Re: A-TRAC: help me out!
Regarding the Torsen differential, I remember when Trant Jarman was the technical editor at Automobile Magazine back in the mid '80s. He and I worked together at Cars and Concepts and he heard that I'd written a paper at college about the Torsen. He grabbed me by the arm and sat me down and said, "you don't leave this table until I understand how that works!" My explanation was essentially similar to the first video linked above.
Amazing thing, the Torsen. I wish that more than just the MT FJ came with them. But, since the assumption was that most sold would be AT, and most of them would be only for grocery getting and commuting, they saved the money (Torsens are pretty expensive) and only spent it on the MT models, which would surely almost all go to hard core truckers. Also the open AT center diff allowed slightly higher mpg for the CAFE targets on the higher volume version.
At least, that was how things looked way back in '05. Today pretty much all anyone buys anymore are AT, but there you go.
Fun fact: the highest % ratio of MT equipped vehicles sold today is the Toyota FRS. Not Porsche, not Ferrari, or anything like that. No, the highest % MT is currently the FRS. Well, that and the Lotus Elise, but I think those aren't even available in anything other than MT.
Additional fun fact: the rear diff in an FRS is a Torsen.
Norm "manual forever" Kerr