I'm rebuilding the drive train and found this done to the drive shaft. My question is: Should I be concerned about the grinding and drilled dimple leading to torsional stresses being set up. Don't want a drive shaft flailing about in the torque tube.
My guess is that it was done to balance the shaft. I don't think it would be likely to cause a failure.
That was my first thought. The shaft has .008 runout.
I've seen the same on quite a few drive shafts. I always though the flat spot was created to drill a small hole in the driveshaft so it could be straightened.
Could be flat spot was added prior to a Brinnell hardness reading being taken.
I think Nick may have hit upon the answer. It was customary to grind a flat before applying the a load to the indenter ball when using the Brinell hardness method. Unless there is a consensus otherwise, I am inclined to use the shaft.
Nick is 100% correct.
Brinell hardness was my first thought.
It is a Brinell check spot, I have done thousands.