Chevrolet 1988 Light Duty Truck Repair Manual page 307

check, the best contact between the ring gear and the
drive pinion for low noise level and long life can be
assured.
GEAR TOOTH TERMS
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 " co a st" 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 the center is the
" heel" end. The toe end of the tooth is sm aller than the
heel end (figure 33).
TEST
1. W ipe oil out of carrier and carefully clean each tooth
of the ring gear.
2. Apply gear marking com pound sparingly to all ring
gear teeth using a m edium s tiff brush. W hen
properly used, the area of pinion tooth contact will
be visible when hand load is applied.
3. Apply a load until a torque of 54-70 N m (40-50 ft.
lbs.) is required to turn the pinion.
A test made w ithout loading the gears will not give
a satisfactory pattern. Turn the com panion flange
with a wrench so that the ring gear rotates one full
revolution then reverse the rotation so that the ring
gear rotates one revolution in the opposite direction.
E x c e s s iv e tu r n in g
recom mended.
4. Observe the pattern on the ring gear teeth and
compare with figure 34.
ADJUSTMENTS AFFECTING TOOTH CONTACT
Two adjustm ents can be made which will affect the
tooth co nta ct pattern. These are b a cklash and the
position of the drive pinion (pinion depth) in the carrier.
The effects of bearing preloads are not easily seen on
hand loaded teeth pattern tests. These adjustm ents
should be within specifications before proceeding w iht the
backlash and the drive pinion adjustments.
It may be necessary to adjust both pinion depth and the
backlash to obtain the correct pattern.
o f th e rin g g e a r is n ot
K TRUCK FRONT AXLE 4C4-15
T he p o s itio n of th e d riv e p in io n is a d ju s te d by
increasing or decreasing the shim thickness between the
pinion head and the inner race of the rear bearing. The
shim is used in the d iffe re n tia l to c o m p ensate for
m anufacturing tolerances. Increasing the shim thickness
will move the pinion closer to the centerline of the ring
gear. Decreasing the shim thickness will move the pinion
farther away from the centerline of the ring gear.
Backlash is adjusted by means of the side bearing
adjusting sleeves which move the entire case and ring
gear assem bly closer to, or farther from the drive pinion.
(The adjusting sleeves are also used to set side bearing
preload). To increase backlash turn the left sleeve in and
turn the right sleeve out an identical amount. To decrease
backlash, turn the right sleeve in and turn the left sleeve
out an identical amount.
It is im portant that the contact pattern be centrally
located up and down on the face of the ring gear teeth.
CARRIER CASE ASSEMBLY
Install or C o n n e ct (F ig u res 1 th ro u g h 4)
Bend the lock (51) over the sleeves (32). (Right side
only on K35 models).
Bolt (64) and lock (63) (K35 models).
R em ove or D is co n n e c t (F ig u res 1 th ro u g h 4)
1. Bolts (28).
Ijjl
2. Right carrier case half.
Clean
C a rrie r case and axle tu b e se a lin g su rfa ce s.
Remove all grease and oil. Use carburetor cleaner
or equivalent.
♦ « -
Install o r C o n n ec t (F ig u res 1 th ro u g h 4, 19,
and 35).
Tools Required:
J 36600 O utput Shaft Seal Installer (K15-25)
J 22833 O utput-Shaft Seal Installer (K35).
J 33842 Pilot Bearing Installer
J 36616 Bushing Replacer Set
A pply a bead of sealer (GM part no. 1052942
[Loctite 518] or equivalent) to one carrier case half
sealing surface.
Right carrier case half (29).
Bolts (28).
T ig h ten
• Bolts (28) to 47 N m (35 ft. lbs.).
3. Left seal (3). Use J 36600 (K15-25 m odels) or
J 22833 (K35 models). Drive into place with a soft
faced hammer.
4. Shaft (59) with deflector (2). Drive in place with a
brass hammer.
5. Bearing (21) to the output shaft (23). Use J 33842
(figure 35).
6. Output shaft (23) to the carrier.
7. Vent plug (60). Use a small am ount of sealer (GM
part no. 1052942 [Loctite 518] or equivalent) on the
threads.
8. Bushings (48). Use J 36616 (figure 19).