GMC 1989 Light Duty Truck Repair Manual page 149

S U B J E C T
D escription....................................................................................................................................................................................4B 2- 1
Checking the Axle Before Disassembly........................................................................................................................... 4B 2- 1
Disassembly of the Rear A xle ............................................................................................................................................. 4B 2- 1
C le a n in g .................................................................................................................................................................................... 4B 2- 4
Inspection..................................................................................................................................................................................4B 2- 4
Assembly of the Rear A x le ..................................................................................................................................................4B 2- 5
Gear Tooth Pattern C h e c k ..................................................................................................................................................4B 2 -1 0
Adjustments Affecting Tooth C o n ta c t............................................................................................................................. 4B2-11
S p e c ific a tio n s ............................................................................................................................................................................. 4B 2-12
Special T o o ls ............................................................................................................................................................................... 4B 2-13
The corporate 81 / 2 -inch ring gear rear axle uses a con­
ventional ring gear and pinion gear set to transmit the
driving force of the engine to the rear wheels. This gear
set transfers this driving force at a 90 degree angle from
the propeller shaft to the drive shafts.
This axle is semi-floating. The axle shafts are supported
at the wheel end of the shaft by a roller bearing that is
pressed into the housing. The shafts are retained into the
housing by retaining clips within the differential. The pin­
ion gear is supported by two tapered roller bearings. The
pinion depth is set by a shim pack located between the
gear end of the pinion and the roller bearing that is
pressed onto the pinion. The pinion bearing preload is set
by crushing a collapsable spacer between the bearings in
the axle housing.
The ring gear is bolted onto the differential case with
left-hand thread bolts.
The differential case is supported in the axle housing
by two tapered roller bearings. The differential and ring
gear are located in relationship to the pinion by using se­
lective shims between the bearing and the axle housing.
To move the ring gear, shims are deleted from one side
and an equal amount are added to the other side. These
shims are also used to preload the bearings which are
pressed onto the differential case. Two bearing caps are
used to hold the differential into the rear axle housing.
The differential is used to allow the wheels to turn at
different rates of speed while the rear 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 rear axle is sealed with a pinion seal, a seal at
each axle shaft end, and by a gasket between the rear
cover and the axle housing.
All corporate rear axles are identified by the part num­
ber on the right axle tube near the carrier. The carrier
cover does not have a drain plug.
SECTION 4B2
8 V 2 -INCH RING GEAR
CONTENTS
DESCRIPTION
8 2
V -INCH RING GEAR 4B2-1
CHECKING THE AXLE
BEFORE DISASSEMBLY
Inspect
• Remove the axle cover from the rear axle and drain
the axle lubricant into a suitable container.
1. The ring g ea r b a ckla sh . R efer to " B acklash
A djustm ent" in this section. This information 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.
2 . The case for metal chips and shavings. Determine
where these chips and shavings come from, such as
a broken gear or bearing cage.
• Determine the cause of the axle problem before
disassembly if possible.
DISASSEMBLY OF THE
REAR AXLE
Rem ove or D isconnect (Figure 1)
Tools Required:
J 8107-4 Differential Side Bearing Remover
Plug
J 22888 Side Bearing Remover
J 8614-01 Pinion Flange Remover
J 8612-B Rear Pinion Bearing Cone Remover
• Place the rear axle in a suitable support.
1. The differential cover bolts (14) and the differential
12
cover ( ).
• D ra in th e g e a r lu b ric a n t in to a p ro p e r
container.
2. Axle shafts (33). Refer to the proper service manual.
3. Rear axle seal (28) and bearing (27). Refer to the
proper service manual.
P A G E