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Where is my Full Time 4H?

B

BogdanR

NAXJA Forum User
Location
San Diego
Hi guys,

I was a short time 89 XJ Limited owner. Got one for $750, but sold recently because it was just using apart. Ever since I upgraded to a 96 XJ 4x4 with 5 speed.

On my 89 I had a 2H, 4H Part Time, 4H Full Time, and 4L. On the 96 I don't seam to have 4H Full time. What does that mean? Actually, can any one run down the difference between those options. Part time vs. Full time.

Also, when driving in 4H Part Time in the new XJ on pavement, it feels like it's pushing quite a bit. I only drove for a few blocks. On dirt it's perfect. Any idea why? I am used to Range Rovers, which are 4x4 all the time, so not sure if jeep's are not supposed to be driven 4x4 on pavement.

Thank you,

- Bogdan
 
Re: Wear is my Full Time 4H?

Yeah the newer cherokee only has 4H and 4L part time. They say to only use it on slippery surfaces, so unless it's really wet out or snowing you should not use it on road.
 
Re: Wear is my Full Time 4H?

So, basically, it's just a 50/50 split in part time, front and rear are locked? That's what I am getting from the forms. While full time has a center diff? That's poor naming if i ever saw one. :)

Does the full time transfer case uses a real diff or a clutch and wheel speed setup?

- Bogdan
 
Re: Wear is my Full Time 4H?

the NP242 is what you had, it has an open differential between the front and rear outputs in fulltime mode. The NP231 (what you have now) locks the front and rear driveshafts together in 4Hi, which is like the 4wd part-time setting on the NP242.

You can easily pick up an NP242 for yours, it's really a matter of personal taste. Many more aftermarket upgrades are available for the NP231 so a lot of people favor it.
 
Re: Wear is my Full Time 4H?

Naming is a little screwy, but the way I used to remember it was that Part-Time can only be used part of the time, Full-Time can be used full time (all of the time).
 
Re: Wear is my Full Time 4H?

The 242 was only offered with the AW4 in the XJ. The manuals all got the 231.
Otherstatements above are correct.
 
Re: Wear is my Full Time 4H?

BogdanR said:
So, basically, it's just a 50/50 split in part time, front and rear are locked? That's what I am getting from the forms. While full time has a center diff? That's poor naming if i ever saw one. :)

Does the full time transfer case uses a real diff or a clutch and wheel speed setup?

- Bogdan
Click to expand...

I agree that the naming is stupid. They should really use something more clear like "offroad 4wd" and "street 4wd.

I only realized how stupid the terminology is when I got in my friend's Jeep Liberty. I noticed that her selector was on PART TIME and she said that's where she always keeps it!! She thought that part time meant it would be 4WD only part of the time when it's needed, and that full time means it's always 4WD.
 
Re: Wear is my Full Time 4H?

BogdanR said:
So, basically, it's just a 50/50 split in part time, front and rear are locked? That's what I am getting from the forms. While full time has a center diff? That's poor naming if i ever saw one. :)

Does the full time transfer case uses a real diff or a clutch and wheel speed setup?

- Bogdan
Click to expand...
That is correct. With the setup you now have, the two axles are simply locked together.

The full time TC in the Cherokee used a plain open differential.
 
Re: Wear is my Full Time 4H?

keep0njeepin0n said:
I have the factory 231 T-case and I have open diffs! You guys are confusing the terminology.
Click to expand...


I believe the open diff inthe ststement refered to the center diff i.e the diff in the transfer case.

With the NP242 in full time uses an open diff in the transfer case thus allowing different drive shaft speeds. The NP231 however have a locked diff (in the transfer case) therefore both front and rear drive shaft spins at the same speed. :idea:Think about a spool in the NP231. Bad for hard surfaces like highway (paved road) driving and parking lots except of course if there is snow and/or ice on the road.
 
Re: Wear is my Full Time 4H?

keep0njeepin0n said:
I have the factory 231 T-case and I have open diffs! You guys are confusing the terminology.
Click to expand...
ummmm, nope.

The transfer case has another diff in it in the 242, which is open. That's what he was referring to.
 
Re: Wear is my Full Time 4H?

keep0njeepin0n said:
I have the factory 231 T-case and I have open diffs! You guys are confusing the terminology.
Click to expand...

You're referring to the differentials in each axle, not the transfer case.
 
Re: Wear is my Full Time 4H?

kastein said:
the NP242 is what you had, it has an open differential between the front and rear outputs in fulltime mode. The NP231 (what you have now) locks the front and rear driveshafts together in 4Hi, which is like the 4wd part-time setting on the NP242.

You can easily pick up an NP242 for yours, it's really a matter of personal taste. Many more aftermarket upgrades are available for the NP231 so a lot of people favor it.
Click to expand...

What he said!! :peace:
 
Re: Wear is my Full Time 4H?

I guess I always thought the names "part-time" and "full-time" made sense. I don't know that I miss the full-time either. (went from 87 242 to a 96 231) If where I'm driving is bad enough to need 4wd, then full-time works just fine. Otherwise, 4wd is just a waste of gas IMO. Although, for people that don't want to be switching back and forth or don't really know when to, full-time may be helpful.

Is there any difference in strength or weight between the two? I thought I remembered hearing the 231 was stronger, but that hasn't been mentioned in this thread yet.
 
Re: Wear is my Full Time 4H?

Thanks for clearing everything up. It seams to me that 231 would be stronger at least in theory. You know, less parts means less things to brake. On the other hand, having a differential in the middle is kind of nice for rain conditions. It does not get much worse then that here in San Diego, so I don't really need the full time 4x4.

Thank you for the help,

- Bogdan
 
Re: Wear is my Full Time 4H?

Part time 4x4 really shines when you drive on roads that vary from bare pavement (wet or not) to slush to snow and ice frequently. That way you have the benefit of 4x4 but don't have to keep turning it on and off as you come to slippery sections of road. Other than that, I don't really see much use for it - I actually prefer part-time on the snow because it forces at least two wheels to be turning (even with open diffs front and rear), while the open diff in a 242 transfer case (when combined with open diffs front and rear) effectively turns into "1 wheel drive", at least theoretically.

A 242 with limited slip in the rear and a selectable or auto locker in the front would be pretty nice though.
 
Re: Wear is my Full Time 4H?

kastein said:
Part time 4x4 really shines when you drive on roads that vary from bare pavement (wet or not) to slush to snow and ice frequently. That way you have the benefit of 4x4 but don't have to keep turning it on and off as you come to slippery sections of road.
Click to expand...

I think you mean "Full time" not "part time"

kastein said:
A 242 with limited slip in the rear and a selectable or auto locker in the front would be pretty nice though.
Click to expand...

I love my 242TC with Detroit locker in the rear and ARB in the front. Great setup.
 
You are correct, I misspoke :dunce:
 
I see the "full-time" / "part-time" terminology rise way too frequently here. Doesn't anybody have/still have their owners manual, or that sticker on the drivers side visor? Both explain when to use/not use 4-wheel drive selections.

Or, maybe folks don't bother to read those things any more?
 
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