GMC 1989 Light Duty Truck, Repair Manual, Page: 245 / 998

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-INCH RING GEAR 4C1 -5
CLEANING AND INSPECTION
CLEANING
• Do not steam clean drive parts having ground and
polished surfaces such as gears, bearings, and
shafts. These parts should be cleaned in a suitable
solvent. All parts should be disassembled before
cleaning.
• Parts should be thoroughly dried immediately after
cleaning. Use soft, clean, lintless rags. Parts may be
dried with compressed air. Do not allow the bearings
to spin while drying them with compressed air.
INSPECTION
It is very important to carefully and thoroughly inspect
all drive unit parts before assembly.
Through inspection of the drive parts for wear or stress
and subsequent replacement of worn parts will eliminate
costly drive component repair after reassembly.
AXLE HOUSING
Inspect
• Carrier bore for nicks or burrs that would prevent the
outer diam eter of the pinion seal from sealing.
Remove any burrs that are found.
• Bearing cup surfaces for nicks or burrs. Remove
any burrs that are found.
• Housing for cracks. Replace the housing if any
cracks are found.
• Housing for foreign material such as metal chips,
dirt, or rust. Refer to “ C leaning” in this section.
DIFFERENTIAL
Inspect
Pinion gear shaft for unusual wear.
Pinion gear and side gear teeth for wear, cracks,
scoring, and spalling.
Thrust w ashers for wear.
Fit of the differential side gears in the differential
case.
Fit of the side gears on the axle shafts.
Differential case for cracks and scorring.
Replace all worn parts.
PINION AND RING GEAR
Inspect
Pinion and ring gear teeth for cracking, chipping,
scorring, or excessive wear.
Pinion splines for wear.
Pinion flange splines for wear.
Fit of the pinion on the pinion flange.
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.
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
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.
B earing cups for wear, cracks, b rin e llin g and
scorring.
Bearings and cups are only replaced as sets.
If the front 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 minute scratches
and pits on the rollers and the bearing cups from the
initial preload. Do not replace a bearing for this
reason.
Bearing caps for cracks or chips.
SHIMS
In sp e ct
Shims for cracks and chips. Damaged shims should
be replaced with an equally sized service shim.