GMC chervolet camaro 1999 Service Manual page 63

0-60 Vibration Diagnosis and Correction
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 that 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 (Wheel
Removal) 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), 90 degrees
apart. Number the marks 1 through 4.
The following procedure uses a trial and error method
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 to the
stock weight.
General Information
The last method involves running the vehicle at a
speed which the vibration is felt.
1. Carefully hold a piece of chalk up to the very end
of the propeller shaft. Barely touch the chalk to
the shaft.
2. Shut the engine
OFF
in order to stop the propeller
shaft from rotating. Do not step on the brake
pedal. Do not put the transmission in PARK.
3. Inspect the chalk mart<.
Q-
1 2
0.0 1.0 2.0
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If you performed the above procedure correctly, the
chalk mark will indicate the heavy spot on the
shaft. The heavy spot will deflect downward and touch
the chalk. If the chalk mark circles the entire shaft,
touch the chalk more gently to the shaft. Ensure that
the chalk touches only the heavy spot. Once the
heavy spot is located, place the hose
clamp 180 degrees opposite to the chalk mark (1).
Perform the following steps:
1. Place the hose clamp at the light spot, or at any
of tne 4 points marked previously.
2. Test drive the vehicle at the speed at which the
vibration occurred. Record any changes in the
vibration.
3. Move the clamp to the other positions.
4. Test drive the vehicle each time you move the
clamp. Record any changes in vibration.
Remember which position gives the best balance.
• If the vibration did not change at all or if the
vibration becomes worse, then one clamp is either
too light or too heavy. Repeat the procedure
using the two clamps together (2).
• If the previous step did not correct the problem,
repeat the procedure using the two clamps
separated in order to reduce the spinning weight.