Pre-Repair Investigation; Gear Tooth Nomenclature; Red Lead Test - Pontiac Grand Prix Service Manual

4A-12 1969 PONTIAC SERVICE MANUAL
Firebird
-
Disconnect rear spring from its shackles and
brackets and remove rear axle assembly from under
car.
9. Pontiac, Tempest and Grand Prix
-
Disconnect
upper control arms at axle housing.
10. Pontiac, Tempest and G r a d Prix
-
Disconnect
lower control arms at axle housing and remove rear
axle assembly from under car.
REPLACE
1. Rest car solidly on stands placed under frame side
members, with rear end of car high enough to permit
working underneath. Position axle assembly under car.
2. Pontiac, Tempest and Grand Prix
-
Connect lower
control arms to axle housing but do not torque.
Firebird
-
Connect leaf spring front eyes to their frame
brackets but do not torque.
3. Pontiac, Tempest and Grand Prix - Connect upper
control arms to axle housing but do not torque.
Firebird
-
Connect leaf spring rear eyes to their
shackles but do not torque.
4. Pontiac, Tempest and Grand Prix
-
Place rear
springs in position and jack axle housing upward until
shock absorbers will reach.
Firebird
-
Jack axle housing upward until shock
absorbers will reach.
5. Connect shock absorbers and tighten nuts to 65 lb.
ft.
6. Pontiac, Tempest and Grand Prix
-
Tighten upper
and lower control arm bolts to 110 lb. ft. or nuts to 80
lb. ft.
Firebird
-
Tighten bracket bolt nuts to 100 Ib. ft. and
shackle pin nuts to 50 lb. ft.
NOTE: Upper and lower control arms (Pontiac, Tem-
pest and Grand Prix), leaf springs (Firebird) and lower
shock absorber nuts must be torqued at curb position.
7. Install new axle housing to brake backing plate and
outer retainer gaskets, then place backing plates in
proper position and install axle shafts and wheels.
8. Connect rear universal joint to companion flange.
Install lock plates and nuts. Tighten nuts evenly to 12
lb. ft. torque. If lockwashers are used, tighten U-bolt
nuts to 14 lb. ft. torque.
CAUTION: U-bolt nuts must be torqued as specified, as
over-tightening will distort bearings and cause early
failure.
9. Connect rear brake hose to top of housing and bend
tabs over brake lines on housing.
10. Fill rear axle with specified gear lubricant.
11. Bleed rear brakes as outlined in Section 5.
PRE-REPAIR INVESTIGATION
A close examination of the differential prior to
disassembly will often reveal valuable information as
to the extent and type of repairs or adjustments
necessary. The information thus gained, coupled with
the report of malfunctioning, will provide a basis for
determining the degree of disassembly required. Since
the frequent causes of axle noise are improper
backlash or side bearing preload, or both, a few simple
adjustments may be all that is necessary to correct a
problem.
Therefore, before removing the differential from the
housing, the following checks should be made, with
the results recorded and analyzed:
A. Backlash
B. Pinion Bearing Preload
C. Red Lead Test
Use care at all times to keep dirt and other foreign
matter, such as grinder dust, soot or sand away from
differential to prevent possibility of slibsequent failure.
GEAR TOOTH NOMENCLATURE
The side of the ring gear tooth which curves outward,
or is convex, is referred to as the drive side. The
concave side is the coast side. The end of the tooth
nearest center of ring gear is referred to as the toe end.
The end of the tooth farthest away from center is the
heel end. Toe end of tooth is smaller than heel end. It
is very important that tooth contact be tested before
the differential camer assembly is disassembled and
before it is installed. Allowable
1
iations in the carrier
or pinion rear,bearing may cause the pinion to be too
far away from, or close to, the ring gear. Thus, the
tooth contact must be tested and corrected, if neces-
sary, or the gears may be noisy.
RED LEAD TEST
1. Mix a small amount of powdered red lead (available
from paint manufacturers and suppliers) with a drop
of engine oil and apply this mixture sparingly to all
ring gear teeth, using a medium stiff brush. When
properly used, the area of pinion tooth contact will be
visible when hand load is applied.
2. Tighten bearing cap bolts to 70 lb. ft. torque,
tapping heads of bolt intermittently while tightening,
to ensure proper seating of caps and sufficient
tightness.
3. Insert crank (Fig. 4A-15) in companion flange and,
pinion head and inner race of rear bearing. The shim
pack is used in the differential to compensate for
manufacturing tolerances. Increasing shim pack thick-