Transfer Case Question NP242 vs NP231

[maxbraketorque]

Seems a bit puzzling to me that its not going into 4PT. Its necessary to pass through 4PT to get to 4FT. Would seem strange for the TC to be in 4FT when its set to 4PT. Would be nice if there was a clear diagram of the NP242 to show the torque transfer path in each of the different modes, but I haven't been able to find one. Have you tried disconnecting the linkage from the TC shifter arm to see if the TC can be shifted into 4PT using you hand from underneath?

 

[1990JEEPXJ]

Seems a bit puzzling to me that its not going into 4PT. Its necessary to pass through 4PT to get to 4FT. Would seem strange for the TC to be in 4FT when its set to 4PT. Would be nice if there was a clear diagram of the NP242 to show the torque transfer path in each of the different modes, but I haven't been able to find one. Have you tried disconnecting the linkage from the TC shifter arm to see if the TC can be shifted into 4PT using you hand from underneath?

The full time mode just makes the transfer case an open differential like an axle so there is no real regulation of torque as it will only be traction dependent and send power to the axle with least resistance. In theory, you could still spin only one tire while in full time. There are no clutches to assist with splitting the torque front and rear.

 

[maxbraketorque]

Yep, I understand that aspect. I was trying to find info on the physical design of the NP242 diff to show how it switches from differential mode to locked mode.

 

[Rob Mayercik]

Can you download a service manual from NewProcess/NewVentureGear?

If memory serves, the XJ FSM has some degree of rebuilding information, anything useful in there on this?

 

[75SV1]

Can you download a service manual from NewProcess/NewVentureGear?

If memory serves, the XJ FSM has some degree of rebuilding information, anything useful in there on this?

I am attempting to rebuild a NP242. I have an '00 FSM. It seems complete on the rebuild procedure.

 

[maxbraketorque]

If you've got an NP242 on the bench, I would love to see some photos of the component layout that produces 4FT and 4PT.

 

[Lost_Wrench]

I would also love to see that.

 

[Jason77]

Same here, I’ve rebuilt a 231 but never seen a 242 apart. I’d like to see how it’s different.


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[Lost_Wrench]

Update:

So my NP242 T-Case in the '98 XJ was only operating in 2WD or Full Time. Part Time High and Low were not engaging, despite the dash lights showing the correct position for all. I finally got around to diagnosing yesterday and I feel like a dummy, but the simplest solutions are often the likeliest culprits. I drained the T-Case and there was less than a quart (20oz) of nasty dark fluid. Filled up with ATF and now all 4x4 ranges work and shift fine. Thanks everyone, Tim_MN and whoever else recommended a fluid change were correct.

I purchased this Jeep last September and all 4x4 ranges were working until December-ish. Makes me wonder if the fluid had ever been changed. It was so dark and disgusting I wouldn't be surprised if it was old gear or motor oil from someone topping it off with whatever they had in the garage. T-Case doesn't appear to have been leaking at all so who knows why it was so low? Why Full Time still worked with such low fluid is a mystery that only those with intimate knowledge of the NP242 would probably know. If that's you please share. Thanks all!

 

[cruiser54]

Please don't take offense, but I'm gonna use your post as an example.

ALWAYS check fluid level and condition on any "new to you" vehicle.

do a used car inspection like the dealers do on trade-ins.

 

[Lost_Wrench]

Please don't take offense, but I'm gonna use your post as an example.

ALWAYS check fluid level and condition on any "new to you" vehicle.

do a used car inspection like the dealers do on trade-ins.

I wouldn't be a good example then because I did...as soon as I got it home in fact. At that time I could put my finger inside the T-Case fill plug and feel fluid. Sometimes it's hard to tell how dirty fluid is from that type of check vs when just I drained it all into a clear container. Plus, the 4x4 was working fine in all ranges at that point in time so I wasn't suspecting anything abnormal. Why their was so much less fluid this time? I dont know.. Do T-Cases ever burn fluid? Maybe it is leaking slowly from somewhere and I just can't tell.

 

[Lost_Wrench]

To further clarify, when I first test drove it I could feel the wheels binding in Part Time when turning on dry pavement, like it should. It wasn't until months later when there was snow on the ground that I noticed Part Time 4x4 wasn't working correctly. When testing it one day it sometimes felt the same as Full Time, and sometimes just felt like it was still in 2wd. So in just a few months time of normal driving the fluid level decreased substantially without the 4x4 system being used very much in that timeframe. Hopefully the internal seals and bearings aren't too damaged from the fluid being so low. If I'm to be used as a bad example for something - which is fine - it's for not checking the fluid as soon as I noticed a problem.

 

[cruiser54]

Transfer case holds very little fluid to begin with. Less than a quart.
It coulda had a lot of miles on it. Interval for changing is every 30,000 miles under normal usage.

 

[Unclewolverine]

My 242 takes about a quart and a half, but export ones are supposed to be different somehow...

 

[Jim Malcolm]

I provided an explanation of how the 4FT vs 4PT works on another Cherokee specific forum since suitable pictures were previously posted there; I don't have the means to host my own pictures and might as well add to the conversation vs fragmenting it. Search for "242 Transfer Case Modes"...