Chevrolet 1991 Light Duty Truck Repair Manual page 151

10 1/2-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.
SUBJECT
D escription ................................................................................................................................................................ 4B4- 1
C hecking the Axle Before D isassem bly ......................................................................................................... 4B4- 1
D isassem bly o f the Rear Axle .......................................................................................................................... 4B4- 2
C leaning ................................................................................................................................................................. 4B4- 2
Inspection .............................................................................................................................................................. 4B4- 2
Assem bly of the Rear A xle ................................................................................................................................4B4- 5
Gear Tooth Pattern Check ..................................................................................................................................4B4- 9
A djustm ents A ffecting Tooth Contact .................................................................................................................4B4- 9
S pecifications ........................................................................................................................................................... 4B4-11
Special Tools ............................................................................................................................................................. 4B4-11
DESCRIPTION
The corporate 10 1/2-inch ring gear rear axle uses a
conventional ring 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 axle shafts.
This axle is full-floating. The axle shaft is supported
at the wheel ends by the wheel hubs. The bolts that
attach the shaft to the hub, support the axle at the hub.
The splined end of the shaft is supported by the differ­
ential.
The pinion gear is supported in a pinion cage by
three bearings: a pinion front bearing, a pinion rear
bearing, and pilot bearing. The pinion cage is separate
from the axle housing. Selective shims are used
between the pinion cage and the axle housing to set
the pinion depth. The pinion bearing preload is set by
crushing a collapsible spacer between the front and
rear bearings in the pinion cage.
The ring gear is bolted onto the differential case with
left-hand thread bolts.
The differential case is supported in the carrier hous­
ing by two tapered roller bearings. The differential and
ring gear are located in relationship to the pinion by
using two different bearing adjusting nuts. These allow
the differential to be moved from side to side by adjust­
ing the nuts in or out. The differential side bearing
preload is accomplished by tightening the differential
bearing adjusting nuts after the ring gear backlash has
been set. Two bearing caps are used to hold the differ­
10 1/2-INCH RING GEAR 4B4-1
SECTION 4B4
CONTENTS
ential into the rear axle housing as well as to supply
half of the threads for the bearing adjusting nuts.
The differential is used to allow the wheels to turn at
different rates of speed while the rear axle continues to
transmit 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 gasket 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 alpha­
betic broadcast code on the right axle tube near the
carrier. The carrier cover does not have a drain plug.
BEFORE DISASSEMBLY
Inspect
Remove the axle cover from the rear axle and drain
the axle lubricant into a suitable container.
1. Ring gear backlash. Refer to " Backlash Adjust­
ment" 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. 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 dis­
assembly if possible.
CHECKING THE AXLE
PAGE