New MJ owner needs advice for 4x4 swap

[MJ86YJ90]

So i picked up a real clean 2wheel drive 86 comanche. has 2.5 in it I want to do the 4x4 swap since the body and under side are spotless. My question is what kind of a cherokee donor should I be looking for? my comanche now is a 4 speed id like to keep it a stick but a speed would be better. How is this 2.5 in the 4x4? thanks

[Garvin]

It all matters what you plan on doing with it. You can find a '91+ Cherokee to get the 23 spline transfer case and trans out of it, grab the front axle and front driveshaft (front axle is non-disco :thumbsup: ), then you will need to find a Comanche for the rear driveshaft. That trans will set you up with an AX5 5 speed manual, but will need to have a 4cyl engine in it.

 

You will need to find someone parting one out or one in a junkyard that is the same wheelbase (short bed or long bed) and 4x4 to get the rear driveshaft to fit.

[Geonovast]

Even the newer AX-5s don't have 23 spline transfer cases.

 

You can grab an AX-5 from any 2.5 equipped XJ, MJ, YJ, or TJ. YJ and TJ ones may clock the T-case up a bit, but that's not really an issue.

 

Your best bet is to grab an entire 2.5/4wd/5 speed XJ as a donor. This will give you literally everything you need except for a rear driveshaft, and your best option for that is to have yours cut down. Average for that is $60-$110, which you'll probably spend nearly that much on the correct one anyway. Finding a stock driveshaft for what you need will not be easy.

 

Front axle will go directly on. If you pick up a 3.55 geared front to match your current rear, you're set. However, if you get a complete donor XJ (2.5/5 speed should have 4.10 axles), the rear will need the XJ perches cut off and MJ ones welded on. You will be much happier with 4.10s, as 5th with 3.55 axles isn't very useful.

[MJ86YJ90]

great ill be on the lookout for a parts machine but I am guessing an xj with the 2.5 will be hard to find

[Geonovast]

Shouldn't be all that hard, would be if you were looking for one with an auto.

[MJ86YJ90]

what are your thoughts on just doing a 5 speed 4.0 swap?? worth it or not really? i can find 4.0 5 speed xj's all over compared to the 2.5

[Geonovast]

4.0 swaps a lot of work, but pretty straightforward if you get an entire donor XJ. Even if you pick up a 4.0/5 speed XJ, I still recommend at least finding a 3.55 geared front to match your rear. 3.07 gears are crap.

[mjeff87]

4.0 swaps a lot of work, but pretty straightforward if you get an entire donor XJ.

 

agreed....it is alot of work, but it's not alot of technical/fabrication work. Nearly 100% of the parts bolt in, but it's getting all of the little pieces/parts correctly that's a chore. I swapped a 4.0 into mine, but I spent the better part of a year gathering parts a piece at a time as I found them, and then took the better part of two months working on weekends doing the swap (although I did alot more than was absolutely necessary to get it up and running, but I'm a stickler for details like that..... :D )

 

End result is something that I built from ground up and am confident in running, and a happier person for doing so.

 

Jeff

 

edit: welcome to the club, from a 'burgher now transplanted to VA :cheers:

[mvusse]

4.0 swap means replacing the upper and lower radiator supports, possibly massaging the firewall a bit with a hammer (supposedly some late 86s already had the newer firewall to fit a 4.0), fuel pump, and entire engine bay wiring harness. Then in addition to the motor you need to swap the radiator (plus pressure bottle?), air cleaner and possibly accessories like alternator and power steering pump.

 

If you get a 4.0HO, it will also mean the fuel sender, entire dash wiring harness and splicing it into the rear harness somehow. You would be rewiring 3/4 of the entire truck if not more.

[MJ86YJ90]

I have actually been finding a few 2.5 5 speed xj's also a few 5 speed trannys by themelves let the parts gathering begin

[89flat]

i just got done doing this swap as well her is what i ended up using

 

trans out of a 4x4 with the V6 or 2.5 will do

transfer case that i used was a 231 out of an auto matic cherokee as they have the correct spline count

rear driveshaft out of a chevy monza was a perfect fit along with a 7 inch slip yoke from gm

front driveshaft was out of a dodge dakota 4x4 with IFS, also perfect length

t-case linkage i used a factory floor shifter and some mini-heim joints and some all thread

 

good luck it was a challenge and a whole year long proces of finding the correct parts