GMC Chevrolet Camaro 1998 Service Manual page 67

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General Information
Runout and Balance Testing with the EVA
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Ensure that the runout of the various driveline
components are within specifications. If the runouts
are within specifications, strobe balance the driveline.
The EVA is able to simplify the balancing process. ·
Use the following procedure: ·
1. Use the EVA in order to determine which end of
the propeller shaft has the most vibration. '
2, Mark the end of the propeller shaft (1) that has
the most vibration at four points (2), 90 d~grees
apart. Number the marks 1 through 4.
3. Mount the EVA sensor onto the bottom of the
following components:
• The differential housing
• The center bearing support (for two-part
propeller shafts)
• The transmission tailshaft assembly
4. Position the sensor as close to the propeller shaft
as possible. Ensure that the UP.side of the
sensor face$ up. Ensure that the sensor is
horizontal.
Notice: Do not use cruise control to maintain
vehicle speed.
5. Start the engine.
6; Turn off all engine accessories.
7. Place the transmission in gear.
8. Run the vehicle at the speed which causes the
most vibration in the propeller shaft.
9. Hook the timing light clip to the trigger wire.
10. Plug the vibration sensor into Input Aof the EVA.
Input B does not have strobe light capability.
11. Verify that the predominant frequency on the EVA
display matches the frequency of the original
vibration. Use the strobe light only if the rotation
speed of the propeller shaft is the predominant
frequency.
Vibration Diagnosis and Correction 0 .. 55
12. The EVA displays a series of questions in order to
select the correct filter. Press YES in order to
select the desired filter. Ensure that the frequency
is in the middle of the filter range. Use the full
range only as a last resort.
13. The EVA displays the test frequency, the
amplitude and the filter range. The driveline
is balanced when the amplitude is near two. In
some cases a slightly higher amplitude will provide
adequate balance.
14. Point the timing ,light at the propeller shaft. The
strobe effect will appear to freeze the propeller
shaft. Note which of the numbered marks is at the
bottom of the propeller shaft (the 6 o'clock
position). This position is the light spot.
15. Turn the engine off.
16. Install a weight directly on the light spot.
17. Start the engine.
18. Run the vehicle at peak vibration speed.
19. Strobe the propeller shaft again.
The propeller shaft is balanced if the strobe image is
erratic and the amplitude is near two.
The propeller shaft is not balanced if one of the
following conditions exist:
• The weight and the original light spot are at the
6 o'clock position - This condition means that
there is not enough weight on the propeller shaft.
In order to correct the balance, add a second
weight next to the first weight. Inspect the balance
again using the strobe light.
,I
1
0.0
1.0
2.0
If the weights are now between 90 and
180 degrees off (between the 9 and the
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3 o'clock positions) there is too much weight. In
order to correct the balance, split the two weights
equally on either side of the original light spot.
Splitting the weight will produce a total weight
between one and two weights.
Inspect the balance again using the strobe light.
Adjust the weights as necessary.