Chevrolet Light Duty Truck 1973, Service Manual

Page: 238 / 979

4 - 1 4 REAR S U S PEN SIO N A N D DRIVELINE
PROPELLER SHAFT A N D UNIVERSAL JO IN T D IA G N O S IS
Checking and Correcting
Propeller Shaft Unbalance—Vehicles with
8 -7 /8 " Ring Gear Differentials Only
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.
CAUTION:
Use care not to apply brakes with
drums removed.
3. With vehicle running in gear at the indicated speed
where disturbance is at its peak, observe the
intensity of the disturbance.
4. Stop engine and check for any mud or undercoat­
ing on the propeller shaft. If any is found, remove
it and again check the intensity of the vibration. If
vibration is still present, proceed to step 5.
5. Bring indicated speed up to the point where
disturbance was at its peak on the road test and
observe the intensity of the disturbance. Stop
engine and disconnect drive shaft from companion
flange. Reinstall shaft by rotating it 180° from its
original position. Determine which position of the
companion flange gives the best balance.
6
. Install rear drums and wheels, and road test vehicle
for final check of balance. If balance is still
unacceptable, replace drive shaft.
DIAGNOSTIC CHART
COMPLAINT
POSSIBLE CAUSE
CORRECTION
Leak at front slip yoke.
NOTE: An occasional drop of
lubricant leaking from splined
yoke is normal and requires no
attention.
a. Rough outside surface on splined
yoke.
b. Defective transmission rear oil
seal.
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.
Knock in drive line, clunking
noise when car is operated
under floating condition at
10
mph in high gear or
neutral.
a. Worn or damaged universal
joints.
b. Size gear hub counterbore in
differential worn oversize.
a. Disassemble universal joints, inspect
and replace worn or damaged parts.
b. Replace differential case and/or side
gears as required.
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.
a. Loose upper or lower control
arm bushing bolts.
b. Loose companion flange.
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.
Fig. 33A—Diagnosis Chart A
LIGHT DUTY TRUCK SERVICE MANUAL