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MJ Conversion to 4x4?

A

azwnbfpro

NAXJA Forum User
Location
Arizona
How difficult is it to convert a 2wd MJ Comanche to a 4wd? Anyone here ever done this? I found a clean MJ for sale cheap, but it's 4x2 and I would want it to be 4x4. Is this worth doing? Too costly?
 
I've done this swap and it is relatively straightforward if you're mechanically inclined and can source good parts for cheap. You'll need a new transmission/transfer case, front axle, front driveshaft, rear driveshaft and all the bracketry for the transfer case linkage. You will also have to cut and splice extensions into your speed sending unit wires for them to reach their new plug at the rear of the transfer case. All that said, if you don't already own the 2wd Comanche pass on it until a 4wd comes up. If you do already own the 2wd Comanche it's easier and often cheaper to sell it and go find a 4wd one to buy.
 
i'd do it in a heartbeat. it's all bolt-in, and an mj of any kind is tough to find, but you can use dime-a-dozen xj stuff for the swap. DO IT! :viking:
 
Hellbent said:
i'd do it in a heartbeat. it's all bolt-in, and an mj of any kind is tough to find, but you can use dime-a-dozen xj stuff for the swap. DO IT! :viking:
Click to expand...
This is also a valid point. Now that I think about it, it's been a hell of a long time since I've seen a 4wd 'manche worth buying (at a reasonable price anyways).
 
soopergoober said:
This is also a valid point. Now that I think about it, it's been a hell of a long time since I've seen a 4wd 'manche worth buying (at a reasonable price anyways).
Click to expand...

True. There's a guy here in AZ that has a nice 4wd for sale, but is asking $8000.00! That's a little steep for me.
 
If it is overall in at least decent shape pick it up.
 
I'm on Comanche number 3.

I have an 88, had an 89, and just got a '91. All left the factory 2WD and I am now picking up the parts to convert my 3rd one.

I actually prefer the 2WD ones as prices are more reasonable, and it is a safer bet they haven't been beat on.

Converting is pretty easy. I don't know about a one-day job, but it is doable in a weekend. Don't forget the interior has to come out to drill the holes/bolt in the body side bracket for the T-case shift lever.

So, axle swap, brake bleed, trans/t-case swap (or main shaft replacement in the trans) bleed clutch (or do trans fluid flush), remove and reinstall seats/console/carpet. Hope for no rust in floor, or do that while you are there. Cut hole for shifter, drill 4 holes to bolt it up, install new driveshafts.

The PITA for me is always finding an MJ rear D-shaft that is really the only MJ-specific thing you need, all else can easily come from an XJ. I had a new shaft made last time, and I'm going to see about just shortening this one this time.
 
I'm halfway through doing this right now, putting the new front axle in was an evening worth of work (actually split over two days, but that's because I had to stop making noise at 9pm or the neighbors/landlord would get angry) and I expect the transmission/transfer case to be about the same. The rear driveshaft is really the only thing you will have trouble finding and you can get your stock one cut down and rebalanced by a shop for about 100 bucks probably.

What year is the one you're looking at? If it's 90 or earlier you'll need to buy a longer speedo drive cable setup, they don't cost much it's just a pain. If it's 91 or 92 it'll be electrical drive and you can just splice the wiring.

EDIT: I posted the OEM part numbers for the speedo cables here if you need them - http://www.naxja.org/forum/showthread.php?t=1011475&page=2#24
 
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Hm, I thought my '91 had a speedo cable and electric hookup on the transmission.

No biggie, can find an XJ with the right parts, but just saying.

Kastein- you all done with the rust fighting?
 
Not yet... doubt I ever will be :roflmao:

I've still got rust on the gas tank, one frame rail, some floors, the bed sides, and a bit starting on the roof that I need to rattle can till I can devote a few weeks to painting it properly. I've been daily driving it because my XJ is down with a nearly blown transmission, so I have been careful about how long I leave the MJ undriveable. As soon as I have the brakes 100% fixed on the MJ, the XJ is getting the new transmission so I can stop worrying about being one vehicle away from immobile.
 
Wow, thanks for all the useful info! I thought of another question, the 2wd I'm looking at has a lift on it. Will the lift on a 2wd work on a 4wd? Or will it need a new front suspension?

It a 1989 by the way.
 
azwnbfpro said:
Wow, thanks for all the useful info! I thought of another question, the 2wd I'm looking at has a lift on it. Will the lift on a 2wd work on a 4wd? Or will it need a new front suspension?

It a 1989 by the way.
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The lift should work just fine. The 2wd beam axles and the dana 30 have the same mounting and suspension architecture. Depending on the lift height you may need/want to consider a slip yoke eliminator on the transfer case and a cv driveshaft.
 
X2 - with the addition that on an MJ the rear driveshaft is a *lot* longer, so I would bet on not needing an SYE till you're talking about nosebleed show truck lifts.

BTW, you can use a transmission/transfer case pair out of any MJ/XJ donor all the way up to 1997 with some minor wiring harness splicing, perhaps slip yoke swapping, and sensor swapping - I would stick to 95 and earlier however to keep the slip yoke design the same.
 
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