Quote:
Originally Posted by EricH
Wheelbase. Shorter wheelbase means easier turning. 6WD drop and 8WD (2-drop) are common because they provide a shorter wheelbase, while still maintaining the same trackwidth--turning is easier, and you don't have to worry as much about losing traction or tipping as if you just built a smaller 4WD.
That being said, many of the 6WD and 8WD teams started doing it when the drivetrains were 36"x30" or 38"x28", when the high wheelbase/trackwidth ratio really showed up--as "bouncing" in many 4WDs. Once you have something relatively standard, why change it?
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Actually the main reason that a drop center 6wd turns easier is not the shorter effective wheelbase, it is the fact that the normal force and thus the scrub friction is lower on the outer set of wheels that are in contact with the ground assuming that the CoG is near the center wheels. A 4wd's turning ability can be greatly improved by putting the CoG very close to one end because it also reduces the normal force and thus scrub friction on the set of wheels farther away from the CoG. Of course offsetting the CoG dramatically may not be feasible and it increases the likelihood of tipping.