A front automatic locker will be essentially invisible in 2WD.
By way of background (for those who don't know me), I'm 61 years old. Bought my first car with a rear limited slip in 1966, and since then have not owned any rear-wheel drive or 4-wheel drive car or truck that didn't have a REAR limited slip. I live in New England, and we do still get snow and ice here in the winter.
If I had a choice between a traction device in the front or the rear (but not both), I would pick rear. Remember that in snow or on ice, there's little enough traction that a Trac-Lok is effectively as locked as a locker -- except that it doesn't unlock when you let off the power. The deal is this, based on an explanation formulated by the late Mark Donohue:
Any tire generates 'X' amount of traction. Doesn't matter what 'X' is, but X = 100%. That traction is used for three things: (1) Acceleration; (2) Deceleration/braking; and (3) turning/lateral acceleration. That X = 100% can be divided between two of the three forces, but can never exceed 100%.
Obviously, you can't be both accelerating and decelerating at the same time, but you can (and do) accelerate and turn at the same time, or decelerate and turn at the same time. Looking at acceleration and turning, the more of that 100% you use for acceleration, the less is available for turning. The more of it you NEED for turning, the less is available for acceleration (or deceleration). Why do you think people "lose it" in turns on slippery roads? Usually, they go into a corner a bit too fast, hang on until they get scared, then when they hit the brakes they suddenly exceed the 100% of however much traction their tires can generate and ... presto ==> spinout.
Therefore, since my vehicles are all steered using the front wheels, I greatly prefer to keep the front wheels available for steering as much as possible, and to use the rear wheels for providing motive force as much as possible. I find that with even a lowly Trac-Lok in the rear axle, having 4WD is almost superfluous. I almost never need it for driving in snow and ice (on the street) in winter.
Yes, the Trac-Lok (or locker) can generate a bit of oversteer. Since I am accustomed to driving with a feather foot in slippery stuff, oversteer has never been uncontrollable. Also I much prefer oversteer rather than understeer, for two reasons. First, oversteer is far easier to correct, and the correction is more natural and instinctive than for understeer. Second, if I have overcooked it into a corner, with understeer I slide off the road nose-first into whatever obstacle is placed conveniently in my path. With oversteer, I may slide into the obstacle sideways or I may spin out completely and slide into it backward. Either way, I'm probably not going to hit it going as fast as I would head-first, and I'll have more crushable body between me and the object (and no engine to shake hands with my feet).
All of which, I guess, is a long-winded way of saying I vote for locking the rear.
arty:
