Hey guys - I did look into the solid axle swap in great detail a while back. Here's a writup I did that covers most of the issues, though more would likely be discovered during the process.

I keep seeing offhand comments about a solid axle swap on our rigs and I was seriously considering it a few weeks back, if for nothing more than to be the first (that I know of). Liberty guys do it all the time, but I haven’t seen an XK with it yet. So I decided to write up what I’ve researched about this mod.

My goals – it would have to still be a decent daily driver and it would have to off-road better than it does now (otherwise, what’s the point?). By the time I finished looking into it, I wasn’t convinced either goal could be met without more trial and error than I was willing to endure, much less the open-ended financial aspect of something like this. And once started, there would be no turning back without great cost as well. Bottom line for me – I couldn’t experiment to this degree on a three year old, 35K rig that I depend on every day.

I went through the front end with a local fabricator, Mike at RMB 4x4 (rmb4x4.com) who’s done many SFA swaps on 4-runners and such. He was eager to do one on the Commander and the consensus is yes, it could be done pretty easily. I estimate about 7K to 8K to do the job, more if you swap out the rear axle to a JK spec D44 with electric locker and/or additional fabrication to lift the rear to match the front – more on that later.

I’m speaking from the point of view of a Quadradrive II guy. I apologize for not knowing more about the other available systems, but I will say - my suggestion to anyone serious about this, and I suspect that will be very few people – start with a non-QDII Commander. I was not interested in ditching what I consider a great rear axle for a JK rear axle. A lot of guys who build really big JK’s start with an X model since they’re going to ditch the axles anyway. That being said, I don’t know how the electronics will fare by removing only the front ELSD unit. (My assumption is the new JK front axle locker would be activated by a toggle switch as it is an on/off type unit as opposed to the ELSD which is variable from open to “lock”.) The electronics are a big question. ABS shouldn’t be a problem and ESP can be turned off. But there’s a lot more there working together than just those two systems. With QDII, the traction control would not know what to do without the ELSD front axle as would the stability program if you attempted to make it function. Maybe these systems could be made to work somehow, but someone smarter than me would have to figure it out. Otherwise, it appeared I might live with some of the systems non-functional and warning lights on the dash glaring at me.

I would start with a JK spec front Dana 44 with the electric locker. That would run around 3K give or take from Mopar. Problem with that right off the bat – it’s a 4.11 ratio. So if you choose to keep your current gear ratio (Commanders don’t come with better than 3.73 and I think that’s only in the QDII rigs), you’re already swapping new gears into the new front axle. And to go from 4.11’s to something worse like 3.73’s just hurts! Otherwise, if you can swap the gears in the rear to 4.11’s, you’re better off. But again, QDII guys (at least) can’t do that as aftermarket gear sets are not made for the ELSD rear axle. So there’s the motivation to put in a new JK rear axle, and another $2,500 bucks. But at least you then get the 4.11’s.

Everything having to do with the IFS comes off. Steering rack, knuckles, struts/coils, upper and lower control arms, bracketry/tabs to mount all that, etc. Some of it gets torched off, thus the “point of no return” I referred to. This isn’t something that can be reasonably undone. A Saginaw-type steering box would have to be mounted and with some reinforcement didn’t look like a big issue. This would have to be carefully done, however, as the unibody doesn’t lend itself to the stresses the box would see since it wasn’t engineered for it in the first place (like a ZJ or WJ). Especially since presumably, one would be turning 33’s or larger tires. It shouldn’t be too tough to modify the steering shaft (from steering wheel to steering box).

The factory strut towers are a good starting place to mount the new coils. The inner fender/fenderwell area would essentially be rebuilt using steel plate to reconstruct the basic shape of the inner fender. This would spread the load a little more than the OEM setup in anticipation of the larger stresses the unibody would see over time. Take a look at the WJ Mike built in the “complete builds” section of his site. It’s the ’01 Grand Cherokee with the flames down the side. He strengthened the front suspension mounting areas to handle the duty of a Dana 60 front end on that thing. The Commander build would be quite similar. The new axle will require a track bar (panhard rod) to control axle lateral movement. We thought extending the steel reinforcing down a bit might provide a way to mount the track bar to the chassis. This is another area where strength is important – track bars can’t come loose. For the control arms, my thought was the forked Rubicon Express long-arm parts for a 4.5” lifted JK. There is one point of attachment to the chassis and it makes install much simpler. We looked at modifying a cross member made for an XJ long arm lift which could be reliably welded to the Commander and is quite stout. This would provide a good mount for the front control arms. If the factory cross member is kept, it would have to be modified to allow further droop of the new front driveshaft.

Another unknown – how much further would we have to lift the commander in order to provide some up-travel for the solid axle without getting into the bottom of the motor? It appears (by drawing an imaginary line through the center of my front wheels), I’d have to go up 2 or 3 more inches at least (in addition to my 4” kit) to give the front axle some reasonable room to move. I came to the conclusion I’d have about 6 to 8 inches of lift over stock. Depending on bumpstop location (to limit wheel stuffing), you can run 35’s without too much trouble I think.

This would mean lifting the rear even more. While you could squeeze 6” of lift with stock control arm locations and aftermarket control arms, 8” with the factory control arm locations isn’t realistic, another can of worms must be opened. I didn’t consider this in the cost because it was too much of an unknown at the time, but figure another grand or two in modifying the rear end from a 5-link to a 3, as there’s no reasonable way to modify the upper control arm locations at the chassis. Again, I’d go with the Rubicon Express forked control arms to a new cross member, etc. Rear coil and shock absorber locations could probably remain unmodified and an adjustable track bar could be easily adapted to work with that amount of lift.

As for modified or custom parts (or parts sourced from other applications) – Steering shaft, draglink, track bar(s), control arms, coils, shocks, driveshafts, brake lines, ABS/wheel sensor wiring extensions, cross members, gearset(s), assorted bolts/nuts and probably stuff I haven’t even thought of yet. RMB does exceptional work and Mike was looking at about two weeks once he had everything he needed.

Maybe one can see how the “daily driver” appeal is fading?

I’m sure there are plenty of details that I haven’t even considered yet, but this would be a big project for a primary vehicle. Feel free to mention other aspects I may have left out, but I think I got the general scope. I’m sure someone will eventually try this, but I’ve decided I like my XK enough as it is to not potentially turn it into something I can’t stand to drive. Thoughts?