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2wd to 4wd swap


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Like to start off by saying hi, first time here, just picked up an 89 Comanche yesterday. These things are incredibly rare where I'm from (New Brunswick, Canada) and even rarer in 4wd models. Only problem is mine is 2wd, and I'd like to make it 4wd. I've done a lot of research before I even picked it up, and it looks pretty straightforward. Cherokees are dime a dozen around here (mind you 95% of them are rotten underneath, we use salt on the roads up here) so picking up a parts Cherokee shouldn't be hard. My questions for this swap are, the Comanche I bought is 5 speed, I'd like to keep it that way only problem is that the 5 speed in a Cherokee is rare here, can you make a 2wd 5 speed into a 4wd? Is there another jeep 5 speed that will bolt up to the 89 4.0 and use a tcase? Other than that I'm fairly mechanically inclined, I'm a millwright by trade, but is there anything I should look out for as far as problems or issues people have had? And what year Cherokee should I shoot for when looking for a donor . Thanks

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Hi.   :waving:  Welcome to the madness.

 

First off, the conversion of a 2wd trans to 4wd is more expensive than finding a 4wd trans.  Your best bet is to continue searching for a 4wd XJ.

 

You should search for an XJ that is 94+.  These have the better AX15 and the external slave cylinder.

 

Your 89 may have come with a BA10, or it may have an AX15.  Both have the internal slaves.  Jeep changed trans mid year.

 

AX15s from mid 89 to 93 all used the internal slave cyl.

 

The transfer case should match the AX15.  If you buy a parts XJ that won't be an issue.  The tcase input shafts changed when Jeep switched from the BA (21 splines) to the AX (23 splines).

 

The front drive shaft from the XJ will fit without adjusting.  Your MJ rear drive shaft will need to be shortened.  The XJ rear DS will be too short.

 

With the change from internal slave to external slave, you will need a new slave cyl.

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Also, if you plan on keeping the gearing the same you need to find a manual cherokee. Your rear axle, stock anyways, will be 3.07. You need a matching front axle. An automatic transmission will be 3.55. Try using car-part.com to source some things. Also, how are the pick and pulls in your area? And I hope you enjoy your truck. Mine has been the best vehicle I have ever had.

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what are your plans for the future of this truck?  daily driver?  offroader?  (please don't say winter transport)

 

as stated above, complete 4.0/auto XJ will give you a pair of 3.55 geared axles, t-case (and shifter) and a front driveshaft.  you'll then need a 4wd AX-15 trans and a rear driveshaft.  make sure the parts you need are in good shape before buying a donor rig.  car-part.com might help with your junkyard searches. 

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Nearing completion of my 90 2wd to 4wd conversion. It is a manual that came with 3.07 gears. I found a 97 YJ 4wd AX-15 on Craigslist, re-clocked it. Also purchased a 8.25 rear with 3.55 gear from a 2000 xj. Front axle and np231 from a 98 auto xj. Took the front driveshaft and had it shortened for $39. Rear driveshaft from a 92 2 Wd xj (just swapped out front yoke) New brakes, shocks and now in the process of converting it to obd1 after I install a rebuilt 98 4.0 motor. All this in a year and about $5000 and I'll have a almost brand new 26 year old truck. You should not have any problems finding the parts. Just study the tech section it contains all that you will need to do whatever you want to your truck. Happy hunting!

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Thanks for the info so far fellas it's greatly appreciated. To answe the question about the pick and pulls in my area, little to non exsistant, very few yards will even allow you to take a stroll through let alone take it off yourself and you get charged through the roof because of it, that's why buying a donor xj is my cheapest and easiest option. As for the plans for the truck, I want it as a daily driver/weekend warrior. But I have no intentions of beating the S@!T out of it, I have a woodser Cherokee for that, which I would use the housing and rest of the drivetrain for, except it's auto and it's been put through the ringer so hard I don't think anything on it would ever be salvageable for road use again, as well as its a limited so it has the 242 tcase which I don't really want lol lotta fun in that thing. Anyways that's a different story for a different day. So with the ba tranny(which I believe I have), will an ax-15 bolt up to my 4.0 ? And will the clutch assembly/flywheel be the same or would that have to be swapped? Then with the axles, I know the Dana 30 is a direct swap, but the rear axle (whatever it may be) out of the xj, I read somewhere that the spring perches are further apart on the mj's, is this true? Would it be better to buy new spring perches or cut and re weld the ones from the xj axle? Again thanks so much for the info.

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An AX15 will bolt right up to the 4.0.  No problems.

 

I just swapped my BA to an AX in August.  I kept the same fly wheel.  

 

I purchased from Rockauto.com a Clutch Master and Slave Cyl Assembly.  I went to an external slave AX15.  If you go this route, beware, the later model master cyl have a larger bolt pattern to the fire wall.

 

With an external slave, you could replace just the slave and clutch hose.  If you keep the internal, you will need a new internal slave.  The BA and AX are diff.

 

To swap the rear axle from an XJ will require re-positioning the brackets.  The XJ is SOA and is wider apart.  The MJ is SUA and narrower.  The shock mounts have to be relocated, also.

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