Chevrolet 1991 Light Duty Truck Repair Manual page 299

ALL WHEEL DRIVE FRONT AXLE
7 1/4-INCH RING GEAR
NOTICE: When fasteners are removed, always reinstall them at the same location from which they were
removed. If a fastener needs to be replaced, use the correct part number fastener for that application. If
the correct part number fastener is not available, a fastener of equal size and strength (or stronger) may be
used. Fasteners that are not reused, and those requiring thread locking compound will be called out. The
correct torque value must be used when installing fasteners that require it. If the above conditions are not
followed, parts or system damage could result.
SU BJEC T
Description .................................................................................................................................................4C5- 1
Disassembly of Axle....................................................................................................................................4C5- 2
Inspection ................................................................................................................................................4C5- 2
Disassem bly............................................................................................................................................ 4C5- 2
Cleaning and Inspection.............................................................................................................................4C5- 2
Cleaning ..................................................................................................................................................4C5- 2
Inspection ................................................................................................................................................ 4C5- 3
Assembly of Axle........................................................................................................................................ 4C5- 3
Differential Case Assembly..................................................................................................................... 4C5- 3
Pinion Bearing Cup Installation..............................................................................................................4C5- 7
Pinion Depth Adjustment........................................................................................................................ 4C5- 7
Pinion Installation.................................................................................................................................... 4C5- 8
Differential Assembly Installation..........................................................................................................4C5- 8
Adjusting Backlash.................................................................................................................................4C5-10
Gear Tooth Contact Pattern Check.......................................................................................................4C5-10
Final Assembly....................................................................................................................................... 4C5-13
Drive Axle Assembly..................................................................................................................................4C5-13
Outer Deflector R ing..............................................................................................................................4C5-13
Outer Joint Seal..................................................................................................................................... 4C5-15
Outer Joint Assembly.............................................................................................................................4C5-16
Inner Tri-Pot Seal................................................................................................................................... 4C5-17
Specifications ........................................................................................................................................... 4C5-20
Special Tools..............................................................................................................................................4C5-21
The front axle on the All Wheel Drive model uses a
full-time four-wheel drive system, with no disengage­
ment feature.
The axle uses a conventional ring gear and pinion
gear set to transmit the driving force of the engine to
the wheels. This gear set transfers this driving force at
a 90 degree angle from the propeller shaft to the axle
shafts.
The pinion gear is supported by two tapered roller
bearings. The pinion depth is set by a shim pack locat­
ed 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 collapsible spacer
between the pinion bearings in the axle housing.
ALL W HEEL DRIVE FRONT AXLE 4C5-1
SECTION 4C5
C O N T E N T S
D E S C R I P T I O N
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
threaded adjusters.
The differential is used to allow the wheels to turn at
different rates of speed while the front axle continues to
transmit the driving force. This prevents tire scuffing
when going around corners and prevents premature
wear on internal axle parts.
The axle identification code is stamped on the top of
the carrier case, along the edge of the machined face
of the left half.
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