Part Time 4x4
CF Veteran




Joined: Jul 2012
Posts: 3,142
Likes: 360
From: Andover, VT
Year: 1999
Model: Cherokee (XJ)
Engine: 4.0 L
Part time indicates that the front and rear driveshafts are locked together, always turning at the same speed. That's why it should only be used "part time."
Jeeps with the np242 TC have a full time option that only engages the front driveshaft when the rear beings to slip. It is okay to use it on dry pavement or "full time."
So basically it shouldn't light up full time, because you don't have the full time option with your np231 tcase.
Jeeps with the np242 TC have a full time option that only engages the front driveshaft when the rear beings to slip. It is okay to use it on dry pavement or "full time."
So basically it shouldn't light up full time, because you don't have the full time option with your np231 tcase.
Senior Member
Joined: Feb 2014
Posts: 854
Likes: 1
From: Minnesota
Year: 1996
Model: Cherokee
Engine: 4.0
Part time indicates that the front and rear driveshafts are locked together, always turning at the same speed. That's why it should only be used "part time."
Jeeps with the np242 TC have a full time option that only engages the front driveshaft when the rear beings to slip. It is okay to use it on dry pavement or "full time."
So basically it shouldn't light up full time, because you don't have the full time option with your np231 tcase.
Jeeps with the np242 TC have a full time option that only engages the front driveshaft when the rear beings to slip. It is okay to use it on dry pavement or "full time."
So basically it shouldn't light up full time, because you don't have the full time option with your np231 tcase.
Seasoned Member
Joined: Dec 2012
Posts: 368
Likes: 1
From: Raleigh, NC
Year: 1999
Model: Cherokee
Engine: 4.0
Not without swapping out the transfer case. The full time option is only available on the NP242 and you have the NP231. The part time means its only active when you engage it ie 4 high or 4 low. You shouldn't drive around all the time with it in 4 high or 4 low since this will cause damage to the transfer case. If you had the NP242 with Full time option you could just leave it in 4x4 all the time without doing damage.
Last edited by jmm0122_; Apr 27, 2015 at 09:51 AM.
Trending Topics
Seasoned Member
Joined: Dec 2012
Posts: 368
Likes: 1
From: Raleigh, NC
Year: 1999
Model: Cherokee
Engine: 4.0
I believe driveshaft's would need to be swapped as well. But honestly why do you want to swap yours out? A little more background info on why you want the full time option would be helpful.
Most XJ's come with NP231's so why go through all the work of swapping to an NP242?
Most XJ's come with NP231's so why go through all the work of swapping to an NP242?
CF Veteran
Joined: Jul 2012
Posts: 3,686
Likes: 6
From: Hudson, FL
Year: 1999
Model: Cherokee
Engine: 4.0L Inline 6
I believe driveshaft's would need to be swapped as well. But honestly why do you want to swap yours out? A little more background info on why you want the full time option would be helpful.
Most XJ's come with NP231's so why go through all the work of swapping to an NP242?
Most XJ's come with NP231's so why go through all the work of swapping to an NP242?
I love my factory 242.
Seasoned Member
Joined: Dec 2012
Posts: 368
Likes: 1
From: Raleigh, NC
Year: 1999
Model: Cherokee
Engine: 4.0
Beach Bum
Joined: Jul 2011
Posts: 6,123
Likes: 22
From: Cape Hatteras, North Carolina
Year: 2000 WJ
Model: Grand Cherokee
Engine: 4.0
Part time indicates that the front and rear driveshafts are locked together, always turning at the same speed. That's why it should only be used "part time."
Jeeps with the np242 TC have a full time option that only engages the front driveshaft when the rear beings to slip. It is okay to use it on dry pavement or "full time."
So basically it shouldn't light up full time, because you don't have the full time option with your np231 tcase.
Jeeps with the np242 TC have a full time option that only engages the front driveshaft when the rear beings to slip. It is okay to use it on dry pavement or "full time."
So basically it shouldn't light up full time, because you don't have the full time option with your np231 tcase.
In FullTime, if you pull up to a step type obstacle with the front tires and try to crawl up it, power will be redistributed to rear while center differential turns instead of front driveline. Opposite in reverse with the rear axle.
In other words, front wheels will not 'power' up and over the obstacle, center differential will turn instead.
Last edited by SteveMongr; Apr 27, 2015 at 10:00 AM.
Thread Starter
Newbie
Joined: Apr 2015
Posts: 19
Likes: 0
From: Franklin,TN
Year: 1996
Model: Cherokee
Engine: 4.0
Im sorry guys i know im sounding like a tool probably with all my short question/answer bs. I bought my jeep as a family vehicle/ DD. I have 3 boys (6,5,3). I took them Wheeling yesterday and among the lengthy list of stuff i want to do to my XJ, i was reading and it would seem that Full time 4x4 would be the way to go and i figured it would be easier to change it over than replace the one i have when it breaks. Plus im in the National Guard and want to make my XJ as close to our Up Armored HMMWV's for fun. We have them set as full time 4x4 and that is another thing that made me want to change it.
CF Veteran
Joined: Jul 2012
Posts: 3,686
Likes: 6
From: Hudson, FL
Year: 1999
Model: Cherokee
Engine: 4.0L Inline 6
I would always want a 242. I run it on the roads often when Florida has its torrential downpours and it keeps me from spinning tires, while still keeping halfway decent speeds. The handling aspect is much better.
The Full Time option basically makes an XJ like a Diablo in terms of handling.
Some people run part time with their 231s on the roads, but I never ever recommend this. Even the factory manual recommends against this. Since you have very limited slippage and your two axles (front and rear) are basically synced together, you could break something doing this if you're not careful. This is the beauty of full time... you can just drive normally.


