For 1990-2009 cars

This procedure is designed to fine-tune the balance of the propshaft while it is mounted in the vehicle. The propeller shaft and the pinion flange runouts should be within tolerances before attempting to balance the system.

### Strobe Balance Testing with the Electronic Vibration Analyzer (EVA)

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, using the following procedure:

1. Turn the ignition ON.
2. Place the transmission in NEUTRAL.
3. Remove the rear tire/wheel assemblies. Refer to Tire and Wheel Removal and Installation in Tires and Wheels.
4. Remove the brake drums. Refer to Brake Drum Replacement in Drum Brakes.

(1) | Propeller Shaft
(2) | Chalk Marks

5. Mark the end of the propeller shaft that has the most vibration at 4 points, 90 degrees apart. Number the marks 1-4.
6. Mount the EVA sensor on the bottom of the component nearest to the end of the propeller shaft that has the most vibration:

• | The pinion nose

• | The transmission tailshaft assembly

• | The center bearing support (for those multiple-piece propeller shafts which use a center support bearing)

7. Position the sensor as close to the propeller shaft as possible. Verify that the UP side of the sensor faces up and verify that the sensor is horizontal.
8. Start the engine.
9. Turn OFF all engine accessories.
10. Place the transmission in gear.
11. Run the vehicle at the speed which causes the most vibration in the propeller shaft.
12. Hook the timing light clip to the trigger wire.
13. Plug the vibration sensor into Input A of the EVA. Input B is not applicable for this test.
14. 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.
15. 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.
16. The display shows the test frequency, the amplitude and the filter range. The driveline is balanced when the amplitude is near 2. In some cases, a slightly higher amplitude will provide adequate balance.
17. Point the timing light at the propeller shaft. The strobe effect will appear to freeze the propeller shaft. Remember which of the numbered marks is at the bottom of the propeller shaft, or the 6 o'clock position. This position is the light spot.
18. Turn the engine OFF.
19. Install a weight directly on the light spot.
20. Start the engine.
21. Run the vehicle at peak vibration speed.
22. Strobe the propeller shaft again.

• | The propeller shaft is balanced if the strobe image is erratic and the amplitude is near 2.

• | 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.

(1) | Balance Location
(2) | Clamps Together

- | If the weights are now 90-180 degrees off (between the 9 o'clock and the 3 o'clock positions), too much weight exists. In order to correct the balance, split the 2 weights equally on either side of the original light spot in order to produce a total weight between 1-2 weights (between 0-120 degrees apart). Inspect the balance again using the strobe light. Adjust the weights as necessary.

- | The weight and original light spot are 90-180 degrees off (between the 9 o'clock and the 3 o'clock positions). This condition means that one weight is too much. In order to correct the balance, split the two weights equally on either side of the original light spot in order to produce a total weight less than one (120-180 degrees apart). Inspect the balance again using the strobe light. Adjust the weights as necessary.

- | The weight and the original light spot are within 180 degrees of the 6 o'clock position. Move the weight towards the 6 o'clock position. Inspect the balance again using the strobe light. Adjust the weight as necessary. Refer to the previous two conditions.

If the shaft will not balance using two weights, place a third weight on the light spot. Split the first two weights in order to produce a total weight between two and three weights.

If three weights fail to balance the driveline, replace the propeller shaft.

When the propeller shaft balances, road test the vehicle in order to verify that the vibration is eliminated.

### 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.

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. Remove the brake drums. Refer to Brake Drum Replacement in Drum Brakes.
4. Determine which end of the propeller shaft has the most vibration in order to identify where to begin installing the hose clamps.

(1) | Propeller Shaft
(2) | Chalk Marks

5. Mark the end of the propeller shaft (1) which has the most vibration at 4 points (2), 90 degrees apart. Number the marks 1-4.

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: 1/16 oz, 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.

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 mark.

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. Perform the following steps:

(1) | Balance Location
(2) | Clamps Together

1. Place the hose clamp at the light spot, or at any of the 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 1 clamp is either too light or too heavy. Repeat the procedure using the 2 clamps together.

• | If the previous step did not correct the problem, repeat the procedure using the 2 clamps separated in order to reduce the spinning weight.

Continue the trial and error procedure using different weights in different locations until you achieve the best balance. If more that 3 clamps aligned in the same position are required, replace the propeller shaft.

If you are able to reduce the vibration in the stall, but are unable to eliminate the vibration completely, perform a road test on the vehicle. A slight vibration noticeable in the stall may not be noticeable on the road.

### Propeller Shaft Balance Weights

When using clamps in order to balance a propeller shaft with the total weight method, the correction weight required will often be a fraction or a multiple of one hose clamp. Use the following phasing procedure with two hose clamps in order to accurately place any required amount 0-2 weights (0.0-2.0 total weights).

(1) | Balance Location
(2) | Clamps Together

1. Ensure that the clamps are located with even spaces on either side of the light spot, or 180 degrees opposite the heavy spot.

The table containing the weight amounts in terms of the total weight and the included angle (spread) between the clamps is in specifications.

2. If the vibration does not change at all or gets worse, then one clamp is too light or too heavy. Repeat the procedure using the two clamps together.
3. If the previous step did not correct the problem, repeat the procedure using the 2 clamps separated in order to reduce the spinning weight.
4. Continue the trial and error procedure using different weights in different locations until you achieve the best balance.
5. If more than three clamps aligned in the same position are required, replace the propeller shaft.
6. If you are able to reduce the vibration in the stall, but are unable to eliminate the vibration completely, road test the vehicle. A slight vibration noticeable in the stall may not be noticeable on the road.