part time locks the driveshafts together at the t'case so that they both spin at the same rate.

full time lets one shaft spin more or less than the other, it has more clutches and such to do this.

Keep Jeepin!

 

Kurt is right about the full time system....using a differential to relieve the driveline bind inherent in part time systems.

As for the second part of your question, the differential in the t'case acts just like one in an axle. IOW, it will send all the power to the axle that is slipping. Not so on a part time system, like a NP 231 or 207. There is no diff in the transfer case and the case acts like a "locker", splitting the power between the axles equally no matter what the traction situation of the axle is. So, if the fronts have a bite, they'll pull the XJ and the slipping rear along until the rears can grab. /wwwthreads_images/icons/smile.gif

 

Which would you all say is better the 242 or 231? SCRAM And why?

The moment you are born you start to die so buy A Jeep and play hard!!!!!

It's All Out or Nothing At All!!!!!!!

 

Well scram, I think it depends on what you're going to use the Cherokee primarily for. If you are going to use it as a sloppy weather on road driver, then the 242 is the best possible transfercase. The part time 4wd high or low mode could get you out of snowy parallel parking spaces and then shifted into 4wd full time hi, you can travel down those slippery roads without too much worry about "crab walking" onto the side.

Yes, you could use the part time 231 or 207 for this purpose but since the front and rear axles are locked together, you could find yourself on the side of the road in a ditch much easier than if you had a full time 242 or 228. Remember that the axle diffrentials will turn both tires in equal traction conditions. That also is true when neither tire has a grip; both tires will turn spinning the Jeep out of control. So for those of you, like me, who have Command Trac XJs, be careful in 4wd on slippery roads.

For offroad capability, I think the Command Trac cases are better but the 242 is a good compromise between the two. I know in your case that your XJ is used for recreational off roading and it has a 242. I also know that you were very eager to install a locker in the rear axle. Strictly speaking, automatic lockers are a hinderance to the full time mode 4wd on slippery surfaces. On snow, ice or in the rain, the more open your driveline is, the safer the Jeep will be at highway speeds. You have asked around about a locker in the front. IMHO, the ARB would be the best choice because you can still use the fulltime mode and, with the ARB unlocked, the front axle will be open for better control. An auto locker in the front axle on slippery pavement is just plain dangerous.

Of course, we all should be careful on icy roads regardless of whether we have a front wheeldrive, all wheel or 4wd vehicle; no system is 100% fool proof in all cases. I'm very fond of pointing out that the most important part on a Jeep is that grey thing between the ears of the driver. Good Luck!! /wwwthreads_images/icons/smile.gif

 

Well Is it bad to be eager about getting more performance out of your rear diff with a locker???? Do you think its funny that i asked around about a Locker for the front?
I ask many many questions because as most of you know thats how you lern the most. If you think any thing i said was funy then why answer me? SCRAM

The moment you are born you start to die so buy A Jeep and play hard!!!!!

It's All Out or Nothing At All!!!!!!!

 

My reply wasn't meant as a criticism at all. You know what you wanted, a locker, and you went out and got one. More power to you.

No, it isn't bad to be eager about getting something you really wanted. Nor do I think it is funny that you asked about a locker for the front. Notice that I prefaced that sentence with "IMHO", which means "In My Humble Opinion". You don't have to take my advice if you don't want to. I'm just trying to answer the question you asked from my point of view.

By the way, have you ever seen me flame another person on this Forum? No, you haven't. It's not my style. If I didn't like you, Dale, I wouldn't answer your posts at all.

 

Scram with his tail between his legs says he is sorry
I am sorry!! I thought the IMAO ment something else. SCRAM

The moment you are born you start to die so buy A Jeep and play hard!!!!!

It's All Out or Nothing At All!!!!!!!

 

That's OK, scram, I'm not offended at all.

Probably just like you, when I bought my Cherokee so many years ago, I really didn't understand all the ins and outs of the Select Trac/Command Trac systems. That was one of the many things I learned from CJ Dave and the guys over on the SWB board back in the old format when all the Jeep vehicles were grouped together. If I had to do it over again, I'm pretty sure I'd opt for the Select Trac because it would have been more useful to the purpose the Jeep was originally bought for. My wife and I looked at the price of the option and decided we didn't need it. Truth be told, if I'd known that 1 year in the future from then, the 4.0 engine came along, I would have waited for that, too. But that's not what happened. I'm guessing that when you bought your XJ, that the transfer case wasn't so important that you would have walked away from a good buy. You liked the Jeep and bought it. I think we all did that whether we bought it new or used./wwwthreads_images/icons/smile.gif

 

IMHO, I would like to thank EVERYONE who answered my original question....! Confusion is over, and now I can pass this information on to other people who asked me the same thing. Thanks again.

"Its a Geep thing, you wouldnt understand."

 

XJY173 your rite i didnt really know the difference the only advantqage at the time i could c about the 242 is that the axles werent vaccume disconect. But after the Locker thing i dont think it was really an advantage after all.
The other day i had an experience oposite of his. I couldnt go in 4 low poart time and put it in 4 full and it went with ease. OK this is dumb but when i am offroad i dont want to use the wrong mode should i just keep awitching or use 4 part time more? This is my first cherokee ever and with the extra option it kinda leaves me with choices i cant make do to lack of knowlege. Ty SCRAM

The moment you are born you start to die so buy A Jeep and play hard!!!!!

It's All Out or Nothing At All!!!!!!!

 

I cant say enough good things about the command trac as it fits my needs.But yeah,in nasty weather it can get away from you.Just go slow and use good judgement.

1 cross plus
3 nails
----------------
4 given /wwwthreads_images/icons/wink.gif
If only I wheeled as much as Im on this board/wwwthreads_images/icons/crazy.gif

 

Hey scram, sorry to answer so late but I was working a double shift and wasn't home for 24 hours.

From my experience with my NP 207, I cannot get it to shift into 4wd low the way they tell you in the owner's manual. I have to shift into 4wd high then give the Jeep time to get into 4wd high, making sure that the transfer case and the front axle have shifted; the 4wd dash light comes on. At this point the OM says that you can shift into 4wd low while moving slowly in gear (2 to 3 MPH). I've never been able to get into low range like that, even when the Cherokee was brand spanking new. Every time I tried it, it would grind. So what I do is: shift into 4wd hi, then stop and shift the transmission into neutral, keeping my foot on the brake (my XJ has a TF 904 3 speed auto), then shift the t'case into low. After that I've always gotten into 4wd low.

Your NP 242 might have to be shifted into part time 4wd hi first before you try to shift it into low. It seems reasonable that the easiest mode for the t'case to shift into from 2wd would be full time 4wd hi.

You can use 4wd full time off road without damaging it, unlike using a part time 4wd on dry pavement. In off road situations part time 4wd, especially with a locker in the rear axle, would be much less likely to get stuck and would be able to dig itself out should it get stuck. For this reason, the part time modes are a much better choice. That way, you are certain to get 50% of the available torque to your locked axle. In full time, if a tire on the front axle is spinning, then the front axle will get all the torque and you'll spin your fronts and the locked rear will just sit there, useless. Remember that in full time, the 242 transfer case open differential acts just like one in an open axle. In part time, your 242 locks the front and rear driveshafts together, just like a locker locks the two axle shafts together.

Let me tell you a story. About 3 years ago during a snow storm, I came upon a woman and her son trying to get a beautiful 1998 Jeep Grand Cherokee with Select Trac (NP 242) out of a paralell parking spot. The woman was behind the wheel gunning the engine and the kid was out of the Jeep by the rear axle, throwing salt under the rear tires. The rear tires were spinning and whinning big time. I couldn't stand seeing a Jeep abused like that. So I stopped the woman from spinning her wheels and asked, "Are you in 4wd?". To this she replied yes and pointed to the t'case shifter. The Grand was in full time 4wd high. I told her to shift it into 4wd part time hi and slowly pull out. Well, they couldn't believe their eyes, the Jeep came alive and walked right out of that spot. After she got out of the spot , she thanked me. I told her to shift it back into full time. The reason is that Grand's rear tires did not have traction. The open diff in the 242 naturally sent all the power to the slipping rears. When she shifted into part time, now the fronts, which had grip, were getting half the power and were able to pull the Grand out until the rears could find traction of their own. Now, while out on the highway, let's say you ran into a black ice patch. In part time 4wd, both front and rear axles are locked together. If all the wheels lose traction suddenly, the part time system sends power equally to each spinning axle. The gyroscopic effect of the spinning tires cause the Jeep to go sideways without steering control, a pretty dangerous situation. In full time 4wd, you won't get the gyroscopic effect.

I hope this long winded reply helps. /wwwthreads_images/icons/smile.gif

 

That was the answer i was looking for man ty. I didnt know all that before. I was a;ways unsure which is bettter to use offroad and it seemed at times one mode would work better than the other. And stupid me thought that full time sounded better so i used that whenever possible. But ty now i know the difference. In my old scrambler and yota all i had to do was just shift her into 4l and drive her. I was stupid with the cherokee and would use 4h full time even when low range would be the best because i thought that well if it says part time it ment it would only work half as good. THANX MAN SCRAM

The moment you are born you start to die so buy A Jeep and play hard!!!!!

It's All Out or Nothing At All!!!!!!!