It's been a VERY long time since I was elbow deep into a Hydramtic (like 1985, I believe), but according to the exploded view from FATSCO, the flywheel, drive torus, and pump cover are all mechanically linked together, and they turn at the same speed. The snout of the input shaft looks like it plugs into the end of the crankshaft. You're probably correct about there being a ball bearing in the crankshaft, as the input shaft won't begin to turn until the driven torus starts to move. A fluid coupling achieves a better lockup than a torque converter, so there will be times during the shift pattern when the crankshaft and the input shaft will be turning virtually the same speed. The very best speed match a torque converter can achieve is 90%- - - - -there's an unavoidable 10% slip built in when an almost 2:1 torque multiplication by the stator happens at low speed. The drive and driven torus assembly is held in close tolerance (but not touching) by a nut and lock washer.

www.fatsco.net/_files/ugd/ffb404_cff3e1e334354578b5fd14dbfecfef31.pdf

Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
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