GM Service Manual Online
For 1990-2009 cars only

Tools Required

    • J 23498-A Driveshaft Inclinometer
    • J 23498-20 Driveshaft Inclinometer Adapter

Object Number: 182180  Size: SH

The working angle of a U-joint is formed by the difference between the angles of two shafts that intersect. One-piece propeller shaft systems have two working angles; front (1) and rear (2).

    • The front working angle (1) is formed by the intersection of the transmission output shaft and the propeller shaft.
    • The rear working angle (2) is formed by the intersection of the propeller shaft and the drive axle pinion.

When measuring and evaluating driveline working angles, observe the following:

    • The two working, or cancelling angles should be equal to each other within 1/2 degree to provide effective cancellation of the U-joints.
    • No working angle should exceed 4 degrees.
    • No working angle should be equal to zero. An angle of 0 degrees will cause premature U-joint wear due to a lack of rotation of the needle bearings in the U-joint.
    • Always orientate the J 23498-A so that it faces the same side of the vehicle for each measurement taken.

Object Number: 182332  Size: SH
    • Be sure to accurately record the measurements taken on a diagram, similar to the one shown.

Measurement Procedure

Important: If it is necessary to use the J 23498-20 adapter, first verify the accuracy of the J 23498-20 by inspecting the angle of an accessible joint using the J 23498-A , then inspecting the same joint angle using the J 23498-20 .

  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. Ensure that the vehicle has a full tank of fuel or the equivalent amount of weight in the rear to simulate a full tank. The weight of 3.8 L (1 gal) of gasoline is approximately 2.8 kg (6.2 lb).
  4. Clean any corrosion or foreign material from the U-joint bearing caps.
  5. Remove any of the U-joint bearing cap snap rings that may interfere with the correct placement of the J 23498-A .

  6. Object Number: 6500  Size: SH
  7. Measure the angle of the drive axle pinion.
  8. 6.1. Rotate the drive axle pinion to align the pinion yoke flanges vertically.
    6.2. Install the J 23498-A to the lower U-joint bearing cap of the drive axle pinion.
    6.3. Using the J 23498-A , measure and record the angle of the drive axle pinion.

    Object Number: 6502  Size: SH
  9. Measure the angle of the transmission output shaft yoke.
  10. 7.1. Do not rotate the propeller shaft. With the propeller shaft in the same position, the transmission output shaft yoke flange will be aligned vertically.
    7.2. Install the J 23498-A to the lower U-joint bearing cap of the transmission output shaft yoke.
    7.3. Using the J 23498-A , measure and record the angle of the transmission output shaft yoke.
  11. Rotate the propeller shaft 1/4 turn.
  12. Measure the angle of the propeller shaft.
  13. 9.1. Do not rotate the propeller shaft. With the propeller shaft in this position, the U-joints of the propeller shaft will be aligned vertically.
    9.2. Install the J 23498-A to the lower U-joint bearing cap of either of the U-joints on the propeller shaft.
    9.3. Using the J 23498-A , measure and record the angle of the propeller shaft.
  14. Remove the J 23498-A .
  15. Install any U-joint bearing cap snap rings that were removed prior to installing the J 23498-A .
  16. Calculate the working angles at each intersection of two shafts.
  17. Subtract the larger number from the smaller to obtain the working angle. For example: If the drive axle pinion has an angle of 16 degrees and the connecting propeller shaft has an angle of 13 degrees, then the working angle of that intersection is 3 degrees.

  18. Compare the working angles of cancelling U-joints, beginning at the rear-most position.
  19. If the working angles of two cancelling U-joints are not within 1/2 degree of each other, or if one or both of the angles exceed 4 degrees, then the angle requires adjustment.