Setting Pinion Depth - Pontiac FIREBIRD 1972 Service Manual

4A-22 1972 PONTIAC SERVICE MANUAL
Fig. 4A-3 1 Installing Front Pinion Bearing Outer Race
holes in the carrier. Be sure bearing caps seat
squarely on carrier. Use miff file lightly to
remove nicks and burrs.
PINION BEARING OUTER RACES
REPLACE
1. If replacing rear pinion bearing, install new outer
race by using installer J 8608 (B Series), J 6 197 (A or
G Series) with driver handle J 8092 (Fig. 4A-30).
2. If replacing front pinion bearing, install new outer
race by using installer J 86 1 1-0 1 (B Series), J 78 17 (A
or G Series) with driver handle J 8092 (Fig. 4A-3 1).
SETTING PINION DEPTH
The pinion bearing shim thickness (pinion depth) must be
determined:
a. whenever a new housing (carrier and tube assem-
bly) is to be used, and/or
b. new bearings and races are installed, or
c. the pre-repair investigation indicates the drive
pinion bearing shim should be changed.
Ring and pinion gear sets are matched in a special test
machine. All production pinions are marked on the face
of the pinion gear in thousandths of an inch if they vary
from a "nominal" setting. When a pinion is marked
"+"
(plus), it means that the pinion is located too far away
from the centerline of the ring gear. Shims must be added
to move the pinion closer to the ring gear and position the
pinion at the nominal setting. When a pinion is marked
"-" (minus), it means the pinion shims must be removed
to move the pinion away from the ring gear and position
the pinion at the nominal setting.
Pinion depth is set with pinion depth setting gauge
J
21777
which consists of the following: one J 21777-1 cross shaft
assembly, two J 21777-3 discs (B Series) or J 8619-10 (A
and G Series), one J 21777-26 gauge plate and bar (B
Series), one J 21777-2 "AW&"B" gauge plate, (A or G
Series), one J 5647-37 (B Series) or J 8619-12 (A and G
Series) pilot, one J 2 1777-8 washer (B Series only) and one
J 8619-13 bolt and nut. A J 8001 dial indicator must also
be used with the cross shaft. The pinion depth setting
gauge provides in effect a "nominal" or "zero" pinion as
a gauging reference.
1. Make certain all gauge parts are clean. Check par-
ticularly the discs, gauge pin ends, dial indicator tip
and gauge plate surface.
2. Lubricate front and rear pinion bearings with gear
lubricant and position them in their respective races
in carrier. Bearings used with gauge must be those to
be installed in car, in order to ensure accurate read-
ing.
3. Assemble pinion setting gauge assembly, as shown in
Fig. 4A-32, into carrier assembly and tighten hex nut
while rotating gauge plate. Check that gauge plate is
centered over bearing (Fig. 4A-33 ,and 4A-34), then
torque nut to obtain a bearing preload reading of 20
lb. in. (obtained with gauge plate assembly in rota-
tion).
4. Make certain differential side bearing support bores
are clean and free of burrs.
5.
Position the dial indicator, J 8001, on the mounting
post of the gauge shaft with the contact button touch-
Fig. 4 A - 3 2 Pinion Gauge Tools