XJ - TJ interchange?

[WrenchMonkey]

Just how similar are the fronts of our beloved XJ to the much maligned TJ?

I guess the motor mounts and exhaust are different, yes?

I've heard the engine sits differently, relative to the axle, so the oil pan is different. Anyone confirm?

What about steering and suspension? Gearbox, control arms and mounts, etc?


Why I ask: my 23 year old unibody has about had it. Instead of building a frame from scratch, I'm considering relocating my oh-so-functional engine, tranny, axles, suspension, steering, etc to a TJ/LJ frame, and building from there.

I know it's doable, anything is doable, but how easy will it or won't it be?

(Mods, move me to OEM or mod tech if that's better, thanks!)

Robert

 

[Ben824]

-The front axle should swap in fine on a lifted TJ/LJ and the front suspension is nearly identical but the rated lift height of your XJ coils should net you an extra inch on a TJ/LJ as I believe stock non-Rubicons coils are an inch shorter. But if you do not want to lift the TJ/LJ and want to leave it at stock height be mindful swapping in the front axle as XJs before 2000 had a High Pinion Dana 30 and all TJ/LJs came with a Low Pinion Dana 30 so you may have clearance issues with the pinion yoke and front driveshaft.

-I have been under both TJs and many XJs and never noticed one slight difference between oil pans.

-The AW4 auto tranny was never available in the TJ/LJ but with that being said there are some guys out there who have swapped them in so it is doable but you will have to research how to do it to see what it involves.

-The NP231 transfercase was offered in the TJ/LJ so that will go in no problem.

-The rear suspension on an XJ and the TJ/LJ share nothing in common. The XJ has a leaf spring suspension in the rear while the TJ/LJ has a coil sprung four link with a pan hard bar (track bar). The axle could be used but the leaf spring perches and shock mounts on the XJ axle would need to be cut off and all the TJ/LJ coil spring brackets, shock mounts, and track bar mount would need to be welded on. Keep in mind you may want to retain the rear axle in the TJ/LJ as some TJs came with an optional Dana 44 rear axle and if I am not mistaken all LJs came standard with a the Dana 44 rear axle. The Dana 44 rear axle would be far superior of an axle than the Dana 35 or Chrysler 8.25 that came in the XJ.

-The stock steering may swap over fine as I never noticed a major difference between the two when I was underneath both XJs and TJs.

-The track bar frame mount is pretty different so I don't see that swapping over if you have an upgraded mount or are trying to use the stock XJ one. Depending on the aftermarket track bar you may or may not have that may or may not work on a TJ/LJ just gotta do some research and part number cross referencing.

In the end, can many of your parts swap over? Yes. But if I were you I would just buy another XJ and KNOW that ALL the parts will swap over. Just my .02 cents.

 

[WrenchMonkey]

Thanks man, that sounds like a lot of good news...

I knew the rear axle would be a can of worms, but since my XJ44 is already locked and geared, I'd plan to reuse it. I just have to decide if I'd rather put 4 link brackets on my axle, or leaf spring brackets on the frame...

I'd also really like to reuse my RE trackbar, but you're right, it'll definitely take some figuring to make it work...

Thanks again!

Robert

 

[kastein]

I'd put 4 link brackets on the axle. I think you can even buy premade kits for it, if not, you can always carefully grind them off the original TJ/LJ axle housing or simply make your own.

When you go to buy a body/frame to put this all on, make sure you check the frame for rust with a punch. Areas that rust out include the frame side control arm mounts for the rear axle and the bolts/nutserts where the trans crossmember/belly pan bolts to the frame. A friend of mine's father's TJ just got a full frame replacement because of this.

 

[clean4drxj]

TJ/LJ Tcases are clocked slightly different as compared to an XJ case fwiw..

 

[WrenchMonkey]

I'd put 4 link brackets on the axle...

That was my first thought, but now I'm leaning toward leaves. I've been happy with my coil/leaf combo for years: flexy enough for the trails I run, stable enough to run on the street without a swaybar. I think I'd lose that stability with four coils.

And if I end up back-half'ing a TJ frame (LJ's are rare and dear), leaves would be much easier and allow a lower, flatter cargo floor.

...check the frame for rust, control arm mounts for the rear axle and the bolts/nutserts where the trans crossmember mounts.

Another reason to back-half. Thanks!

TJ/LJ Tcases are clocked slightly different as compared to an XJ case fwiw..

I'm sure I'll have to re-figure the entire trans and t-case mount. The AW4 is longer than any TJ tranny, isn't it?

I appreciate the input guys!

Robert

 

[kastein]

AW4 is (iirc) about an inch and a half longer than an AX15. Not sure if you have an AX15 in the TJ though, some of them came with NV3550s right?

And I have *no* idea how long the chrysler slushbox for a TJ is.

 

[87manche]

the chryco slushbox is short.

the guy on stu offroad stuffed an AW4 in his because the 3 speed auto sucked. He made it fit. I don't thin the t-case clocking will be a big deal.

T-Case page on his swap:
http://stu-offroad.com/engine/aw-4/aw-4-5.htm

They've swapped AW-4's into a bunch of things:
http://stu-offroad.com/engine.asp

I think Ruffstuff makes the link brackets for the rear axle as a kit. Don't quote me on that.