I found one (NIB) that can be put in my diff. Torsen automatically removes power from the slipping wheel and gives it to the tractive wheel, kind of like an intelligent Posi. What I'm concerned about is loss of fuel mileage. The thing looks like one of those 3-speed hubs that used to come on English bicycles, which were power-robbers (can still remember how strong I felt when I rode my first derailleured bike).

I know they're not the same, but both have lots of internal gears and clutches and so forth, and it makes me wonder what the price of better traction would be. Posi is supposed to cost more in worn tires and more fuel, but I never noticed a huge difference in mileage. I'd never seen a Torsen before, and have never seen anything on this board about them.

Any knowledge or stories of experience appreciated.