Chevrolet 1977 light duty truck Service Manual page 339

PROPELLER SHAFT AND UNIVERSAL JOINT DIAGNOSIS
Checking and Correcting
Propeller Shaft Unbalance
1. Place vehicle on a twin post hoist so that the
re a r wheels are free to rotate.
2. Remove both rear tire an d wheel assemblies and
brake drums.
Use care not to apply brakes with
C A U T IO N :
drums removed.
3. Visually inspect propshaft, U-Joints and attach­
C O M P L A IN T
Leak at front slip yo ke.
N O TE: An occasional drop o f
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.
ments for m ud undercoating o r other discrepancies.
Make necessary corrections prior to running.
4.
speed where disturbance is at its peak, observe the
intensity of the disturbance.
5.
com panion flange. Reinstall shaft by rotating it 180°
from its original position. D eterm ine which position o f
the com panion flange gives the best balance.
6.
vehicle for final check o f balance. If balance is still
unacceptable, replace drive shaft.
D IA G N O S T IC C H A R T
PO SSIBLE CAUSE
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.
With vehicle running in gear at the indicated
Stop engine and disconnect drive shaft from
Install rear drums and wheels, and road test
C O R R E C T IO N
a. Replace seal i f cut by burrs on yo ke.
Minor burrs can be sm oothed by careful
use o f crocus cloth or honing w ith a
fine stone. Replace y o k e i f 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.