Originally Posted by klown
I guess I don't understand, if both the front wheels are spinning at the same speed when turning, wouldn't that make it a front locker?
They'll never be turning at the same speed or distance while turning. The inside wheel will always be turning less and cover less distance than the outside wheel. That's why the differential is OPEN because its designed to allow each wheel to spin freely at its own rate especially for turning.
Majority of the reason why you have such a hard time turning while in 4WD is mostly due to the CV joints at each front wheel. In 2wd, the CV joints are *going along for the ride* with no torque being applied to them. In 4WD - the CV joints are 'driven' and thus experiencing torque.
Imagine these swivel sockets as your CV joints. When they are perfectly straight (up/down), they're easier to spin without a lot of pressure. But if you bend them (as seen in the picture) and try to spin them, they won't spin as easily. Same scenario with the CV joints.
Although - on a side note - you'd think the OPEN differential would prevent this CV joint bind-up from happening. The front axle shafts themselves never transfer that bind-up pressure to the front differential - so it can't compensate for it.