I witnessed part of a 4x4 training course - and the instructor mentioned something that caught me off guard: most 4 wheel drives aren't 4 wheel drives at all! (Goes to show you how much I knew at the time. )
For example, in nearly every All Wheel Drive vehicle (the ones where you can't select 2WD) exists the "soccer mom 4wd" that is very effective for slippery surfaces that you would encounter on the occasional ski or camping trip, but can quickly disappoint you on a trail. There is a good reason for this: the transfer case needs to enable the front axle to operate at a different speed than the rear axle (for sharp turns) without damaging the transfer case. It also shocked me to learn that Jeep was using this technology in their newer Grand Cherokees (boy was I disappointed, because I love my 88 that has a selectable full or part time option. )
It boils down to two main types: Full Time 4WD and Part Time 4WD. These translate to "Full time road operation" and "Part of the time road operation. " With the Part Time, you should not make any sharp turns on dry concrete due to damage to the transfer case.
Our trucks use PART TIME transfer cases. Here are the differences:
FULL TIME - the transfer case allows slippage, which is good for on road use when conditions get a little freaky and you don't want to worry about drivetrain damage. However, you will not get maximum traction off road because you can have a condition where either only your front axle or rear axle are spinning. If you have Open Differentials there is still the possibility that you can have only ONE tire spinning. If you have Limited slip differentials then you'll have one tire spinning up until the limited slip kicks in, then you can have a condition where you have 2 tires spinning on the same axle. If you have lockers, you will always at least have 2 tires spinning on the same axle.
PART TIME - Is like putting a locker in the T-Case (sometimes called the Center Differential. ) With Open Differentials, you get at least 2 wheels spinning, but on different axles. With LimitedSlip, you'll start with 2 and maybe end up with 3 or more. If you have lockers, you have the ultimate configuration - you can guarantee all 4 wheels will transfer power to the ground. I read this is not the ultimate configuration for snow and ice however - but more for extreme terrain where the vehicle will be placed at different angles.
For wheeling, in my experience with my Dodge the limited slip is quite poor. It hurts the ego a bit to watch Ford and Chevy's (bone stock) getting through obstacles (simple example: back up a hill on wet grass in 2WD) I have to really strategize my path. I have been in a 2WD condition where one wheel had nearly no weight on it. Having the e-brake all the way to the floor still wasn't enough to get power to the other tire. However, if both tires have contact, it won't hesitate to spin both tires under load. With AAM axles at least, I'm not yet aware of a locker option yet.
Don't get me wrong though, the design of the limited slip is extremely good and strong - which is probably the best solution for such a heavy duty axle. I know the new powerwagon has electronic lockers, but at the time I was shopping they didn't have a diesel option haha. You may be able to swap out the axles if you can find one - but I think they only came with the 10. 5" axle - which I wouldn't recommend behind the diesel without some work.
Power Wagon Registry
However the 9. 5's seem the same hmmmm.....
So yes - even with 4WD, there's still the possibility of 1WD haha
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