GMC S Series 1994, Repair Manual

Page: 131 / 919

SECTION 4B2
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 m ust be used when installing fasteners that require it. If the above conditions
are not followed, parts or system damage could result.
CONTENTS
SUBJECT PAGE
General D escription......................................................................................................................................................4B2- 1
Checking the Axle Before D isassem bly............................................................................................................. 4B2- 2
Disassembly of the Rear A x le ...............................................................................................................................4B2- 2
C lean in g ....................................................................................................................................................................... 4B2- 4
In sp ectio n .................................................................................................................................................................... 4B2- 4
Axle H o u sin g .......................................................................................................................................................... 4B2- 4
D ifferential................................................................................................................................................................4B2- 4
Pinion and Ring G ear...........................................................................................................................................4B2- 5
B e arin g s................................................................................................................................................................... 4B2- 5
S h im s.........................................................................................................................................................................4B2- 6
Assem bly of the Rear A x le .................................................................................................................................... 4B2- 6
Pinion Depth Adjustm ent.................................................................................................................................... 4B2- 6
Pinion Installation...................................................................................................................................................... 4B2- 7
Differential Case A ssem b ly................................................................................................................................4B2- 8
Side Bearing Pre-Load A djustm ent................................................................................................................. 4B2- 9
Backlash Adjustm ent............................................................................................................................................ 4B2-10
Gear Tooth Pattern C heck...................................................................................................................................... 4B2-11
Adjustments Affecting Tooth Contact................................................................................................................. 4B2-11
Final A ssem bly.......................................................................................................................................................4B2-13
S p e c ific a tio n s .................................................................................................................................................................4B2-14
Fastener Tightening Specifications......................................................................................................................4B2-14
Spacer and Shim S pecifications.......................................................................................................................... 4B2-14
Lubrication................................................................................................................................................................... 4B2-14
Special T o o ls .................................................................................................................................................................. 4B2-15
GENERAL DESCRIPTION
The corporate 8 1/2-inch ring gear axle uses a con­
ventional ring and pinion gear set to transmit the driving
force of the engine to the rear wheels. This gear set
transfers the 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
pressed into the housing. The shafts are retained in 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 roller bearing that is
pressed onto the pinion. The pinion bearing preload is
set by crushing a collapsible spacer between the bear­
ings 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
gears are located in relationship to the pinion by using
selective shims between the bearing and axle housing.
To move the ring gear, shims are removed from one
side and an equal amount added to the other side.
These shims are also used to preload the bearings
pressed into the differential case. Two bearing caps are
used to hold the differential in the axle housing.
The differential allows the wheels to turn at different
rates of speed while the axle continues to transmit the
driving force. This prevents tire scuffing during turns
and premature wear on internal axle parts.