SWCDuke

Well, it's only been thirty some-odd years, but author David Kimble tells the whole story in the November Road & Track, and it turns out that is wasn't really and "automatic" after all, but a conventional dog clutch crashbox with a torque converter designed and built by GM Muncie. Perhaps the first version that only had a single forward speed could be called an automatic a la the original Buick Dynaflow that only offered a single speed in "drive". (A lower reduction was available by manually engaging "L" on the gear selector lever.)

As time and development progressed a second and then third speed was added along with a lockup converter feature. A fourth speed was planned, but development was cut short when Jim Hall got fed up and quit Can-Am racing following SCCA's banning of the Chaparral 2H "vacuum clearner" car.

Phil Hill offers driving experiences in a sidebar. Upshifting was accomplished as with a conventional crashbox and clutch - just lift and flick the lever, but he didn't say anything about downshiftiing. With a crash box you usually have to double clutch to keep from damaging the dogs and creating a big transient torque reaction that can upset rear stability.

Duke