Driveline Angles

Driveline angularity is the angular relationship between the engine crankshaft, the driveshaft, and the rear axle pinion. Factors determining driveline angularity include ride height, rear spring, and engine mounts.





Calculate the driveline operating angles as follows.








1. Preliminary setup procedures.
1 Inspect the U-joints for proper operation.
2 Park the vehicle on a level surface such as a drive-on hoist, or back onto a front end alignment rack.
3 Verify the curb position ride height is within specifications with the vehicle unloaded, and all of the tires inflated to their normal operating pressures.
4 Rotate the transmission output yoke until vertical. This will simplify taking measurements.
2. Measure the slope of the components using the Anglemaster II Driveline Inclinometer. Record the measurements and the direction the component's slope,
3. Calculate the difference in the slope of the components to determine the U-joint operating angle.
^ When two connected components slope in the same direction, subtract the smaller number from the largest to find the U-joint operating angle. When two connected components slope in the opposite direction, add the measurements to find the U-joint operating angle.
^ The U-joint operating angle is the angle formed by two yokes connected by a cross and bearing kit. Ideally, the operating angles on each end of the driveshaft must:
- The equal or within one degree of each other.
- Have a three degree maximum operating angle.
- Have at least one-half of one degree continuous operating angle.

An incorrect driveline (pinion) angle can often be detected by the driving condition in which the vibration occurs.
^ A vibration during coast-down from 72 to 56 km/h (45 to 35 mph) is often caused by an excessive U-joint angle at the axle (pinion nose downward).
^ A vibration during acceleration, from 56 to 72 km/h (35 to 45 mph) may indicate an excessive U-joint angle at the axle (pinion nose upward).

If the tires and driveline angle are not the cause, perform the NVH tests to determine whether the concern is caused by a condition in the axle.

Universal Joint (U-Joint) Wear
Place the vehicle on a frame hoist and rotate the driveshaft by hand. Check for rough operation or seized U-joints. Replace the U-joint if it shows signs of seizure, excessive wear, or improper seating.

Drive Pinion Stem and Companion Flange
Check the companion flange runout when all other checks have failed to show the cause of vibration.

One cause of excessive companion flange runout is improper installation of the axle drive pinion seal. Check to see if the spring on the seal lip has been dislodged before replacing the ring gear and pinion.

Coupling Shaft/Center Bearing Alignment
Vehicle noise and vibration can be caused by a dislodged or failed driveshaft center bearing support rubber insulator, a contaminated driveshaft center bearing support or excessive compression of the rubber insulator.

Bearing Shimming
Drive-away shudder is the predominant symptom associated with driveline angles condition on vehicles with two-piece driveshafts. Drive-away shudder can usually be corrected by shimming down the driveshaft center bearing bracket.

If the drive-away shudder cannot be corrected by shimming down the driveshaft center bearing bracket, check the driveline angles.