards the toe end.
After backlash and tooth pattern operations are com-
plete, remove shim packs taking care not to mix
them. Select new shim packs for each side .004"
thicker than those removed and install each shim
pack on its proper side. This additional thickness will
provide proper side bearing preload. It will be neces-
sary to tap the final shim into place with a soft ham-
mer.
AXLE SHAFT
INSTALL
Install axle shafts as outlined under "Axle Shaft Bearing
and Seal".
PROPELLER SHAFT TO PINION FLANGE
CONNECTION
CAUTION: See caution on Page I of this section
regarding the fasteners referred to below.
Fig. 4C-22 Checking Ring Gear t o Pinion Backlash
Connect propeller shaft to pinion flange with respect to
the alignment marks. Torque the four nuts to 12 lb. ft. (see
Section 4E).