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Home >> Chevrolet >> 2002 >> Astro Van Passenger, AWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 814 (Vibration Symptoms Diagnosis And Correction - 2WD) >> Diagnostic Information and Procedures >> Propeller Shaft Phasing Inspection

Propeller Shaft Phasing Inspection

WARNING: This page is about a different car, the 2003 GMC Safari and 2003 Chevrolet Astro. However, it is still accessible from the selected car via links, so may be relevant.

Tools Required 

J 23498-A Driveshaft Inclinometer

Inspect the propeller shaft for correct phasing. Correct phasing means that the front and the rear U-joint are directly in line or parallel with each other so that proper cancellation takes place.

  1. Raise and support the vehicle. Ensure that the drive axle is supported at ride height - vehicle body supported by suspension components - with the wheels free to rotate. Refer to Lifting and Jacking the Vehicle in General Information.
  2. Place the transmission in NEUTRAL.
  3. Clean any corrosion or foreign material from the U-joint bearing caps.
  4. Remove any of the U-joint bearing cap snap rings that may interfere with the correct placement of the J 23498-A.
    Fig 1: Installing Driveshaft Inclinometer (J 23498-A) To Lower U-Joint Bearing Cap Of Propeller Shaft (2WD)
    G02665387Courtesy of GENERAL MOTORS CORP.
  5. Inspect the propeller shaft for proper phasing.
    1. Rotate the propeller shaft to align the rear shaft flanges vertically.
    2. Install the J 23498-A to the lower U-joint bearing cap of the rear U-joint of the propeller shaft. The J 23498-A should be aligned perpendicular to the propeller shaft.
    3. Set the indicator line on the J 23498-A to 15, the horizontal reference.
    4. Rotate the propeller shaft slightly to center the bubble to the indicator. The U-joint is now vertical.
    5. Without disturbing the setting on the J 23498-A, remove the J 23498-A from the rear U-joint bearing cap.
    6. Install the J 23498-A to the lower U-joint bearing cap of the front U-joint of the propeller shaft.
    7. Observe the reading of the front U-joint with the J 23498-A still set to 15, the horizontal reference.
  6. If the difference between the front and rear U-joints of a welded-yoke propeller shaft is 3 degrees or less, the propeller shaft is properly phased.
  7. If the difference between the front and rear U-joints of a welded-yoke propeller shaft is greater than 3 degrees, the propeller shaft is either constructed improperly, or damaged from twisting and it requires replacement to restore proper cancellation of the U-joints.
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