MVDCXJ

84Supersport, some XJ's have a 4wd full time selection on the lever because they came with the 242 transfer case. Mine is like yours and has the 231 t-case which only has 2wd-4wd-N-4wd low on it.

84supersport

OK, so the full-time 4wd selector, if it had it, would pretty much be like having an awd vehicle.

MVDCXJ

Yeah similar. It allows for some slipping so it can be used on dry roads as well.

BillyBoy

Hey man, certain years (older) cherokees have only the 3 options:
2WD 4HI 4LO.

Newer ones say 2WD 4Parttime 4 Fulltime 4Low

From what I gather,
the 4LO is for really deep doo-doo, (or pulling a boat out of the water...)
the 4 HI (on the older models) is for general offroading/slippery stuff.
2WD... self-explanatory.

On the newer ones with the 'parttime' or 'fulltime' option, there seems to be differing viewpoints on what they do/when to use them. I've been reading alot of threads on it and it seems the general consensus is that in "part time" the front and rear axels are locked at the same rate of speed. Supposedly not good when turning or for longer drives on pavement.
The "fulltime " option seems can be used "full time" with only a hit to the gas mileage as a deterrent.

Really, If you only have 4 HI and 4 LO, the decision is made for you. Only go into the LO if you're REAALLLLLYYYY worried about getting stuck.

The only thing I might worry about is that when using 4HI you might have the locked axels... with the same spin. Might be worth some more research, especially if you are worried about buring up your t-case (transfer case) on the highway.

Then again, there's always the owner's manual.

If it's "new-to-you" (used) you might want to change the t-case fluid... there are a few good threads about how on this site. I did mine when i got it and what came out looked like mud...

Good luck- this Jeep stuff is addictive.

PostScript:
If anyone has any corrections for my post, please do-
I'm always looking to learn.

rivercrazy

I agree with pretty much all that ^^^^. The only thing I would say is 4L isn't ONLY for deep doo-doo or really woried about getting stuck. 4L almost triples the gear ratio to the rear axle which puts a lot less strain on your drive train, so I say it should be used for most general offroading at low speeds.

Unless you're just cruising down a dirt road (or you have more ***** than brains and you think your XJ is a pre-runner) 4L is what you want to be in for rock crawling, hill climbs, hill descents, tearing up your a-hole neighbor's lawn, driving over your ex's car, etc.

Have fun!!

double_ot_xj

I have a 231 and I use 4 high on snowy roads and out in the boonies. Like when I was down the canal 4 high. I couldnt tell you anythin about the 242 but im sure its similar. Hey delco, hows that new bumper?

DELCOZRT

I'm loving it! Thanx again for all your help.

GoreXJ95

So basically my 231 when it says part time is really all wheels are locked in an turning? Correct me if im wrong. Also JUST WONDERING, what is better the NP 231 or NP 242.

offroadnut36

I only ever use full-time on roads no matter what. I never use part-time on roads unless they are COMPLETELY covered with snow.

Full-Time is differentiating, like an open rear end.
In Part-Time both front and rear driveshafts are locked. think about turning withe a spool in the rear end, only if the stress is too great you'll split oen your t-case.

offroadnut36

First part, yes you are correct.
Second part, It really just depends on how you drive and where.

GoreXJ95

Ok thanks, also you can shift into 4wd on the fly but how safe is it for your gears. When i shift into mine when i get to 30 to 35mph i hear a low grinding sound like its working overtime.

offroadnut36

I usually dont shift on the fly with mine. With mine it usually doesnt shift from 2wd to full-time unless I'm going below 20 mph. So I just wait till I hit lower than 20 mph or a stop sign/redlight. Yours is newer though, so I am not sure. You can't shift into 4hi above 45 mph though. If it starts grinding just slow down a little and try it again.

GoreXJ95

Yea well is it a pre sign that something could go wrong.

offroadnut36

No, it just means the gears are spinning too fast to mesh with eachother, so they end up grinding against eachother. Now if you keep grinding them they will go bad after a while.

duncan0668

Logic would be full time 4wd would be FULL Time.
Part time 4wd would mean PART Time.
But as my 01 Grand Cherokee had both and I used them as logic would dictate. I guess I was lucky I never drove in 4WD on a dry road.
When I bought my 99 Sport I thought I was screwed with only part time 4WD but since then I have read the owners manual and learned the correct Jeep discription of Full and Part time 4WD.