MTFCA Forum

I'm about to purchase a 1993 Jeep YJ from a friend. It's 4WD, has a manual transmission, winch, and lots of bells and whistles. It's in GREAT shape and is for my grandson.

My Question:
I'm FAR FROM and expert on this stuff, but I think I know that a standard rear end (differential) actually puts power to only one wheel. When stuck in the mud only 1 wheel spins. So, in a 4WD unit, are both "rear ends" (differentials) like that, meaning that in 4WD it's actually only 2 WD, 1 forward and 1 rear? Or are they somehow different and when stuck in the mud all 4 wheels spin?

Thanks for any info!!

Yes Henry, 4X4 is truly one wheel per axle.
Unless you have a locking device such as positraction or a locking spool etc.

Thanks for the reply Dave. That's pretty much what I thought, but was not sure.

I own a Jeep Cherokee, 1991 with 375K miles on it. It is a great vehicle. The jeep you're looking at would come with either "Selec-Trac" or old time lockup (Command-Trac) which gives both front wheels a locked axle. Mine is the older (cheaper) version, Command-Trac and one must be very careful to ONLY use it on slippery surfaces, since when turning, the wheels want to rotate at different speeds and must be allowed to slip on the surface or the axle will tear up. It is WONDERFUL in snow and mud. Both are shift-on-the-fly transmissions and only require stopping if using low range. With the proper All Weather tires these vehicles are almost unstoppable. That said, you will see most Jeeps of this era have front end damage as they have marginal brakes if you run tires larger than intended for the vehicle (my Jeep sports the "I almost avoided it" collision damage to passenger front, as many do). That is the unfortunate part of "unstoppable"! This was a small TRUCK in it's day (not by today's standards) and the lad must know that.

This will give a good overview of what each does, and how...https://en.wikipedia.org/wiki/Jeep_four ... ve_systems

The driver's visor, when folded down will give instructions as to how to use the 4 wheel drive and tell you which system you have.

Thanks for your comments and the link Scott. The one I'm buying belongs to a good friend. He's one of those guys who keeps his equipment in perfect condition. The body is perfect. The engine (4.0 Liter I-6) is a new engine with less than 10,000 miles on it. All the years he had it, service was done ahead of schedule, nothing was left in disrepair, and he didn't "beat" it.

I feel lucky to have access to it. I have a lot to learn about these vehicles, but it's fun!!

Henry

that is going to be a wonderful vehicle!

Scott, you are right about the "Command Trac", but I don't think there was any option on a YJ (Wrangler) transfer case. Should be a New Process NV-231. My 96 Cherokee (XJ) had the same. They work great, just needs to be slick to use "on road".
93 (95) was the last of the "real Jeep". 1996 there was no "Jeep Wrangler" and 97 was the introduction of the TJ, coil spring suspension being the major difference...and round headlights. Chrysler hadn't fooled enough with the 4.0L yet, other than the FI. Very tough and torquey engine.
I actually have a 94 sitting here, waiting to be picked up after some repairs. Very clean for around here. 2.5L 4 banger with no P/S, don't see that often.

Depending on the desired use, locking axles are not needed. If you plan on "serious" muddin, the diffs can be turned into locking units.
The front axle if made into a locker, will make steering difficult if both front tires are spinning.