Converting a 2wd MJ to 4wd...

[Chili Palmer]

I recently picked up a 4wd 84 XJ and a 2wd 88 MJ. I was poking around a little bit and it appears that it's fairly simple to convert the MJ to 4wd.

A few specs...

84 XJ
2.8 V6 that runs but does spit a little oil out the tail pipe - doesn't burn it so I think its the valve seals - I'll be looking into that.
AX-5 tranny - seems to work pretty good at this point
NP207 - it works also
D30/D35 Combo (not sure on the gears - I haven't got that far yet, I just picked them up today)

As far as the body goes it's fairly straight. It was a farm truck and the guy I bought it from gutted it (completely) because he was going to have it Rhino lined but then he sold the farm. Basically it has two front seats, the back seat and a steering wheel - no dash - no plastics anywhere. The only glass it has is a cracked windshield (which allowed me to show my son how windshields are made!). There are no doors (it's a 2 door by the way) and there is no lift gate. It is also missing all the lights, the grill and a few more odds and ends - as I said - there are two seats and a steering wheel - which is all I need! My plans are to set this up for trails that I'm not willing to take my '05 TJ on (bought it new and it only has 6000 miles right now). I'm in no hurry to get it done because I do wheel with my TJ fairly regular.

The MJ on the other hand is 2wd and does not run but it has the 2.5L (which is not original because it had the 4.0L sticker on the tailgate - not really sure how that all came about but I'm going to try talking to the guy I bought it from). It also has a 4spd (not sure if it's the AX-4 or the T-4, haven't got that far yet.) And of course it has the good 'ol D35 out back.
Overall it's in pretty good shape (much better then the XJ).

So I go pick it up (ended up paying $80!) and bring it home and the wife says "Well that's a cute little truck" - at which point I say to my self "there goes my parts truck!"

So now my wife wants to me to get the MJ running for my son - who can drive in about 6 months - he wants a 4wd but he really likes the truck. So I'm thinking about swapping everything (motor, tranny, TC, front axle, etc. - this way I can basically have a fresh start with the XJ) over to the MJ (including the front clip so I can have the different radiator support in my XJ for future use!) so he has 4wd. I figure if I do this my wife will probably be a little more relaxed when it comes to mods on my TJ and XJ.

So after all that rambling - how hard is it to convert a 2wd MJ to 4wd.

Also, do I need to swap the hole clip over to get the different radiator support? From what I can tell, I'll need to swap the hood (because they latch differently - the 84 latches in the middle on the support while the 88 has the latches on the hood in the corners), fenders, front radiator/grill support (the front piece of sheet metal).

Any help would be appreciated, thanks.

P.s. - Sorry for the long post...

 

[RichP]

More than likely the tail gate was replaced vs the drive train. The conversion is pretty straight forward especially if you have the donor vehicle side by side on a hard surface. There are also some other options, how deep are your pockets
The front axle just swaps over, thats the big part. the only issues I have run into transfer case wise is between wrangler TC's and XJ TC's, the wranglers are clocked different and the TC sits up highers requireing a BFH applied from the bottom side of the floor.

The 88MJ will take a 4.0 the other one, the XJ with the 2.8 will not, it won't fit, firewall issues.

 

[Chili Palmer]

Ok, thanks, and I'm aware of the firewall issues with the XJ, thanks though.

Anyone know if the 2.8L has the same bolt pattern as the 2.5L? I'm pretty sure it doesn't, just checking.

 

[74charger]

now is the time to put coil spring spacers on. the axle swap took a friend and myself two half saturdays and a half sunday, and I didn't really know what I was doing. but a coil spring compresser would have helped when we put the 2" spacers on. Good luck.

 

[Chili Palmer]

now is the time to put coil spring spacers on. the axle swap took a friend and myself two half saturdays and a half sunday, and I didn't really know what I was doing. but a coil spring compresser would have helped when we put the 2" spacers on. Good luck.

That part should go fairly well as I've done one D30 swap already and a couple of D44 swaps. As far as the spacers go, we just jack up the opposite side of the axle and have someone step on the other end (the end we're putting the spacer in) and put the spacers in, works like a charm.

Today we got the tranny out of the MJ (I'm putting the 5spd from the XJ into the MJ) and started on removing the TC and tranny from the XJ. I just only need to remove the two bolts on top of the bell housing, the crossmember and then unplug the electrical connectors and we should be good.

Question: I'm also going to swap rear axles because the original MJ axle is leaking where the tubes go into the housing (common D35 issue) but the XJ is not. The problem is the MJ is spring under while the XJ is spring over. What is needed here? Cut the spring pads off each and swap them (which will require me to purchase a welder but that's cool, I've been wanting one and this would give me an excuse!)? I also noticed the shocks are mounted differently, are the shocks the same or is that going to be a problem (I'm assuming I will use the shocks from the MJ as they are definitely the right length.).

One more thing, anyone know a good place to get a reman'd 2.5L? I know it's not the best choice in the world but it's what the MJ came with and I'm doing this on a major budget so I don't want to start swapping wiring and all that other crap, besides, my teenager is going to drive it and he doesn't need any more power then that when he begins driving.

I'm trying to keep the whole project under $1000 (not including the engine stuff) for everything. Which shouldn't be too hard because as of right now I have a total of $180 in to both vehicles so if I have to spend a little money on the engine that's fine.

 

[lawsoncl]

I think the 2.8l and the 2.5l have the same GM60 bellhousing pattern. On the rear axle, you are correct that you'll need to cut and reweld the spring perches and shock mounts. You have to do this even if you want to convert to spring over on the MJ as the spring perches are spaced differently.

For a cheap lift, going spring over in the rear gives you about 5.5" over stock. Figuring the stock springs have sagged a bit means you can pair that with a set of 4.5" springs for the front. If you go spring over, moving the rear shock mounts to the center of the axle (up-down that is) works well for using stock XJ 4.5" lift shocks and gets them up out of harms way. Essentially, you need a 4.5" XJ lift kit without the rear springs (or add-a-leaf). I did this on my 89 using for about $350 and ended up about 5" over stock front and back and I comfortably run 32s.

 

[Chili Palmer]

I think the 2.8l and the 2.5l have the same GM60 bellhousing pattern. On the rear axle, you are correct that you'll need to cut and reweld the spring perches and shock mounts. You have to do this even if you want to convert to spring over on the MJ as the spring perches are spaced differently.

For a cheap lift, going spring over in the rear gives you about 5.5" over stock. Figuring the stock springs have sagged a bit means you can pair that with a set of 4.5" springs for the front. If you go spring over, moving the rear shock mounts to the center of the axle (up-down that is) works well for using stock XJ 4.5" lift shocks and gets them up out of harms way. Essentially, you need a 4.5" XJ lift kit without the rear springs (or add-a-leaf). I did this on my 89 using for about $350 and ended up about 5" over stock front and back and I comfortably run 32s.

Thanks for the info and that's something I might look into, the spring over that is.