Test Description
The numbers below refer to the step numbers in the diagnostic table.
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In most cases, the vibration can be reproduced in the stall, but it is either not as bad or a lot worse than experienced on the road. This is normal. The cause of first-order driveline vibrations is usually due to excessive runout or the imbalance of a component. The In-Stall test will help determine which component needs to be repaired or replaced.
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If the vehicle has a vibration that is equal to first-order driveline rotation, and it is not present when testing the vehicle in the stall, then it is possible that the vibration is being generated by internal rear axle components. This may also be true if the vibration was correctable in the stall but returned when the vehicle was driven on the road.
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First-order driveline vibrations can be caused by excessive runout of the propeller shaft.
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First-order driveline vibrations can be caused by excessive runout of the pinion flange. If a propeller shaft has excessive runout at the pinion flange only, and re-indexing the propeller shaft 180 degrees does not correct the condition, measure and correct the pinion flange runout before replacing the propeller shaft.
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Re-indexing the propeller shaft to the pinion flange aligns the runout of components which may reduce vibration. If vibration is not reduced or eliminated, return the components to their original positions.
Step | Action | Yes | No | ||||
|---|---|---|---|---|---|---|---|
1 | Has the Vibration Analysis - Road Testing table been completed? | Go to Step 2 | |||||
2 | Did you record frequency data from the J 38792-A during the Vibration Analysis - Road Testing procedure? | Go to Step 3 | Go to Step 5 | ||||
3 | Based on the Vibration Analysis - Road Testing table, is the concern first order driveline related? | Go to Step 6 | Go to Step 4 | ||||
4 | Based on the Vibration Analysis - Road Testing table, is the concern second order driveline related? | Go to Step 19 | Go to Step 5 | ||||
5 | Based on the Vibration Analysis - Road Testing table, is the concern a noise that is not felt? | ||||||
6 | Inspect the following components for wear or damage:
Are any of the components listed worn or damaged? | Go to Step 7 | Go to Step 8 | ||||
7 | Replace the damaged or missing components. Refer to one of the following procedures in Propeller Shaft:
Did you complete the replacement? | Go to Step 26 | -- | ||||
Attempt to duplicate the vibration in the stall. Refer to Vibration in Service-Stall Test (Non-Torque Sensitive) Were you able to duplicate the vibration? | Go to Step 10 | Go to Step 9 | |||||
Perform the Vibration in Service-Stall Test (Torque Sensitive) . Were you able to duplicate the vibration? | Go to Diagnostic Starting Point - Rear Drive Axle in Rear Drive Axle | ||||||
10 | Was the vibration most evident under the transmission mount? | Go to Step 11 | Go to Step 13 | ||||
Measure the runout at the rear of the front axle propeller shaft, if equipped, and measure the runout at the front of the rear axle propeller shaft. Refer to Propeller Shaft Runout Measurement . Does the runout measurement require that the propeller shaft(s) be replaced? | Go to Step 13 | Go to Step 12 | |||||
12 |
Is the vibration still present? | Go to Step 13 | Go to Step 26 | ||||
13 | Measure the runout of the complete propeller shaft(s). Refer to Propeller Shaft Runout Measurement . Does the runout measurement require that the propeller shaft(s) be replaced? | Go to Step 14 | Go to Step 15 | ||||
14 |
Was the vibration reduced or eliminated? | Go to Step 26 | Go to Step 17 | ||||
Determine the runout of the front axle pinion flange, if equipped and determine the runout of the rear axle pinion flange. Refer to the Pinion Flange Runout Measurement . Does the runout measurement require that the (front and/or rear) pinion flange be replaced? | Go to Step 16 | Go to Step 17 | |||||
16 | Replace the pinion flange. Refer to Front Differential Drive Pinion Flange/Yoke, Seal, and Dust Deflector Replacement , if equipped, in Front Drive Axle and/or Drive Pinion Flange/Yoke and/or Oil Seal Replacement in Rear Drive Axle. Did you complete the replacement? | Go to Step 26 | -- | ||||
Re-index the propeller shaft. Perform the following steps:
Was the vibration reduced or eliminated? | Go to Step 26 | Go to Step 18 | |||||
18 | Return the propeller shaft to it's original position and balance the propeller shaft. Refer to Driveline System Balance Adjustment . Were you able to balance the driveline system? | Go to Step 26 | |||||
19 | Inspect the following components for wear or damage:
Are any of the components listed worn or damaged? | Go to Step 20 | Go to Step 21 | ||||
20 | Replace the damaged or missing components. Refer to one of the following procedures in Propeller Shaft:
Did you complete the replacement? | Go to Step 26 | -- | ||||
21 |
Did you find and correct a condition? | Go to Step 26 | Go to Step 22 | ||||
22 | Measure the propeller shaft angles. Refer to Driveline Working Angles Measurement . Do the propeller shaft angles require adjustment? | Go to Step 23 | Go to Step 24 | ||||
23 | Adjust the propeller shaft angles. Refer to Driveline Working Angles Adjustment . Did you complete the repair? | Go to Step 26 | -- | ||||
24 | Inspect the propeller shafts for proper phasing. Refer to Propeller Shaft Phasing Inspection . Does the propeller shaft phasing require correction? | Go to Step 25 | |||||
25 | Correct the propeller shaft phasing. Refer to Propeller Shaft Phasing Correction . Did you complete the repair? | Go to Step 26 | -- | ||||
26 |
Is the vibration still present? | Go to Step 3 | System OK |
