Been pondering for a while and can't come up with it. Trying to order parts first to prevent my truck being down for too long...

1998 12 valve NP241

4High - front shaft does spin but I suspect only from the axle itself locking up and turning it...no 4wheel drive but it does move fine in forward gears and in reverse

4Low - same as above but when it hits a certain spot on the gear it starts to, what seems like, the chain jumping teeth on the gear ( best as I can describe it), forward gears seem fine...just starts to give in reverse...
hmm...
What ya think?

-Will

 

Are you sure the collar is sliding over on the CAD? I would first check for vacuum at the CAD, then if that is good take the access cover off and look at the collar in the front axle. It's possible that it is either broken or the splines have worn into a "ramped shape," causing it to jump teeth when enough torque is applied.

Also, while the cover is off you can manually disconnect the front axle and then put it in 4WD and see if you can tun the front shaft. If you can, then you know it's in the Tcase because there is no load applied at tha axle. It's a real simple job popping the cover off, just 4 bolts and she's off. You'll need to seal it up when you put it back together though. Good Luck and post your findings!

 

front axle is working properly...

 

If the front is working properly, I think you're gonna have to dive into the case to find the culprit. I haven't experienced what you have going on, and haven't heard of something similar discussed on here.

 

...anybody have an exploded diagram of this case?...can't seem to locate one on this here new fangled inter-web...

 

this is a chevy one, but they are probably the same

http://www.tbtrans.com/id22.htm#np231

 

I had a similar problem in my old 1500 (NP231, similar to 241), but I could hear grinding occasionally in 4w, would pop out of 2w in reverse. Turned out being the plastic contact pads on the shifter forks melted/broke/etc and shredded the forks and synchro. Sounds internal...have fun.

 

i have similar probs to any one have the exploded diagram of the dodge case the one linked is not the same

 

This post has really piqued my attention, as I think I may be suffering from a similar problem.

SYMPTOMS
-When in 4LO, I get a clunk (sounds like alot chain skipping)

I have checked the vacuum to the front axle shift mechanism (good) and I have checked the condition of the fork and fork guides (good). The axle shaft teeth and engagement collar look to be in good shape, however I can't tell if they are ramped enough to dis-engage when under a torque load...

I suspect that something is going on in my transfer case, and I was hoping to repair this myself when I remove the transmission to give to a rebuild shop (soon). I would be very curious to learn what you find in your repairs, please keep us all posted.

Sean.

 

I just had mine apart. They are pretty simple to take apart and put back together . . . mine had a bad input bearing, half of the ***** were missing.

I think that was allowing the shaft to move around and the chain to jump. Replaced the bearing and all is well.

Take care,
Phill