Pontiac tempest 1968 Service Manual page 141

4A-18
1968 P O N T I A C SERVICE M A N U A L
2. If replacing front pinion bearing, install new
outer race by using installer J 8611-01-P, J 7817-T
or F with driver handle J 8092 (Fig. 4A-33).
SETTING PINION D E P T H
The pinion bearing shim thickness (pinion depth)
must be determined:
a. whenever a new housing (carrier and tube
assembly) 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
face of 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 lo­
cated 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 nomi­
nal 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. All pinions produced
for service are "nominal" or "zero" pinions and
are unmarked.
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 (Pon­
tiac), one J 21777-2 " A " & " B " gauge plate, one
J 8619-12 pilot, one J 21777-8 washer (Pontiac only)
and one J 8619-13 bolt and nut. A J 8001 dial in­
dicator 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.
m
J 7817 TEMPEST AND
FIREBIRD
1. Make certain all gauge parts are clean. Check
particularly the discs, gauge pin ends, dial indicator
tip and gauge plate surface.
2. Lubricate front and rear pinion bearings and
position them in their respective races in carrier.
Bearings used with gauge must be those to be in­
stalled in car, in order to ensure accurate reading.
3. Pontiac - Thread J 21777-8 w a s h e r onto
J 8619-13 bolt to end of thread. Thread J 8619-13
bolt into J 21777-2 gauge plate, so plate rests against
J 21777-8 washer. Insert assembled gauge plate and
bolt through front and rear bearings with underside
of plate against J 21777-8 washer (Fig. 4A-34). Slip
J 8619-12 pilot over bolt end, with underside against
front bearing. Tighten nut finger tight while rotating
gauge plate to ensure proper seating. Check to be
sure gauge plate is centered over bearing (Fig.
4A-35), then torque nut to obtain a bearing preload
reading of 20 in. lbs. (obtained with gauge plate as­
sembly rotation). It may be necessary to hold stud
stationary with a wrench on plate at end of stud.
Tempest or Firebird - Thread nut on J 8619-13
bolt to end of thread. Thread J 8619-13 bolt into
J 21777-2 gauge plate so plate rests against nut.
Insert assembled gauge plate and bolt into carrier
through front and rear bearings with underside of
plate a g a i n s t rear bearing (Fig. 4A-34). Slip
J 8619-12 pilot over bolt end with underside against
front bearing. Tighten another nut fingertight while
rotating gauge plate to ensure proper seating. Check
to be sure gauge plate is centered over bearing (Fig.
4A-35), then torque nut to obtain a bearing preload
reading of 20 in. lbs. (obtained with gauge plate as­
sembly rotating). It may be necessary to hold stud
stationary with a wrench on flats at end of stud.
4. Install a stem on the J 8001 dial indicator and
mount loosely on cross shaft. Position stem of in­
dicator on head of gauge pin so that stem is slightly
depressed (causing a low indicator reading). Tighten
thumb screw on indicator and set at zero.
5. Make certain bearing support bores are free
of burrs and d i r t . Place d i s c s J 21777-3-P,
J 8619-10-T or F on cross shaft assembly. Position
assembly in the carrier with the discs resting on the
bearing support bores and gauge pin facing in toward
gauge plate. Rotate discs to insure firm seating.
6. Position gauge plate so that, as cross shaft is
rotated (pressing firmly), the arc of the spherical
end of gauge pin scribes across the " B " - P , " A " - T
or F surface of the gauge plate (Fig. 4A-36).
7. Record maximum reading of dial indicator
throughout arc. When indicator scale is less than
.100", be sure to note if indicator completes more
than one revolution.
F i g . 4 A - 3 3 Installing Front Pinion Bearing Outer Race
8. Subtract recorded reading from .100". This
figure will be used to select correct shim in step 10.