GMC 1982 Light Duty Truck Service Manual page 405

PROPELLER SHAFT A N D UNIVERSAL JOINT DIAGNOSIS
Checking and Correcting
Propeller Shaft Unbalance
1. Place vehicle on a twin post hoist so that the rear wheels
are free to rotate.
2. Remove both rear tire and wheel assemblies and brake
drums.
Use care not to apply brakes with drums removed.
3. Visually inspect propshaft, U-Joints and attachments
for mud undercoating or other discrepancies. Make
necessary corrections prior to running.
C O M P L A IN T
Leak at front slip yoke.
NOTE: An occasional drop of
lubricant leaking from splined
yoke is normal and requires no
attention.
Knock in drive line, clunking
noise when car is operated
under floating condition at
10 mph in high gear or
neutral.
Ping, Snap or Click in drive
line.
NOTE: Usually occurs on
initial load application after
transmission has been put
into gear, either forward or
reverse.
4. With vehicle running in gear at the indicated speed
5. Stop engine and disconnect drive shaft from companion
6. Install rear drums and wheels, and road test vehicle for
D IA G N O S T IC C H A R T
P O S S IB L E C A U S E
a. Rough outside surface on splined
yoke.
b. Defective transmission rear oil
seal.
a. Worn or damaged universal
joints.
b. Side gear hub counterbore in
differential worn oversize.
a. Loose upper or lower control
arm bushing bolts.
b. Loose companion flange.
where disturbance is at its peak, observe the intensity of
the disturbance.
flange. Reinstall shaft by rotating it 180° from its
original position. D etermine whiph position of the
companion flange gives the best balance.
final check of balance. If balance is still unacceptable,
replace drive shaft.
C O R R E C T IO N
a. Replace seal if cut by burrs on yoke.
Minor burrs can be smoothed by careful
use of crocus cloth or honing with a
fine stone. Replace yoke if outside
surface is rough or burred badly.
b. Replace transmission rear oil seal.
c. Bring transmission oil up to proper
level after correction.
a. Disassemble universal joints, inspect
and replace worn or damaged parts.
b. Replace differential case and/or side
gears as required.
a. Tighten bolts to specified torque.
b. Remove companion flange, turn 180°
from its original position, apply white
lead to splines and reinstall. Tighten
pinion nut to specified torque.
PROPELLER SHAFT 4 A -3