New XJ owner question

I have owned 3 Chevy/GMC K5 Blazers, a 1997 Wrangler, currently a 1996 Chevy 2500 4x4 Suburban and now a 1990 XJ, but still I am confused on the transfer case set-up of my new XJ addition. I am use to 2-hi / 4-hi / and 4-low. I am not use to all this part time and full time and having to move the lever up and down 3 different times to get the light on the dash to go out (back to 2-hi). My question is were there any t-case options in 1990 (are all XJ's equipped with the same T-case)? Do all XJ's with this set-up wobble the hell out of the front tires during u-turns or sharp turns? Again, i have always vehicles that had manual locking hubs. What are some basics that I should know about this set-up and what is the weak link in the drive line??
These are newbie questions that will only get asked once by me. I tried to search for past topics, but nothing really answered my questions.
Thanks, Sam

There are two basic tranfers, the NP 231 (commonly called the part time) and the NP242 (commonly called the part time).
The NP231 2X, 4X high and 4X low. Locks the front diff with the rear diff. in the 4X mode. Normally only used off road or on snow covered streets. With the narrow wheel base and the steering geometry, using the 4X mode on pavement or even rain covered pavement, makes the Jeep feel like your climbing a curb when turning a corner. The drivetrain loads up. Possible damge to the drivetrain on dry pavement. I´ve got a Chev, with the 241 transfer, pretty much the same as the 231, the climbing action on corners isn´t as noticeable as the Jeep, but you can still feel the drivetrain load up on dry pavement.
The NP242 has the 2X, 4X part time (high and low) (same as the 4X and 4X low in the 231) and 4X full time, which has an extra clutch in the transfer to help the drivetrain unload when turning, on dry, rain covered or pavement with patchy snow. Makes the pavement use of 4X much more seamless, but you do loose some overall traction capabilities.
The transfer seems to shift better, the more you use it, shifting out of 4X can be problematic. There are various techniques that work, stoping and shifting to nuetral or even reverse. I sometimes have to back up a bit. Have been experimenting with shifting out of 4X just as I come to a full stop, which has been working well for me so far. Shifting into 4X is pretty much, at any realistic speed (below 45), I sometimes have to back of the gas a touch to help with the shift.

I'm funny about shifting between 2x and 4x. :jester: I always stop, put it in N, and then shift. Call me crazy but it just seems like it may be a little easier on everything. I never use 4x on anything but dirt, sand, or mud but then I live in FL and it doesn't snow here...

Sam, sounds like you have the 241Tcase. That is commonly called a full time tcase. Check your front axle for a disconnect vacume motor. I do not think the 241 had that in 90. I have an 84 my self. If you have any of the IM services feel free to IM me with any questions. You can get the info from my post. As for the weak link. I'd say the rear axle assumeing you ahve the D30.

rear = D35... front = D30... :laugh:

Hawaiian Style said:

rear = D35... front = D30... :laugh:

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Opps! And I just put a lock-right in my D30 :anon:

8Mud said:

using the 4X mode on pavement or even rain covered pavement, makes the Jeep feel like your climbing a curb when turning a corner. The drivetrain loads up.

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Thanks for the assistance, but that is what worries me. I am in 2-hi when my tires start freaking out during a turn. Just to make sure I wasn't driving around in 4X I jacked up the jeep on a lift put it in gear and only the rear driveshaft turned, But if I manually turn the front wheels it turns the front driveshaft. Is this what you mean by a full time T-Case. Is it normal to make a U-turn and feel like the front tires are going to fall off in 2-HI. It is similar to being in 4X on dry pavement.
Sam

With the tranfer in 2X, the transfer to the front wheels is in neutral, turning the tire with it off the ground, will turn the driveshaft or the other tire in the opposite direction in an open differential, both tires in the same direction if there is some kind of traction aid in the front diff.
At full lock, due to the steering geometry you can drag a tire a little. Gets worse if the alignment is out. If your sure your front diff is disconnecting, it´s either normal or alignment. I notice mine drags a tire a bit at full turn, usually notice it most with one tire on a slick surface, like a man hole cover. Not nearly as bad in 2X as in 4X, in 4X part time it really feels like it´s trying to climb something. But haven´t noticed any strange tire wear.

A dry front axle shaft U joint will make the front shimmy a little at or near full lock. It will eventually make a clack clack clack sound when turning sharply, you can feel it in the steering wheel.