GM Service Manual Online
For 1990-2009 cars only

A flywheel and torque converter imbalance can be corrected using the following procedure.

  1. Change the position of the torque converter-to-flywheel 120 degrees at a time to cancel out engine and torque converter unbalance.
  2. Recheck in each position for vibration improvements.
  3. Leave the torque converter-to-flywheel in the best balanced position if the unbalanced condition still exists.
  4. Notice: Be sure that the bolts are not bottoming in the holes. If a bolt bottoms the cover could be dented, causing internal clutch facing damage. Always rotate the torque converter by hand after adding washers to check for clearance.

  5. Install a longer flywheel-to-torque converter bolts.
  6. Add and remove washers until the best balance is achieved.
  7. Inspect for missing or loose torque converter-to-flywheel bolts. Replace or tighten as necessary.
  8. Inspect the torque converter for damage or missing balance for weights. Replace the converter if the torque converter is damaged or the balance weights are missing.