Ive been arguing with my friends forever. I have a 97' f150 4x4 with the 5.4. In 2HI the passanger side rear tire is the only one that gets power right? In 4HI both rear wheels and the front passanger get power right? What about 4low? So either way 4wd is not truely 4wd?

 

No, not really true. There is a very technical explanation for why the wheels spin the way they do. I'm not sure I even understand it well enough to explain it in those technical terms, but I can explain it in simple layman's terms.

In 2wd, power is supplied through the rear differential to both rear wheels. But (again in simple layman's terms) the differential can get lazy. If one rear wheel has less traction than the other, the differential will take the lazy way and bias the power delivery to that wheel. This will often spin that tire uselessly, while the other tire, which might have better traction, gets little or no power delivered to it. A limited-slip differential can reduce, but not eliminate, this tendancy, and deliver a little more power to the wheel with better traction. Aftermarket devices known as "lockers" can eliminate this tendancy and deliver power equally to both wheels by locking the left and right axle shafts together as a single unit.

If you were to jack your driver side rear wheel off the ground and put it in gear, you will see that that side gets power also. (If you actually try this, be extremely careful regarding which way the truck is pointing, in case the tire on the ground gets enough power to move the truck!)

The same principle applies to the front differential in a 4wd vehicle. Power is delivered to both front tires, but it is possible to sometimes see only one of the two actually spin.

 

4HI and 4LOW are the same, only the gearing changes. All four wheels get power. The problem is that there is a differential between the two front wheels, and a differential between the two rear wheels.

In 2H both rear tires get power, but when traction is exceeded, the rear tire with the least traction will spin. With a differential all power goes to the wheel that has lost traction.

The same goes for the front two wheels in 4HI. There is however, no differential between the front wheels and the rear wheels. You will spin at least one front wheel and one rear wheel at all times.

Now, for example. If you drop one front wheel in the ditch and is suspended and not touching the ground, that front wheel will receive all the power in the front and the other front wheel will not spin. Both rear wheels may still have traction and both will get power and pull.

If for example you drop one front wheel in the ditch and the front end dips down raising one rear wheel off the ground then you have two wheels spinning in in the air and all power goes to those two wheels. In this case is does not matter if those wheels are on the passenger or drivers side, or if your in the ditch on the right or the left. It works the same either way. Hope this helps.

4WD is truely 4WD, but we have to live with the limitations of a differential. You need differentials on dry pavement because when turning all four wheels spin at different speeds.