Part Time 4WD question

01_XJ · Jan 13, 2006

so i have a 2001 XJ with the part time 4wd. call me dumb or whatever but i don't really understand what this means. is it like an AWD systen on a CRV, Rav4 or something like that, where it only powers the front when it needs it or what? from browsing sites, it looks like i have the NP242 TC, and when i put it in 4wd it lights up "part time" on the dash.

5-90 · Jan 13, 2006

"Part Time" means just that - you use it part of the time.

PT4WD is meant to be used when it's needed, using it all the time will result in transfer case damage. You can use it in the wet, snow, mud, or when crawling all you want - but leave it engaged on dry pavement or in places where the tyres won't slip, and you'll be replacing a chain at the very least.

You're thinking "Full Time 4WD" = All Wheel Drive - you get that with the NP242 transfer case. If you do NOT have the FT4WD setting, then you have the NP231, most likely.

Again, do not leave this engaged on dry pavement! Save it for when you'll need four-wheel drive. Engaging it for short distances (say, several dozen yards or so to test it) won't damage anything, nor will engaging it with all four wheels off the ground, but if you leave it on on dry roadways, you're going to break something (what and how much depends on several factors - you'll eventually stretch/snap the tcase chain at the very least. Some here have blown up their tcases from a failed chain - so that might happen to you as well...)

5-90

01_XJ · Jan 13, 2006

sooo... the 242 is better, right? should i consider swapping later or will the 231 be ok. my plans are basically gonna be just to have 31"s, max 33"s, prob max 5" lift. i am in school so i only will go wheelin maybe twice a month, mostly dunes, unless i start goin with some of the guys on here out to borrego springs and stuff.

scoobyxj · Jan 13, 2006

Both are good the 231 ( what yours & most XJ's come with) is just the standerd transfer case. The 242 is the upgraided transfer case that is offerd in the higher trim levels. As far as which one is better I don't think it really matters on a strength standpoint. However the 242 will allow four wheel drive on dry pavement, and the ability to lock both front/rear axles together. Where as the 231 just offers locked front/ rear axles. Also by locked axles I mean from front to rear not left tire to right tire

Tim_MN · Jan 13, 2006

Go to the JEEP website and watch the video animation about 4x4 systems. The Liberty and the Cherokee have the exact same 4x4 system and control levers.
.
JEEP 4x4 systems = http://www.jeep.com/liberty/4wd_capability.html

dmillion · Jan 13, 2006

01_XJ said:
sooo... the 242 is better, right?

No. The 242 is different. That's all. For some people the addition of the full-time 4WD setting might be useful. For others it might not be. Neither is "better" than the other.

bj-666 · Jan 13, 2006

dmillion said:
No. The 242 is different. That's all. For some people the addition of the full-time 4WD setting might be useful. For others it might not be. Neither is "better" than the other.

the 242 does have a wider chain and gears as well as a better planitary gear set. its down side is there is no HD SYE for it yet just a hack and tap.

o yea if ya have any other questions on 241vs231 look here

01_XJ · Jan 13, 2006

Thanks for the info. i doubt i'll ever need 4wd on the road here in San Diego, so i guess i'm good with the 231.

jpony645 · Jan 20, 2006

I'm glad I found this finally. I've been wondering about how the 242 worked and when FT/PT could be used.

Thanks!

AREYOULIVING · Feb 20, 2006

So basically, 4wheel Part time means that front and rear DS are locked together at all times no slipping. 4wheel fulltime front and rear DS are connected via a limited slip. Is this correct?? So the 242 has viscous coupler or clutch packs that are engaged during 4wheel Fulltime? Does it bypass this coupler when in 4low?

crawldaddy · Mar 1, 2006

mostly correct.

there's a differential in the np242...it's not a vc or a clutch pack...it's a real AWD system, but it has Ujoints instead of CV joints in the front axle, so the xj will "cog" at the steering wheel when in tight turns. it also has a true low range which AWD systems do not include. in part-time (both hi and lo ranges) the center diff is locked, and the result is a 50/50 torque split between the front and rear. if you don't have lockers in the axle diffs, then you get two wheels pulling - same as the np231 case.

the np242 is also used in the civy H1 hummer (i believe the Mil version uses a bigger case with more oil capacity, but it's still the 242).

the np242 is rated at about twice the torque and loading that the xj can produce.

GirlScout1 · Mar 1, 2006

You could switch to a 242 for the whole FT4WD option but I think you would be just throwing money away. Ask yourself if you really need that option. For the most part I keep mine in 2WD until I need it. Then usually it's right into 4LO. Most anything else can be handled with skill though I will be going to a 2LO this summer.

crawldaddy · Mar 2, 2006

Back to the first question: It looks like a 242, but it lights-up "part-time" on the dash....is it a 242, and how can you tell?

XJs come with either the 231 or the 242 case. The 242 was used almost exclusively on the higher trim level units like the Limited, while the 231 was used on all the others, and on ALL manual transmission XJs. If you have a lower trim level XJ, then it's most likely a 231 case.

They look pretty much the same, and you don't want to crawl under there anyway, do you?

the shift pattern for a 242 is: 2-F-P-N-L
the shift pattern for a 231 is: 2---P-N-L

On the 242, there will be two distinct detents between 2 and N, but only one on the 231. On the 242, the F position engages when the lever is only about an inch above the 2 position. If you feel a detent at about that position, but no light shows-up on the dash, then maybe you have a 242 and a dead light bulb. Not likely, but worth checking.

If you have a 231 and just can't live without a 242, sell your XJ and buy one that already has a 242 - it's a waste of time to change one for the other if the one in the truck is working...and it's too darn easy to sell one and buy another...and another... Just check my driveway.

bobb · Mar 2, 2006

crawldaddy said:
Back to the first question: It looks like a 242, but it lights-up "part-time" on the dash....is it a 242, and how can you tell?

XJs come with either the 231 or the 242 case. The 242 was used almost exclusively on the higher trim level units like the Limited, while the 231 was used on all the others, and on ALL manual transmission XJs. If you have a lower trim level XJ, then it's most likely a 231 case.

They look pretty much the same, and you don't want to crawl under there anyway, do you?

the shift pattern for a 242 is: 2-F-P-N-L
the shift pattern for a 231 is: 2---P-N-L

On the 242, there will be two distinct detents between 2 and N, but only one on the 231. On the 242, the F position engages when the lever is only about an inch above the 2 position. If you feel a detent at about that position, but no light shows-up on the dash, then maybe you have a 242 and a dead light bulb. Not likely, but worth checking.

If you have a 231 and just can't live without a 242, sell your XJ and buy one that already has a 242 - it's a waste of time to change one for the other if the one in the truck is working...and it's too darn easy to sell one and buy another...and another... Just check my driveway.

You're a little backwards on that. It's 2-P-F-N-L on the 242.

SourApple · Mar 2, 2006

crawldaddy said:
mostly correct.

there's a differential in the np242...it's not a vc or a clutch pack...it's a real AWD system, but it has Ujoints instead of CV joints in the front axle, so the xj will "cog" at the steering wheel when in tight turns. it also has a true low range which AWD systems do not include. in part-time (both hi and lo ranges) the center diff is locked, and the result is a 50/50 torque split between the front and rear. if you don't have lockers in the axle diffs, then you get two wheels pulling - same as the np231 case.

the np242 is also used in the civy H1 hummer (i believe the Mil version uses a bigger case with more oil capacity, but it's still the 242).

the np242 is rated at about twice the torque and loading that the xj can produce.

not to sounds like a fool, does the 231 have a 50/50 torque spit too?

crawldaddy · Mar 3, 2006

bobb said:
You're a little backwards on that. It's 2-P-F-N-L on the 242.

Nope. It's as I had stated: 2-F-P-N-L

The P and L are each one click away from N - it's like they're pairs.

Go out in the driveway and check yours.

crawldaddy · Mar 3, 2006

SourApple said:
not to sounds like a fool, does the 231 have a 50/50 torque spit too?

Yes.

Interestingly, the 242 does 48% front and 52% rear when in FT4. I would like to know how that happens.

bobb · Mar 3, 2006

crawldaddy said:
Nope. It's as I had stated: 2-F-P-N-L

The P and L are each one click away from N - it's like they're pairs.

Go out in the driveway and check yours.

Mine's 2-P-F-N-L . Is this something that's different between years? Mine's a 97. I have a picture, but i can't attach it and don't have an image server.

crawldaddy · Mar 4, 2006

bobb said:
Mine's 2-P-F-N-L . Is this something that's different between years? Mine's a 97. I have a picture, but i can't attach it and don't have an image server.

Bobb,

There was this little voice in my head telling ME to go out in the driveway and check MINE before posting, but my feet were already warm, and the single-malt scotch was exceptionally tasty, and I was ABSOLUTELY sure...

Imagine the sight! My face flushed like a toilet as I looked down at that friendly little lever to the left of the shifter...

You are correct, it is 2-P-F-N-L.

I was wrong, and I shall never pontificate again.

Bill

AREYOULIVING · Mar 7, 2006

Has anyone had to rebuild a 242?? What are the parts that wear out?

The reason I ask is that a week ago I was driving home when a horrible grinding and popping started. I pulled into a four wheel drive shop and they diagnosed my 242 as the problem. They had a decent deal on a 231 w/ SYE and heavy duty DS. As it turns out the rear U-jopint was also bad (6" of lift and no SYE will do that) I'm pleased with my swap, but miss the AWD option. And I have this 242 sitting here that might not be bad. So what do I look for in a bad 242?

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