8 1/2-Inch Ring Gear - Chevrolet 1991 Light Duty Truck Repair Manual

8 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
Description ................................................................................................................................................................ 4B2- 1
Checking the Axle Before Disassembly ......................................................................................................... 4B2- 1
Disassembly of the Rear Axle .......................................................................................................................... 4B2- 2
Cleaning ................................................................................................................................................................. 4B2- 2
Inspection .............................................................................................................................................................. 4B2- 2
Assembly of the Rear Axle ............................................................................................................................... 4B2- 5
Gear Tooth Pattern Check ..................................................................................................................................4B2-11
Adjustments Affecting Tooth Contact ............................................................................................................ 4B2-12
Specifications ........................................................................................................................................................... 4B2-13
Special Tools ............................................................................................................................................................. 4B2-14
The corporate / -inch ring gear rear axle uses a
8 1 2
conventional ring gear 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 semi-floating. The axle shafts are sup­
ported at the wheel end of the shaft by a roller bearing
that is pressed into the housing. The shafts are
retained into the housing by retaining clips within the
differential. The pinion gear is supported by two
tapered roller bearings. The pinion depth is set by a
shim pack located 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 collaps­
ible spacer between the 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
selective shims between the bearing and the axle
housing. To move the ring gear, shims are deleted from
one side and an equal amount are added to the other
side. These shims are also used to preload the bear­
ings which are pressed onto the differential case. Two
bearing caps are used to hold the differential into the
rear axle housing.
8 1/2-INCH RING GEAR 4B2-1
SECTION 4B2
CONTENTS
DESCRIPTION
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 seal 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.
H Inspect
• Remove the axle cover from the rear axle and
drain the axle lubricant into a suitable container.
1. The ring gear backlash. Refer to "Backlash
Adjustment" in this section. This information can
be used to determine the cause of the axle prob­
lem. It will also help when setting up the shim
packs for locating and preloading the differential
case.
CHECKING THE AXLE
BEFORE DISASSEMBLY
PAGE