GMC chevrolet camaro 2000 Service Manual page 67

0-56 Vibration Diagnosis and Correction
Correcting Vibration at the Center Support
Bearing
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These guidelines apply to the two-piece propeller shaft
only, First-order driveline vibrations that occur mainly
at the center support bearing are usually the result
of excessive runout at the stub (splined) shaft.
Unlike other first-order driveline vibrations, these
vibrations can appear at unusually low speeds
of 40 km/h (25 mph) and up.
Perform the following procedure in order to correct this
type of vibration:
1. Mark the position of the rear propeller shaft at
both ends for proper reassembly.
2. Remove the rear propeller shaft from the vehicle.
3. Measure the runout of the stub shaft splines (3)
approximately 12.7 mm (0.5 in) from the end.
4. Replace the shaft if the runout exceeds the
tolerances.
Stub shaft/spline runout 0.076 mm (0.003 in).
Correcting the stub shaft/spline runout will usually
eliminate the vibration. If some residual vibration is still
present, perform a road test on the vehicle. Determine
if an on-vehicle system balance of the driveline is
necessary.
General information
Driveline System Balance without the
Electronic Vibration Analyzer (EVA)
The following procedure is designed to fine-tune the
balance of the propeller shaft while it is mounted in the
vehicle. This procedure will also correct residual
imbalance of the remaining driveline components.
Prior to balancing the driveline system, verify tha1 the
propeller shaft and the pinion flange runout are
within specification.
Important: Do not overheat the engine when
performing this procedure.
1 . Raise the vehicle to curb height. Support the
vehicle on a hoist or on safety stands. Do not
allow the axle to hang. Refer to Lifting and Jacking
the Vehicle in General Information.
2. Remove the rear tire/wheel assemblies. Refer to
Tire and Wheel Removal and Installation in Tires
and Wheels.
3. Determine which end of the propeller shaft has
the most vibration in order to identify where to
begin installing the hose clamps.
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4. Mark the end of the propeller shaft (1) which has
the most vibration at four points (2), 9.0 degrees
apart. Number the marks 1 through 4.
The following procedure uses a trial and error me1hod
of determining where to· place the hose clamps on
the shaft. Use the following tips in order tO help locate
the clamps:
1. Because the imbalance may be related to
propeller shaft runout, begin installing the clamps
at the low point of the propeller shaft runout.
(
2. When the plant workers balance the propeller
shaft, they use weights in graduated increments:
2 g (1/16 oz), 4 g (1/8 oz), etc. If the stock
weight is too light or too heavy, place the hose (
clamp either directly in line with or opposite fo the
stock weight.