GMC 1990 Light Truck Repair Manual page 317

SUBJECT
Description
Disassembly of Axle
Inspection
Disassembly
Cleaning and Inspection
Cleaning
Inspection
Assembly of Axle
Differential Case Assembly
Pinion Bearing Cup Installation
Pinion Depth Adjustment
Pinion Installation
Differential Assembly Installation
Adjusting Backlash
Gear Tooth Contact Pattern Check
Final Assembly
Drive Axle Assembly
Outer Deflecting Ring
Outer Joint Seal
Outer Joint Assembly
Inner TH-Pot Seal
Specifications
Special Tools
DESCRIPTION
The front axle on the L-Van model utilizes a full-time
four-wheel drive system, with no disengagement fea­
ture.
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 drive
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.
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
thread adjusters.
The differential is used to allow the wheels to turn at
different rates of speed while the front axle continues
SECTION 4C5
L-VAN FRONT AXLE
CONTENTS
L-VAN FRONT AXLE 4C5-1
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.
DISASSEMBLY OF AXLE
INSPECTION
Perform the following checks before disassembling
the axle.
1. Remove the fill plug from the axle and drain the
axle lubricant into a suitable container.
2. Check the ring gear backlash. Refer to " Backlash
Adjustment." 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.
3. Inspect the case and oil for metal chips. Deter­
mine where the metal chips come from, such as a
broken gear or bearing cage.
4. Determine the cause of the axle problem before
disassembly if possible.
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