J-23498­A Driveshaft Inclinometer

Equivalent regional tools:Special Tools and Equipment

The working angle of a U-joint is formed by the difference between the angles of any 2 shafts that intersect. Propeller shaft systems that have 1 U-joint have 1 working angle; systems with 2 U-joints have 2 working angles, and so on. In a typical 1-piece prop system with 2 U-joints, the working angles are front (1) and rear (2):

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

• No U-joint 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.
• No U-joint working angle should exceed 4 degrees.
• Prop systems containing only 1 U-joint: The U-joint working angle should be within the range specified in this procedure.
• Prop systems containing 2 or 3 U-joints: The 2 U-joint angles each formed with the prop shaft that contains 2 welded yokes are designed to cancel each other during operation. These 2 working, or cancelling U-joint angles should be equal to each other within the range specified in this procedure provide effective cancellation of the U-joints.
• Prop systems containing 3 U-joints: The U-joint angle formed by the prop shaft that contains only 1 welded yoke is an odd, or non-cancelled angle. This working angle should be within the range specified in this procedure.
• Always orientate the J-23498-A Driveshaft Inclinometer, or equivalent so that it faces the same side of the vehicle for each measurement taken.



• Be sure to accurately record the measurements taken on a diagram, similar to the one shown.

1. For vehicles with solid axles, ensure that the vehicle has a full tank of fuel or the equivalent amount of weight in the correct location to simulate a full tank. The weight of 3.8 L (1 gal) of gasoline is approximately 2.8 kg (6.2 lb).
2. Raise and support the vehicle. On vehicles with solid axles, ensure that the drive axle is supported at ride height—vehicle body supported by suspension components. Suspension travel will not affect driveline angles on vehicles with direct-mounted drive axles. Ensure the wheels are free to rotate. Lifting and Jacking the Vehicle
3. For vehicles with 2-piece prop shaft systems, inspect the lateral alignment of the propeller shafts before proceeding:
1. From underneath the propeller shafts, look down the length of the shafts from front to rear. Inspect the alignment of the shafts to each other.
2. From underneath the shafts, if the propeller shafts are not aligned to each other in a straight line, then the lateral alignment of the prop shafts needs to be adjusted before proceeding.

   The propeller shaft support bearing assembly can be relocated slightly to one side in order to improve the alignment of the shafts. Ensure that you do not create a ground-out condition against the exhaust or any other component.

4. Place the transmission in NEUTRAL.
5. Clean any corrosion or foreign material from the U-joint bearing caps.
6. Remove any of the U-joint bearing cap snap rings that may interfere with the correct placement of the J-23498-A Driveshaft Inclinometer, or equivalent .



7. For all prop systems perform the first measurement:
1. Rotate the prop shaft to align the rear-most yoke flanges vertically.
2. Install the J-23498-A Driveshaft Inclinometer, or equivalent to the lower U-joint bearing cap of the rear-most yoke. This yoke may be part of a prop shaft, torque tube input shaft, or a drive axle pinion shaft. Measure and record the angle of the shaft.
8. For prop systems with 2 or 3 U-joints, perform this additional measurement:

   Without rotating the prop, install the J-23498-A Driveshaft Inclinometer, or equivalent to the lower U-joint bearing cap of the forward-most, vertically-aligned yoke. This yoke may be part of a prop shaft, transmission output shaft, or a transfer case output shaft. Measure and record the angle of the shaft.

9. For all prop systems perform the second measurement:
1. Rotate the prop shaft 1/4 turn to vertically align the flanges of the forward yoke that mates to the rear-most yoke.
2. Install the J-23498-A Driveshaft Inclinometer, or equivalent to the lower U-joint bearing cap of the forward mating yoke. This yoke may be part of a prop shaft, transmission output shaft, or a transfer case output shaft. Measure and record the angle of the shaft.
10. For prop systems with 3 U-joints, perform this additional measurement:

    Without rotating the prop, install the J-23498-A Driveshaft Inclinometer, or equivalent to the lower U-joint bearing cap of the forward-most, vertically-aligned yoke. This yoke may be part of a transmission output shaft, or a transfer case output shaft. Measure and record the angle of the shaft.

11. Remove the J-23498-A Driveshaft Inclinometer, or equivalent .
12. Install any U-joint bearing cap snap rings that were removed prior to installing the J-23498-A Driveshaft Inclinometer, or equivalent .
13. Calculate the U-joint working angle at each intersection of two shafts.

    Subtract the smaller number from the larger 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.

14. For prop systems with 1 U-joint; compare the working angle to the following specification guideline:

Specification Guideline

Prop systems containing only 1 U-joint: The U-joint working angle should be between 1/2 and 3/4 degrees.

15. For prop systems with 2 or 3 U-joints; compare the difference between the working angles of the cancelling U-joints to the following specification guidelines:

Specification Guideline

Allowable range of difference between cancelling U-joint working angles: 0.25 to 1.0 degrees

16. For prop systems with 3 U-joints; compare the working angle of the odd, or non-cancelled U-joint to the following specification guideline:

Specification Guideline

Prop systems containing 3 U-joints: The odd, or non-cancelled U-joint working angle should be between 1/10 and 1/2 degrees.

17. Any working angle that is not within the specification guidelines requires adjustment.