Four Wheel Drive; Ball Joint Adjustment - Chevrolet 10 1971 Series Chassis Service Manual

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G ene ra l D e s c r i p t i o n
M ain te nan ce and A d j u s t m e n t s ............................ ............................3-11
C om ponent P a r ts R e p la c e m e n t ......................... ............................3-12
........................... .................
F re e - W h ee ling H u b s
F ro n t A xle A s s e m b l y ........................................ ............................3-15
F ro n t A xle Shaft A s s e m b ly ............................... ............................3-15
Primary purpose of four wheel drive is to provide
additional tractive effort in off-the-road driving in order
to overcome such obstacles as sand, deep mud or snow,
hilly terrain with steep grades, etc.
With four wheels capable of driving, all the vehicle
and payload weight is utilized to give maximum tire
traction.
The power unit is driven through a three-speed or
four-speed transmission and consists of an adapter and
a two-speed transfer case with a steering and driving
front axle. A single control lever is used to shift the
transfer case from direct drive to low four wheel drive
at a ratio of 1.94 to 1, thus eight forward speeds and two
in reverse is provided.
Front wheel drive may be engaged or disengaged at any
time without clutching when the transfer case is in direct
drive; however, in returning to 2 wheel from 4 wheel the
accelerator may have to be varied as steady pressure is
applied on lever. This releases gear tooth pressure
during shifting.
A yoke and trunnion universal joint permits continuous
power flow to each front wheel, regardless of the turning
angle.
Provisions for Power Take-off have been incorporated
in the transfer case.
FRONT AXLE
The front axle is a hypoid gear axle unit equipped with
steering knuckles. Axle assembly number and production
date are stamped on left tube of assembly.
Conventional truck service brakes are provided on all
4-wheel drive units.

Ball Joint Adjustment

Front axle ball joint adjustment is generally necessary
only when there is excessive play in steering, irregular
wear on tires or persistent loosening of the tie rod.
1. Raise vehicle on hoist then place jack stands just
inside of front springs.
2. Disconnect connecting rod and tie rod to allow inde­
pendent movement of each steering knuckle.

FOUR WHEEL DRIVE

(SERIES K 1 0 AND K20)
Page
3-12
GENERAL DESCRIPTION
M AINTENANCE A N D ADJUSTMENTS
INDEX
Steering K n u c k l e ........................................... ..................................3-16
T ra n s fe r C a s e ................................................. ..................................3-16
A d ap te r A s s e m b l y ........................................ ..................................3-16
B a ll Jo in t A d ju s t m e n t .................................. ..................................3-17
Special T o o l s ................................................. ..................................3-19
STEERING KNUCKLE A N D UNIVERSAL JOINT
To permit the front wheels to be driven as well as
turned, the axle is equipped with steering knuckles and
the axle shafts are equipped with yoke and trunnion type
universal joints.
TRANSFER CASE
Refer to Section 7 for service procedures.
ADAPTER ASSEMBLY
Refer to Section 7 for service procedures.
FREE WHEELING HUBS
Free-wheeling hubs are available for the front wheels
of four wheel drive vehicles. The purpose of these hubs
is to reduce friction and wear by disengaging the front
axle shafts, differential and drive line from the front
wheels when the vehicle is operated under conditions
where front wheel drive is not needed.
The engagement and disengagement of free-wheeling
hubs is a manual operation which must be performed at
each front wheel. The transfer case control lever must
be in 2-wheel drive position when locking or unlocking
hubs. Both hubs must be in the fully locked or fully
unlocked position. They must not be in the free-wheeling
position when low all wheel drive is used as the additional
torque output in this position can subject the rear axle to
severe strain and rear axle failure may result.
3. At top of knuckle, apply torque wrench to one of the
steering arms attaching stud nuts, then check torque
necessary to turn the steering knuckle.
Maximum torque should be:
15 ft. lbs......................................................Axle 44-5B
NOTE: Knuckle should turn smoothly through
turning arc but have no vertical end play.
FRONT SUSPENSION 3-11
Page
10-30 CHEVROLET TRUCK SERVICE MANUAL