Driveshaft Balancing

Vibration or shudder which is noticeable either on fast acceleration, when coasting, or when using the engine for braking, may be caused by the rear axle housing being loose on the rear suspension, improper tire balance, improper driveline installation, or driveline balance.

If driveshaft components are replaced and shaft vibration is encountered after installation, disconnect the shaft and remove the slip yoke. Rotate the slip yoke 180°; then, reconnect the shaft to the slip yoke and reinstall in vehicle. If the vibration persists, disconnect the shaft at the rear axle companion flange. Rotate the companion flange 180° and reconnect the shaft to the flange.

If rotating the driveshaft 180° does not eliminate vibration, the driveshaft may be balanced, using the following procedure:

1. Raise the vehicle on a twin-post hoist so that both the front and rear axles are safely supported with all wheels free to rotate.

2. Remove the rear wheels and tires. Reinstall lug nuts to retain brake drums or rotors.

3. With the transmission in gear, increase the vehicle speed to the maximum vibration level. Note and record the speed of this vibration period as a base line speed.




4. Check the attachment of all U-joint bearing caps of the driveshaft to the transmission yoke for improper installation or damaged U-joint bearing cap locating lugs. All yokes with worn, shaved, or damaged locating lugs must be replaced.




5. With the transmission in gear, run the vehicle with the driveshaft rotating at a speedometer speed of 64-80 km (40-50 miles); have an assistant carefully bring a crayon, piece of chalk, or colored pencil up until it just barely contacts the rear end, center and front end of the driveshaft. The chalk marks will indicate the heavy side of the driveshaft. Use caution when checking the driveshaft near the balance weights to prevent injury to the hands.




6. Install two screw-type hose clamps on the driveshaft so that their heads are located 180° from the chalk mark, starting at the pinion yoke end of the driveshaft. Tighten the clamps.

7. Run the vehicle up to the baseline speed. If vibration is still evidenced, rotate the clamps approximately 45° away from each other and test for correction of vibration.

CAUTION: To prevent overheating, do not run the vehicle on the hoist for an extended period.

8. If necessary, continue to rotate the clamps apart in smaller increments until the vibration is eliminated or begins to be reduced.

9. If the vibration is not completely eliminated, repeat the foregoing procedure and balance the front end of the driveshaft, checking for elimination or reduction in the vibration level.

10. Reinstall wheels and tires.




11. Remove the vehicle from the hoist and road test.