The rotating parts of a Model T are all out of balance from the front of the engine to the pinion gear from a little to a bunch.
I had never checked a drive shaft but after seeing what the 500 boys go to I wanted to know how far a drive shaft was out of balance.
After checking several shafts one was found that will be used. It was chucked in the lathe and carefully centered to the bearings. The shaft itself was about 7 thou off center to the bearings. This put 7 thou of weight on one side of the shaft all the way across.
Took my blade balancer apart and extended it to 48" between rails to hit the bearing surfaces of the drive shaft. Then started taping weights to the shaft to counter balance the heavy side. It took a little over an ounce.
The math boys can think out how much pressure would be pushing the drive shaft into a curve at say 2000rpm in high gear. Just a few pounds of hand pressure in the lathe will off set the center of the shaft over 10 thou
After some thought the heavy side of the shaft was ground off end to end. It took about twenty minutes to put it in balance.
Paul, driveline balancing is certainly an overlooked thing. I have found that balancing the driveline really helps to make a smooth driving T. One caution: Check your driveline for straightness after grinding the length of it. I have found that it works better (from a warp-age standpoint) to add weight to the light side rather than grind the heavy side.
Thought about adding weight Tom then thought welding a weight might distort more. I will check it in the lathe-- Thanks!