Center Pinion Run-Out & Rephasing Drive Shaft Coupling

The paints spots on one arm of the final drive pinion yoke and on the drive shaft must be aligned with each other to ensure optimum balance.

If a condition of imbalance is suspected, the flexible joint and the final drive pinion yoke can be rephased by 120 degrees and the vehicle road tested to check for an improvement.

CAUTION:
The flexible joint must never be separated from the drive shaft since the joint and drive shaft have been balanced as an assembly. Do not loosen the flexible joint to drive shaft retaining bolts and nuts (Illustration 5).

1. Ensure that the wheels are securely held and that the transmission selector is in the Neutral position.





2. Remove the three bolts (Illustration 5) retaining the flexible joint and drive shaft to the pinion yoke and then detach the joint from the yoke.

3. Raise a rear wheel to allow the pinion to rotate.

4. Remove and discard the retaining bolts from the drive shaft center bearing crossmember (Illustration 4), and lower the drive shaft and crossmember assembly to allow the drive shaft coupling to withdraw from the pinion nose.





5. Mount a dial indicator to the final drive unit with the gauge stylus in contact with the pinion spigot, as shown in Illustration 6.

6. Carefully rotate the raised wheel to turn the pinion while noting the gauge reading.

7. If the gauge records a spigot run-out of greater than 0.003 in. (0.07 mm), the final drive unit must be replaced.

8. When reinstalling the drive shaft center bearing crossmember, use NEW retaining bolts.

9. Rotate the drive shaft 120 degrees in engine rotation from the paint spot on the final drive yoke, reinstall the drive shaft on the final drive yoke. Then install and torque the bolts to 52.4-61.2 lb. ft. (71-83 Nm.)

10. Recheck the drive shaft alignment and adjust if necessary. Road test the vehicle.

11. If the vehicle still exhibits vibration on the road test, rephase the drive shaft an additional 120 degrees in the direction of engine rotation relative to the pinon yoke.

12. Road test the vehicle. If the procedure still has not been successful, install a new drive shaft.

NOTE:
Once the vibration condition is satisfactory, or if a new drive shaft is installed, install NEW nuts on the bolts retaining the flexible coupling to the drive flange.