Chevrolet 1977 light duty truck Service Manual page 354

E Q U A L T R A C T IO N IN
S T R A IG H T A H E A D D R IV IN G
B A L A N C E D F O R C E S M A K E
D IF F E R E N T IA L S E E M L O C K E D
Fig. 4B-1--D ifferential Inactive
OUTSIDE WHEEL
HAS FARTHER,*
TO TRAVEL
BOTH WHEELS
TURN AT SAME
SPEED WHEN
TRAVELING
STRAIGHT
Fig. 4B-2-N eed for D iffe re n tia l Action
wheel slows to 90% o f vehicle speed, the outer wheel
speeds up to 110%. If the inner wheel slows to 75%, the
outer wheel would turn 125%. If one wheel stopped, the
other wheel would turn 200%.
Six distinct axles compromise the truck line-up.
These six, categorized by ring gear diameter, are a) 8-1/
2"
and b) 8 -7 /8 " Ring G ear, c) Chevrolet 10-1/2" Ring
G ear, d) D a n a 10-1/2" Ring G ear, e) D a n a 9 -3 /4 " Ring
G e a r and f)Chevrolet 12-1/4" Ring Gear.
8 - 1 / 2 " and 8 - 7 / 8 " Ring Gear Axle
The axle shown in figure 4B-4 is a semifloating,
fabricated constructed type consisting o f a cast carrier
with large bosses on each end into which two welded
steel tubes are fitted. The carrier contains an overhung
hypoid pinion an d ring gear. The differential is a two
pinion a rrangem ent.
The axle housing is m ade up of two steel welded
tubes pressed into the crossbore o f the cast carrier. Each
tube is puddle welded to the carrier. Welded-on brackets
provide attachm ent points for suspension componenets
such as shock absorbers and leaf springs. A welded
flange is provided for brake flange plate attachment.
An overhung hypoid drive pinion is supported by
two preloaded tapered roller bearings. The pinion shaft
is sealed by means o f a molded, spring loaded, rubber
seal. The seal is mounted on the pinion flange which is
splined and bolted to the hypoid pinion shaft.
The hypoid ring gear is bolted to a one-piece
differential case which is supported by two preloaded
tapered roller bearings.
Chevrolet 1 0 - 1 / 2 " Ring Gear Axle
The axle shown in figure 4B-5 is of the full floating
)]
n
type with hypoid ring gear and drive pinion. The full
V i i x
floating construction enables easy removal o f axle shafts
without removing truck load and without jacking up the
axle. The differential carrier is heavily ribbed to provide
rigid support for the differential assembly.
The straddle-mounted drive pinion is supported at
the front by two opposed tapered roller bearings. The
pinion straddle bearing is a roller bearing assembly
consisting o f an outer race and roller assembly. A
precision ground d iam eter on the pinion pilot functions
as an inner race.
Side
backlash are controlled by side bearing adjusting nuts
threaded into the carrier near the axle tubes. Pinion
depth is controlled by a shim located between the pinion
bearing retainer assembly and the differential carrier.
Dana 1 0 - 1 / 2 " Ring Gear Axle
The D ana axle shown in figure 4B-6 is a Salisbury-
type similar in design to the 8 -7 /8 " ring gear axle in
figure 4B-4. It does differ in several points, however. The
axle shafts are full floating; the carrier must be spread to
remove the differential; and the drive pinion incorpo­
rates two shim packs. The inner pack controls pinion
Fig. 4B-3--D ifferential Action on Turns
bearing preload and ring gear-to-pinion