Originally Posted by me1234

Yes, this has been gone over multiple times, but I'll chime in cause I'm bored and feel like being helpful lol. An open differential, which is standard on most 2wds and 4x4s, split power evenly between each wheel, until one loses traction then power is transferred to the wheel with the least traction. The reason most vehicles are equipped with open differentials is 1) they're cheap to make and 2) they allow for each wheel to rotate at a different speed throughout turn, stopping them front hopping mid-turn and making various horrible noises In a 4x4 with both front and rear open differentials, the front and rear wheel with the least traction will provide power. Basically its a 2x4. Open diff 2wds are really 1x4s. Now, open diff 4wds are useful because there is a chance that both front wheels or rear wheels will have traction when the other end doesn't and the truck can get out. However, if one front wheel has no traction, and one rear wheel has no traction at the same time, an open diff 4x4 is stuck. OP, the reason both your rear wheels spun and only one front wheel did, is because your rear differential is not an open diff, it is a limited-slip differential. Limited slip differentials are different from open diffs because they allow for different wheel speeds, but after a certain point will lock up and give power to both wheels. This is accomplished from friction plates(called clutch packs) in the differential that allow for force to be transferred to both wheels. Limited slip differentials do have their limits and setbacks though. If too much throttle is given, it can actually beat the friction plates and cause the wheel with least traction to spin. While this is happening, the clutch plates are rapidly being worn down, weakening them. Since the plates are made of a friction material, they also have to be replaced after a while or the differential will not split the traction. Limited slip differentials are normally only available in the rear differential from the factory. These differentials are also pretty weak for serious off-roading, but usually strong enough for the average persons needs. Many aftermarket limited slip differentials do exist though. The highest rated being the Eaton Helical limited slip differential (also known as a Detroit Trueteac). This differential is much stronger than the factory differential and uses helical gears instead of friction plates to actually transfer more power to the wheel with less traction and is totally road friendly. These gears will supposedly never wear out like the friction plates in standard limited slip differentials and are supposed to be maintenance free(from what i've read on multiple forums, this appears to be true). The Detroit Truetrac is also available for front and rear applications and can give you power to all 4 wheels. Other differential types do exist. A favorite among off-roaders is to use a locker in both the front and rear differential. A locker locks both front and rear axles and transfers power evenly to both. This will give the affect most people assume they have when they put their truck into 4x4 in that all 4 wheels give power no matter the traction. The downsides to a locker: 1) they don't allow different wheel speeds and thus can cause wheel hop in the middle of a turn. 2) if an in-experienced driver uses a locker and gives too much throttle to get unstuck, the stress can be too great for an unmodified axle and actually break it. But they are favored for a reason, because, quite frankly, they get the job done(unless you're truly in deep &$&). Then only a tow strap and a friend with another vehicle can help you. Multiple types of lockers exist, some are always on, while others can be turned off an on either electrically or using an air compressor mounted to the differential. These selectable lockers have the true 4x4 advantage when turned on, but act as an open differential when turned off.