GMC 1989 Light Duty Truck, Repair Manual, Page: 242 / 998

4C1-2
8
1/2-INCH RING GEAR
which are pressed onto the differential case. Two bearing
caps are used to hold the differential into the front axle
housing.
The differential is used to allow the wheels to turn at
different rates of speed while the front axle continues to
transm it the driving force. This prevents tire scuffing when
going around corners and prevents premature wear on
internal axle parts.
The front axle is sealed with a pinion seal, a seal at
each axle shaft, and by a gasket between the front cover
and the axle housing.
All GM front axles are identified by the part number on
the right axle tube near the carrier. The carrier cover does
not have a drain plug.
DISASSEMBLY OF AXLE
INSPECTION
Perform the following checks before disassembling the
axle.
1. Remove the axle cover from the axle and drain the
axle lubricant into a suitable container.
2. Check the ring gear backlash. Refer to “ Backlash
A d ju s tm e n t.” This inform ation can be used to
determine the cause of the axle problem. It will also
help when setting up the shim packs for locating
and preloading the differential case.
3. Inspect the case for metal chips. Determine where
the metal chips come from, such as a broken gear
or bearing cage.
4. Determine the cause of the axle problem before
disassem bly if possible.
DISASSEMBLY
|+ + | R em ove or D isconnect (Figure 1)
Tools Required:
J 8107-4 Differential Side Bearing Remover
Plug
J 22888 Differential Side Bearing Remover
J 8614-01 Pinion Flange Remover
J 8612-B Rear Pinion Bearing Cone Remover
• Place the axle in a suitable support.
1. Differential cover bolts (14) and differential cover
(
12
).
• Drain the gear lubricant into a proper container.
2. Axle shafts (33). Refer to the proper Light Duty Truck
Service Manual.
3. Pinion shaft lock screw (15).
4. Pinion shaft (17).
5. Differential pinion (21) and side gears (22).
• Roll the pinion gears out of the case with the
pinion thrust washers (20).
• Remove the side gears and the side gear
thrust washers (19). Mark the gears and the
differential case as left and right.
6. Differential bearing cap bolts (18).
7. Differential bearing caps (10).
• Mark the caps and the housing as left and
right.
NOTICE: Be careful when prying the differential
c as e o u t o f the ax le h o u s in g so as n o t to
d a m a g e t h e c o v e r g a s k e t s u r f a c e . T h e
differential case m ust be s u p p o rte d wh en it is
b ein g r e m o v e d to p re v e n t the case from falling
a n d dam ag in g the case.
8. Differential carrier (24)
• Pry the case from the axle housing at the
differential “ w indow ” (figure 2).
9. Bearing outer races (8) and shims (9).
• Mark the races and the shim s as left and right,
and place them with the bearing caps.
10. Differential side bearings (8) using J 8107-4 and
J 22888 (figure 3).
• The jaws of J 22888 must pull from beneath
the bearing cone and not the cage.
11. Ring gear bolts (23).
• Ring gear bolts use left-hand threads.
NOTICE: Do n ot pry the ring g e a r from the case.
T h is w i l l d a m a g e t h e r i n g g e a r a n d t h e
differential case.
12. Ring gear (7) from the differential case.
• Drive th e ring g e a r off with a brass drift.
L?
Inspect
• Drive pinion bearing preload (figure 4).
• For looseness of pinion assem bly by moving it
back and forth. (This indicates excessive
bearing wear.)
13. Pinion fla n g e nut (35) and w ash er (36) using
J 8614-01 to hold the pinion flange (figure 5).
14. Pinion flange using J 8614-01 (figure 6).
15. Pinion (7) from the axle housing.
• Thread the pinion nut halfway onto the pinion.
• Replace the differential cover (12) with two
bolts (14) to keep the pinion from falling to the
floor.
• Drive the pinion out of the housing with a
hammer and a soft drift (figure 7).
16. Collapsible spacer (4) from the pinion.
17. Outer pinion seal (38) and bearing (39).
18. Inner bearing (5) and shim (6) from the pinion.
• P ress th e b e a rin g o ff th e p in io n u sin g
J
8612-B (figure 8).
• Remove the shim.
19. Bearing cups (5) and (39) from the axle housing
using a hammer and a punch.