Companion Flange


  • The driveshaft connects to the differential either using a companion flange or a pinion yoke.
  • Check for obvious damage, bends, and missing weights. Weight will either be on the front of a flange or the outside depending on whether the correction was for flange runout or differential balance.
When there is a weight on a pinion flange, it was put there to correct for runout.
  • Runout on the flange is checked with a dial indicator. It is limited to 0.0006” when there is no weight on the flange.
  • A hardened pinion seal can wear a groove in the mating surface of the companion flange or pinion yoke. the flange will need to be removed and visually inspected. if a wear groove exists, there may be a repair sleeve available to avoid the cost of replacing the part. replace the pinion seal.
Look for a wear groove caused by a hardened pinion seal rubbing against the pinion yoke (top) or companion flange (bottom).