GMC 1989 Light Duty Truck Repair Manual page 224

4B6-6 12-INCH RING GEAR (ROCKWELL)
AXLE HOUSING
L 1
Inspect
• T h e c a rrie r bore for nicks or burrs th at w ould
prevent the outer d ia m e te r of the pinion seal from
sealing. R em ove any burrs that are found.
• T h e bearing cup bores for nicks or burrs. R em ove
any burrs that are found.
• T h e housing for cracks. R e p lac e the housing if any
cracks are found.
• T h e housing for foreign m aterial such as metal
chips, dirt, or rust. R e fer to " C le a n in g "
section.
DIFFERENTIAL
Inspect
• Pinion g ear shaft for unusual wear.
• Pinion g ear and side g ear teeth for wear, cracks,
scorring, and spalling.
• Thrust w ashers for wear.
• T h e fit of the differential side gears in the differential
case.
• T h e fit of the side g ears on the axle shafts.
• Differential case for cracks and scorring.
• R ep lace all worn parts.
PINION AND RING GEAR
L 1
Inspect
• Pinion and ring gear teeth for cracking, chipping,
scarring, or excessive wear.
• Pinion splines for wear.
• Pinion flange splines for wear.
• The fit of the pinion on the pinion flange.
• The sealing surface of the pinion flange for nicks,
burrs, or rough tool marks which would cause
damage to the seals' inside diameter and result in
an oil leak.
• Pinion cages for cracks, imperfections, corrosion,
pits and grooves.
• Replace all worn or broken parts.
• Ring and pinion gears are matched sets and are
both replaced any time a replacement of either is
necessary.
BEARINGS
L 1
Inspect
Bearings visually and by feel. The bearings should
feel smooth when oiled and rotated while applying
as much hand pressure as possible.
The large end of the bearing rollers for wear. This is
where tapered roller bearing wear is most evident.
Bearing cups for wear, cracks, b rin e llin g and
scorring.
Bearings and cups are only replaced as sets.
If the rear axle was operated for an extended period
of time with very loose bearings, the ring gear and
drive pinion will also require replacement.
Low mileage bearings may have minutes scratches
and pits on the rollers and the bearing cups from the
initial preload. Do not replace a bearing for this
reason.
in this
Figure 15— Measuring the Preload Torque
• Bearing caps for cracks or chips.
SHIMS
Inspect
Shims for cracks and chips. Damaged shims should
be replaced with an equally sized service shim.
ASSEMBLY OF THE REAR AXLE
PINION ASSEMBLY
+ + Install or C onnect (Figures 1 and 2)
Tools Required:
J 23723 Bearing Installer
J 3453 Flange Holding Bar
J 3154-04 Seal Installer
• Lubricate all parts with axle lubricant.
Pinion rear bearing (57) onto the pinion.
• Press the bearing onto the pinion using
J 23723.
Pinion pilot bearing (52) onto the pinion.
• Press the bearing onto the pinion.
Bearing lock ring (51).
• The ring must seat in the pinion ring land.
Pinion (37) into the cage (54).
Spacer over the pinion shaft.
Pinion front bearing (57).
• Press the bearing onto the pinion using
J 23723.
Rotate the cage several times to initially seat the
bearings.
Place the pinion assembly in a press, and apply a
load of 11 tons.
Wrap a soft wire around the cage and pull on the
line with a pound scale. M easure the rotating
torque, not the starting torque (figure 15).
The rotating torque should be 5 to 15 in. lbs. To
determine the inch pounds:
— Determine the diameter of the pinion cage in
inches.
F-04782