[Norm Peterson]

Heat generation and weight, to start with.

For the drag racer (where shift speed is crucial), the first is not a problem and the second can be overcome by means not necessarily available to the road racer (and which brings you right back to the first problem).

With an automatic, you have less control over the actual engagement of the next gear. Harshness is fine (perhaps even preferable) at the dragstrip, where there are only upshifts. But it's not so nice when you've got some cornering load going on simultaneously. You can modulate how hard the clutch grabs and modulate engine rpm to suit when you're doing it all yourself, but not how hard the AT grabs. When you're only trying to do (say) the rev match for a downshift and the tranny is trying to do its thing in response to that manually commanded downshift, it's all too easy to not have things done in sync with each other. It's a do-able but pretty clunky technique so I doubt that many people ever do more than maybe try it out.


Norm