PT-FT 4x4?

so obviusly im still learning my sweetness! here ya go- from 4H(part time) to 4L(Full Time) should i see a light that tells me when im in PT to FT in my 90 4.0? i have a light for PT, but not FT? be sides what truly is the diff in 4L to 4H be sides crawling and street? do i have my ducks lined up so far on this subject or at least headed in the rite direction, TJ

uhhh, what transfer case do you have? If you have the 231 with 2Hi - 4Hi - N - 4Lo on the shift lever, do NOT use 4Hi on the street unless it is extremely slippery (snow/gravel/whatever, not rain) or you will damage your TC and/or drivelines. Since you only have part-time light, this tells me you have a 231. 4Hi and 4Lo are both part-time on this transfer case, you should only ever use 2Hi on dry roads.

The difference between 4Hi and 4Lo is that 4Lo has an additional 2.72:1 gear reduction for higher torque at the wheels, and 4Lo requires a special shift procedure:

* shift into 4Hi
* shift tranny into N while coasting around 2-3mph
* pull transfer case shift lever to the right and shift cleanly and smoothly, all in one movement, into 4Lo
* shift tranny into drive again

If you do not follow this procedure you WILL grind the gears to some degree.

You have the NP231 T-case. There is no full time option on that transfer case. THere is a light in the cluster but it won't get activated with the 231. When you shift into 4wd the Part time light will come on indicating you are in 4wd. If you had the np242 t-case you would have the full time option when you would shift into 4(all-time) you would also have part time 4wd with that t-case.

i do have the 231 i guess cuz its he set up that ya speak about, yeah i just use 4H when we have snow or ice only, is the 231 a decent tranny? and from what ya say i have NO full time! hmmm so is fulltime when ya have hub lockers? thanks

231 is a decent transfer case, yes. Most people like them more than the 242 for a variety of reasons, I believe the top two are that it's stronger in 4wd (not sure?) and that you can get prebuilt SYE kits for it. The tranny in any automatic XJ (past the early years at least) is actually an AW-4.

The 242 fulltime option I believe uses either an open differential or a viscous clutch between the front and rear drivelines, so that it won't cause binding and damage when you corner with good traction.

kastein said:

231 is a decent transfer case, yes. Most people like them more than the 242 for a variety of reasons, I believe the top two are that it's stronger in 4wd (not sure?) and that you can get prebuilt SYE kits for it. The tranny in any automatic XJ (past the early years at least) is actually an AW-4.

The 242 fulltime option I believe uses either an open differential or a viscous clutch between the front and rear drivelines, so that it won't cause binding and damage when you corner with good traction.

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Yeah, the NP/NV 231 is a good transfer case, it can accept heavier chain and gears, with its main drawback being a thin case so if you like bashing the underside into rocks a good transfer case skid plate is very important. SYE are available for the 231.

The NP/NV 242 will not accept the heavier chain and gears as the internal differential--which permits the FT 4wd--takes up all the space. It too has a thin case, and it is "clocked" differently making it hang a little lower, so a skid plate is important for it too. No SYE available other than a "hack and tap" setup.