Confused about 4wd

I have a 96 cherokee 4wd 4.0. I have the PART TIME 4WD transfer case. I got it into some mud the other day and my front driver side wheel and my rear passenger side wheel were both spinning. The other 2 wheels were not Spinning. I must have to wrong idea about what 4wd means? Is this how it is suposse to be or is something broke? I barely made it our of the mud. ANY help would be appreiated. My friend has a 90 model that has 4wd part time and 4wd fulltime, would this do better in mud? If si i might change my transfer case out. If my truck is not broke and it is suppose to be like that then are ALL 4wd vehicles like that? meaning not all 4 wheels will turn? What about trucks that have locking hubs are they better? Are they a true 4wd. Please educate me. I have searched the forums but i am still confused. Thansk in advance.

TJ

What you observed is common with 4 wheel drive when the axles don't have a supplemental traction device such as a "limited slip" or "lockers".
You may have noticed that in a 2wd vehicle it is easy to get stuck when one tire gets in mud or on a slippery surface. It is the nature of the differential to apply equal torque to both drive wheels. If one wheel is on ice and it takes only a small amount of torque to spin it, the other wheel receives the same amount of torque (next to none). So essentially you resort to 1 wheel drive, the one that spins easiest. In 4 wheel drive you are driving both the front and back axle. The differential for both of them does the same thing as the 2wd we observed above. So if one back tire has no traction and one front tire has no traction, you end up in the same situation except that you are spinning one in front and one in back. Why a 4wd vehicle would ever be sold (or bought) without some sort of suplemental traction aid, I will never know. I got stuck with a Durango rental one time b/c as I crested the hill I was at an angle that lifted the weight off the right front and left rear tire and left them both spinning. Adding a "limited slip" or other device to the back axle will greatly enhance your off road traction. Some people put a device on both the front and back axle. My Cherokee has a Dana "trak-lok" rearend and standard open differential in the front. I've never gotten it stuck or even came close.

Neon or anyone else;


where can i get a Dana "trak-lok" rearend at?

Neon Rt is correct about your differentials being open. Nothing wrong with yours, its just the nature of the beast. Most all stock 4X4 are this way standard but most also offer a limited slip differential as an option. The Trac Loc is the limited slip that is optional for Jeep and Chrysler products.
The Trac loc isnt a very aggresive limited slip and it has clutches that can wear out after a few thousand miles. It will cost you around $400-$500 for parts and labor to have one put in your rear axle. Search the www for "differentials", try Randys Ring and Pinion or Drivetrain Direct. There are literally hundreds of places to buy differentials. Personally I wouldnt waste the money on a Trac Loc. If you almost got stuck in mud open, you will almost get stuck in mud with the Trac Loc, its not going to make much difference at all. If you are going to spend the money of installing it, and you want a limited slip, get a True Trac, if its available for you axle. Its a little more aggresive and should last you forever.
Changing transfer cases is not going to do anything for you in the mud. The fulltime option has an open differential in the t-case so you really only have true one wheel drive while in full time. Locking hubs have nothing to do with open differentials. Your XJ hubs are always locked.