Test Description
The numbers below refer to the step numbers in the diagnostic table.
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First-order driveline related vibrations are usually caused by components that exhibit excessive runout or imbalance. Reproducing a vibration concern in the service stall can aid in pin-pointing the component which may be at fault. (A vibration concern may appear to be either less severe or more severe when duplicated in a service stall, than when duplicated on the road.)
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First-order driveline related vibrations that could not be duplicated during the non-torque sensitive service stall test, could be caused by internal axle components. This test is designed to duplicated first-order driveline related vibrations that are sensitive to torque/load. (A vibration concern may appear to be either less severe or more severe when duplicated in a service stall, than when duplicated on the road.)
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First-order driveline vibrations can be caused by excessive runout of a propeller shaft.
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First-order driveline vibrations can be caused by excessive runout of the pinion flange. If a propeller shaft exhibits excessive runout at a pinion flange end only, the runout may actually be caused by the pinion flange.
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Re-indexing a propeller shaft to a pinion flange can reduce the amount of total combined runout which the components produce, which may in-turn reduce a vibration.
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 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 |
Refer to Trim Height Inspection in Suspension General Diagnosis. 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 |
