4x4 Systems..

Command-Trac, Selec-Trac or Quadra-Trac..

Best, worst? Which is the one I should lust after or which one to stay away from? Nuances to be aware of?

Thanks!

(I already read through the wiki regarding these 3 and got the basics; looking for input from actual users..)

TA2Jeep said:

Command-Trac, Selec-Trac or Quadra-Trac..

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Quadra-Trac wasn't offered in the XJ, so that one can basically be disregarded.

Best, worst? Which is the one I should lust after or which one to stay away from? Nuances to be aware of?

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From '87 to '01 Command-Trac implies the NP231 transfer case; Selec-Trac implies the NP242 transfer case.

I've had both and prefer the NP242. It adds a centre differential, which gives you the option of an AWD mode that can be used on solid surfaces (e.g., pavement); this is very useful in lousy weather. The NP231 lacks the centre diff, so its 4WD modes are not intended for on-road use.

The NP231 has a slight edge over the NP242 strengthwise, though in practice it's not really enough that it makes much of a difference. Upgrade choices for the 231 are wider than those for the 242 (particularly where SYEs are involved), but that's not to say that the 242 is without options by any means.

If you're looking at '84 to '86 models that implies the NP207 (Command-Trac) or NP228 (Selec-Trac) case IIRC, but I have next to no familiarity with them so will let someone else field that one.

not to hijack... but

on the NP231 lets say that the road is nothing but snow... can I hit the road in 4wd at 35-50mph?

ericfx1984 said:

not to hijack... but

on the NP231 lets say that the road is nothing but snow... can I hit the road in 4wd at 35-50mph?

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that depends on more than the transfer case. Tires? snow depth, kind of snow etc. But the T-case can handle it.

casm said:

Quadra-Trac wasn't offered in the XJ, so that one can basically be disregarded.

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I was also looking at '93 - '95 ZJs..

I can tell you the quadra trc is 4x4 all the time and part time 4lo

ericfx1984 said:

not to hijack... but

on the NP231 lets say that the road is nothing but snow... can I hit the road in 4wd at 35-50mph?

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Quick answer: the NP231 (and 242) can be shifted into and out of 4HI at any highway-legal speed per the owner's manual.

Longer answer: if you're transitioning from loose surfaces (snow) to firm ones (pavement) and/or back again, the lack of a centre diff may put loads onto the driveline that it's not really intended to take; the same applies to steering under lock. Usually this isn't an issue, but can be over time or depending on the circumstances. I'd recommend searching on this as a lot has been written on it over the years and it's somewhat outside the scope of this thread.

TA2Jeep said:

I was also looking at '93 - '95 ZJs..

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You may want to do some reading up over on NAGCA about the NP249. That case isn't really considered to be especially spectacular or much of an upgrade for anything in particular.

I believe all the V8/4wd ZJ's had the 249.. I would stay away from it. If you find one cheap enough.. swap in a 231/242.

I love Selec-Trac. As already said it's great on the road in snow or mixed snow/pavement. Also for driving fast in the rain when in RWD the XJ can be a bit tail-happy.