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unibody swap?


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I found two same year, super cheap jeeps, a Comanche and a Cherokee, I want to transfer entire running gear from Cherokee to mj. Mj is 4cyl, 4 speed, 2wd, Cherokee is 4x4, 4.0L, 5 speed.

Is it possible to support engine and trans enough to actually swap bodies?

Will the rear axles be geared the same?

While the mj is all torn apart it would be nice to add a lift, maybe update fuel system. 

Ideas? Suggestions?

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First off, welcome to the forum, Shane!

 

Yes, it's possible to swap the drivetrain from the Cherokee into the Comanche.  The axle ratios of the Cherokee with that engine/trans. combo is likely a 3.07 and the Comanche will likely be 3.55 (could be 4.10, but doubtful).

 

Check the I.D. tags on the axles and see.  Pictures will be helpful to us as we can help you identify different parts.  You may be one of the lucky ones with a rare gem under your Comanche. 

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You can swap the drive train from one vehicle to the other, but not by swapping bodies. The XJ is completely unibody, and the Comanche is unibody to the back of the cab, with a frame grafted onto the back behind the cab for the box.

 

The axle ratios for the 4-banger is probably 3.55, the 4.0L is 3.08.

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If I understand the question correctly, and if you are going to lift it at the same time. Remove front suspension. Then drop motor, trans, t case as an assembly out the bottom. Is that what you're thinking about? Should work. You'll have to research the firewall and radiator support issue. Early MJ's had a different firewall and radiator support that makes such a swap a lot more work. As for the gears, you'll just have to check them to be certain.

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Ah! I see the plan. The problem with that plan is that the motor mount brackets are arms that stick out from the sides of the block and sit on top of the "frame" ears. Unless you want to fight with the bolts holding the motor mount brackets to the block, the motor has to come out by being lifted off the frame ears, it can't be dropped through them.

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Haven't fully looked at mounts, but I take it those bolts are not easy to get to or just difficult to get out? Probably just easier to pull engine and drop tranny? Or since the 4cyl does not have a t-case maybe pull engine and tranny at same time? Time to buy a cherry picker.

 

Looks like the Cherokee has the 3.07 rear axle, haven't found numbers on the Comanche yet. Wheel base is 12" different but I would just lengthen the rear drive shaft right?

Any easy mods to update fuel system?

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If I understand the question correctly, and if you are going to lift it at the same time. Remove front suspension. Then drop motor, trans, t case as an assembly out the bottom. Is that what you're thinking about? Should work.

That would be a very tedious way of going about removing the drive train...  Much easier to remove the front header panel and radiator, remove the starter and O2 sensor, and pull it all out through the hood.

 

You'll have to research the firewall and radiator support issue. Early MJ's had a different firewall and radiator support that makes such a swap a lot more work.

That was only an issue with early '86 model MJ's.

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You specified that both Jeeps were of the same year, but what year though?

Also, it should be a direct swap.  You will have to swap the interior wiring harness, which involves removing the dash.  A custom (but easily made) harness will have to be wired to allow your fuel pump and tail/brake lights to work with the XJ dash harness.  Some modification will be need to fit the 4.0L fuel pump in the MJ's fuel sending unit (which isn't hard to do).  I did the same swap a couple years ago in my MJ, but mine was a little more involved since mine was an '86 and it has the aforementioned differences with the firewall and front crossmember (under the radiator).

 

Read through my build thread to get you familiarized with what's in store for you.  Again, don't concern yourself too much with the fabrication/metal working that I had to do as that will not be applicable for you.  Build thread: http://www.cherokeeforum.com/f46/86-comanche-dd-159524/index3/#post2533898

 

Also, this should be some aid also.  Look through some of these: http://comancheclub.com/topic/39539-links-for-25l-to-40l-swap/

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Shane - you can pull the Engine, Transmission and Transfercase as one whole unit. Use an engine load leveler front to rear and it is very easy to pull with the radiator and front header panel removed. I generally use the front and rear bolts with studs on either end of the head and the passenger side motor mount as my chain up locations. Has work well for the 6 times I've pulled and installed a 4.0/trans/case combo.

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I have dropped the assembly out the bottom before, I thought it worked pretty good. But, I have things set up differently in my shop than others do, so basically what ever you think will work best for you will probably be the way to go.

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1987 swap, so since I have no garage space to use or a cherry picker. I will probably still try to pull mj bed and drive shaft first, disconnect all linkages and suspension from body, remove motor mounts, and swap uni bodies, haven't gotten very far yet between working full time and having snow on the ground with more coming lol.

 

I don't really plan on doing much with the Cherokee body and 4cyl 2wd drive train, so I will probably just loosely bolt it up and try to sell as parts. Probably keep the fenders, front doors for half doors, they should fit right?

 

For the budget lift, Was going to try using a combo of spring leafs from both vehicles and maybe some new shackles for the rear, and the front new springs or spacers? I prefer new springs but does anybody suggest against spacers? They are a lot cheaper. I only want maybe 3" should I use the cross member drop spacers?

 Any cheap fender flares out there?

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Doc any advice on supporting everything during body removal? or is it just a combo of whatever jacks and wood blocks that are available? I work on skid steers mainly but after I made some cash on a quick Cherokee flip and doing a friends Cherokee clutch I felt confident building my dads old truck.  Hoping to get roommates and neighbors to help carry bodies to other drivetrain lol.

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^^^that.

Not sure you understand. The frame is part of the body. You can't separate the two without striping pretty well everything and drilling out thousands of spot welds. There's no convenient one-piece subframe or anything. Lifting the body off the drivetrain is going to be lifting the entire vehicle minus whatever you pull off. Better have a LOT of friends is right.

 

This summer, I swapped a 4.0 with trans and tcase as a unit from an XJ into my MJ in my back yard. That's grass beside a gravel driveway. I threw down a few sheets of 3/8 plywood to make myself a dancefloor and got to work with a cheap harbour freight-type cherry picker.

DULZ0iC.jpg

Sure it was a pain rolling around that much weight by myself without a level floor, but way less of a pita than lifting the vehicle off everything.

 

Also, I had to change a hydrostat in a skid steer at work this summer. Most awkward thing I've ever done, there's nowhere to sit or stand or anything. But it was still less awkward than what you're planning.

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I have an overhead chain hoist thing in the shop that I made years ago. So basically I supported the engine/ trans and hoisted the body off of them. I don't know how much an XJ weighs without motor/trans but I'm sure wouldn't want to be one of the people asked to help lift it. I know the back of my bobcat gets pretty light when I've moved a shell around though.

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