Seems to switch in and out of four wheel drive while driving

Okay, I gotcha. What type of 4x4 setup do you have? Is it a push button or other automatic/electronic setup, or is it a manual setup with a shifter that you pull on? I am guessing that it is an electronic setup. If so, what we are looking at is likely a problem with the transfer case control module, or a short in the actuator/electric motor that engages and disengages the front wheels. So let me know which it is and we'll go from there. I will do more research and dig up diagrams and such for you.

Yours is the live axle assembly. Basically, the connect/disconnect is done at the transfer case, instead of at the hub, which means that you do not have to manually lock and unlock the hubs.

The images below describe how the transfer case works.

You might try simply unplugging the 4x4 switch and see if anything changes. I have seen 4x4 problems (such as unwanted operation) to simply be a short in the switch. If it stops when the switch is out, then we can (1) look into further testing of the switch or (2) simply get one from eBay or the local salvage yard.

Sorry. I just realized that you are talking about a manual transmission, and Prodemand and AllData do not show a manual transmission as an option for a 2002 Ranger with the 4.0L engine and 4x4. I completely missed that. The 2002 Ranger with the 3.0L engine and 4x4 does show as having a manual transmission option. Neither shows having a 4x4 setup that is run by a lever instead of an electrical switch. So I do not know exactly what is going on there, so I will try flying blind until I can figure it out. It is possible that this is a really very super simple fix. You might just need to get under the vehicle and grease the various linkages on the transfer case. Sometimes, when these things get dirty, they just do not move quite like they are supposed to. Especially with manual shift setups. You might check the linkages and make sure that the are tight, and not out of adjustment (hard to tell, I know, but give it a shot).

In the meantime, if you can get the VIN# for me, it might help me figure out exactly what is what here. And is this a US market truck, or is it some other market?

Thanks for bearing with me. Let me know.

Has there been any work done on it in the past? In particular has anything been done with the differentials? Because if so, it is possible that the gear ratios are not matched up.

It sounds like the encoder motor is not pushing the transfer case all the way into gear. I would start by changing it. Here are diagrams to help you see how the system works and how to change the actuator. Check out the diagrams (below). Please let us know what happens.

Cheers, Ken

I am thinking maybe it is something like an Eaton positive traction differential popping in and out (slipping).

Just a guess, my friend had one in the rear of his 1981 CJ5, when he made hard turns, it sounded like he sheared an axle in half each time!

The Medic

I did a little more looking for a video of the Eaton making the racket and jolt.

So far I found no video yet.

The one I am referring to is not the "Elocker", My friend's has no electric to it.

I did find this video showing operation. It kind of looks like a pencil sharpener. I would say the worm-like gears are what does the jerk when they snake past each other.

https://www.youtube.com/watch?v=lZmsY2YvVsc

Pop your differential cover off and see if the differential has the pencil sharpener goodies instead of the normal side gears.

The Medic

If this unit does not have clutches in it, it probably did not require a friction modifier additive. My buddy's Eaton unit did not require it.

The Trac-Loc limited slip differential did use friction modifier in CJs, they had side clutch packs in them (other vehicles had similar set-ups). For sure yours is not Trac-Loc.

I do not know what you have, so I do no know if it has clutches or similar components inside.

Is there a manufacturer name or model stamped or embossed on the unit?

I will look stuff up for you if you can get me some information.

The Medic

That is the tag on the outside, probably the original set-up.

I am guessing this is not original innards? Anything stamped on the big ole spindle on the inside (edges or the flat parts)?

Surely they were proud enough to put their name on it somewhere.

The Medic

Can I have your VIN? It will get me to the right references fast.

The Medic