[Turboas]

I know ALOT about cars. Trust me. Each of you is sorta right. The open differentials distribute power to both wheels equally when there is no loss of traction. However, they are not useful for hi-po cars that regularly induce wheel spin because they inherently also distribute power to the wheel with LESS traction, causing one wheel to spin while the other does not rotate at all. That's why limited slip differentials (LSD's) were built. The positrack is a type of LSD. An LSD limits the amount that one wheel can spin more than the other wheel on that axel. So with an LSD one side might only be able to spin 20% more than the other side. It keeps both wheels driven, regardless of the amount of traction there is.

ZZ's have a solid axel, allowing no slip between sides at all. Each rear wheel is spinning the same amount as the other. Putting power to one rear wheel only will make the car slower and handle much, much worse. Try taking one tire off the rear end and leaving the other tires on. You will notice the car now sucks. The ball-bearing idea is very good one. I think that it will reduce friction on the axel and make the car smoother. But BOTH WHEELS NEED POWER!!!. Especially if your running higher than the 1.6 with blue gears, which I hope you are.