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Project 4wd conversion


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I have a '87 2wd 5 speed SWB comanche and would like to swap the 4wd out of my '98 XJ cherokee classic which has the 4 speed auto and the 8.25 rear axle I think. The easiest way I can think of is to swap in the auto trans with transfer case and axles.

 

The questions are:

Will it be a direct fit?

Will the computer in the '87 recognize the auto tranny/transfer case? And if not what do I need?

Will the driveshafts fit without getting new ones? As in are the wheel bases the same?

I bought 2 inch spring spacers for the front coils because the front end sits lower, are the 4wd springs longer?

Should I buy new springs when I am doing this?

 

I would like to update the gauges because I have the retarded HUGE fuel gauge if anyone has a spare with tach.

I am also looking for a drivers side seatbelt in black for my bench.

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Do both trucks have the same motor?

 

Computer has nothing to do with the transfercase. That's all manually controlled with the shifter.

 

Your front driveshaft will fit, you will need to have a rear one made. (Cut down your 2wd one)

 

Axle will be a direct swap bolt in swap. You'll need to bleed brakes however, since you need to retain the 98 brakes.

 

The front of MJs is supposed to sit lower. Most pickups do. It's so the rear doesn't sag when you're loaded down-you just even out.

 

As for the Transmission. I'm not 100% sure on the inner workings of the AW-4. I do know, however, that the 98's ECU controls the transmission, and does not have a separate TCU.

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I really don't know how the wiring for the AW-4 or what generations will interchange. I know you will have to use a TCU, as for if your current one will work, someone else will have to chime in.

 

After 7 XJs and 3 MJs only my most recent, my 8th XJ, has been an automatic. I haven't had it for a month yet and haven't had to make any major repairs, so when it comes to the autos, I'm at a loss.

 

If you feel like converting to a 5 speed, however, I should be able to help you out with most of that.

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I was going to keep the 5 speed but it seems like this board can't stand the older 5 speed because of it's durability so I was going to make it an auto. I would like to keep the 5 speed just because I miss a manual tranny but does the trans mount to the transfer case without new parts? I thought the spline count was different, and the length of the output shaft was different? I just don't want to put it in and then grenade it. I am just going to use it as a daily driver so I will not be going off road much with it.

 

Thanks again for the help, I can't wait to get started!

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You cannot simply throw a transfercase onto a 2wd transmission. You will need a 4wd transmission.

 

For some reason I must've misread your original post and thought you 87 was already an automatic. :doh:

 

If you're referring to the BA 10/5, then yes, it's not a desirable transmission. Idealy you'd want to find an AX-15 to throw in. You'd be looking at less work to retain a 5 speed and throw in an AX-15, but you'd have to find one. The T-case that's on the back of the tranny in the XJ should bolt up to an AX-15. AX-15s can be found in any mid 89-99 XJs and mid 89-92 Comanches with the 4.0/5 speed. I believe the changeover was the same for the YJ, so mid 89-95 YJ and 97-99 TJ.

 

If you do go with the auto, I know you'll need a Renix era flexplate, I'm not sure which converter you can use.

 

Your easiest and cheapest route would be to get a 4wd BA 10/5 + TC to throw in. It would go right in with no modification. You could then slowly assemble all the parts needed for an AX-15 swap, and just throw that in if the BA grenades on you. The T-case in your XJ will not bolt up to a 4wd BA 10/5.

 

Also, what I said earlier about the front driveshaft will only work if you put the automatic in. The autos are about an inch longer than the manuals(BA 10/5 and AX-15 are the same length), and if you use the auto shaft with the 5 speed, the slipjoint will be compressed more than usual and you could run into binding issues.

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It sounds a lot more complicated than I figured. It would seem I should abandon the XJ and just find a new donor with all the correct parts to begin with. If the auto doesn't work with the computer than I should find a xj or comanche 4wd with the ax-15 and a set of D44's. I may be dreaming, but if I can't use all the parts of the xj it would seem silly to remove parts to a good truck now.

 

I will look around for some parts at local jy's.

 

Thanks so much for your feedback, very helpful.

 

I live in the middle part of MI so I enjoy your offer but I will let someone who needs the trans more than I do have the chance of a freebie.

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Yes the same motor, 4.0. So your saying that the '98 ECU controls the trans so will I have to use that ECU? If so what will work and what won't?

 

Thanks for the info!

 

no. 98 ECU is not compatible AT ALL with your wiring and engine, and vice-versa.

 

 

the 98 trans has some extra sensors etc. and it probably won't work without someohow modifying it. i don't know what the mods would be, I just know you're better off going with a 96 and older trans/t-case.

 

 

the cherokee rear axle is NOT bolt-in. the comanche spring perches are spring-under and wider thann the cherokees. the cherokees are spring-over and narrower than the comanches.

 

 

I was going to keep the 5 speed but it seems like this board can't stand the older 5 speed because of it's durability so I was going to make it an auto. I would like to keep the 5 speed just because I miss a manual tranny but does the trans mount to the transfer case without new parts? I thought the spline count was different, and the length of the output shaft was different? I just don't want to put it in and then grenade it. I am just going to use it as a daily driver so I will not be going off road much with it.

 

Thanks again for the help, I can't wait to get started!

 

 

 

 

nonononononononononononononononono

 

the automatic trans uses a flex plate. the manual uses a flywheel. so, because the crankshaft position sensor operates off of the flywheel/flexplate "windows", and because the H.O. is timed differently than the renix era, those "windows" are different.

 

thus, the flywheel/flexplate are NOT interchangeable.

 

 

FYI you have to change some wiring to do an auto conversion as well, and you need a factory auto trans ECU

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  • 2 weeks later...

I abandoned the 4wd conversion for now, I just bought a '01 cherokee so I will leave the comanche 2wd for the forseeable future. Thanks to all for the great advice and I will keep the comanche for a project truck, first floor pans.

 

With 2 jeeps now I will have a little time to tinker with the comanche and drive the cherokee.

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I just did this conversion and if the MJ wasn't free, I wouldn't have done it. :brows:

 

Stupid stuff like the complete brake pedal assembly from an auto (for the torque convertor to lock up), an auto steering column, shifter, TCU and then the process of studying the hell out of the factory wiring harness to make it work (my roomate did that). The throttle body needed be changed (the '87 manual one doesn't have the necessary threaded holes), the TPS needed to be changed and wired in, tranny cooler lines (and those damn plastic GM fittings). The mosty odd install was the POWER/COMFORT switch (easier at the time than wiring in a bulb and if you didn't the tranny stays in confort mode).

 

If you have a COMPLETE donor vehicle side by side it is way easier. We were lucky and had three donors. :D

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  • 5 months later...

I have made up my mind. After much deliberation about what I want I am going back to an automatic. The donor I have is an automatic on the column so I will have to get the necessary shifter for the floor from an XJ in the JY sometime. As much as I would like to keep the manual it would be much easier to go with the auto. Because of the needed driveshafts and crossmember parts I would have to find anyway this seems like the logical choice. I have driven an auto 4wd comanche and it rode like a cadillac on the road. Not to say that mine will with the 3 inch lift provided by new rear leafs from hell creek and the new springs I got with the donor truck.

 

I plan on replacing the ball joints and upper and lower control arms with new bushings for the front end. I ordered an adjustable trac bar from hell creek also. The brakes are relatively new, will make sure everything is good before installing the axle. I will get new brake hoses too, and oh yeah, shocks also. I will install a moog trail boss steering damper on the front axle too. I don't know why they paint them white? I will repaint it black to match the other components.

 

For the rear axle I am going to replace the axle seals and fluid. I will sand blast and grind any rust and paint before installing. I found the U-joints are bad, not to suprising so they will be new spicer joints.

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  • 5 weeks later...

I have a few questions...

 

I am a little puzzled on what to do now. I have a donar 4wd aw4 on the column comanche, but I don't think I want to go through the hassle of changing my 5 speed ba-10 2wd over to the auto 4wd.

 

Will a 231J 4wd transfer case from a '93 XJ work with a AX-15 4wd manual trans? I have heard a lot about spline counts and output shaft lengths so I want to make certain it will work before collecting parts.

 

What is the difference between 231 transfer cases?

 

What should I do? I would like the easiest way of putting it together, which seems like a ax-15 but with what parts? I don't want to just start buying parts if the driveshafts are different and such.

 

Thanks all!!

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I have a few questions...

 

I am a little puzzled on what to do now. I have a donar 4wd aw4 on the column comanche, but I don't think I want to go through the hassle of changing my 5 speed ba-10 2wd over to the auto 4wd.

 

Will a 231J 4wd transfer case from a '93 XJ work with a AX-15 4wd manual trans? I have heard a lot about spline counts and output shaft lengths so I want to make certain it will work before collecting parts.

 

What is the difference between 231 transfer cases?

 

What should I do? I would like the easiest way of putting it together, which seems like a ax-15 but with what parts? I don't want to just start buying parts if the driveshafts are different and such.

 

Thanks all!!

 

 

The easiest of easy is to get the cherokee or comanche equivelent of exactly what you want to run and swap everything over. You will have every bolt, shifter, cable, etc. to make it happen.

 

Sounds crappy but it is by far the easiest but you can see how it is supposed to look before you install it.

 

231s are basically similar over the years with some internal changes and some different input splines. Just find the one to to work on your transmission of choice. (Don't know about the AX-15 but I would assume it would be a 21 or 23 spline).

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Thanks for the reply, still not completely convinced. How do I know how many splines the trans has compared to the transfer case so I know they will match up? I am thinking of taking a transfer case out of a truck but I want to know if it will work with a manual trans instead of the auto it's in now.

 

I hope I am not making this to difficult,

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All AX-15s are 23 spline output.

All Peugeots are 21.

I believe AW-4s changed from 21 to 23 in 91

all transmissions behind 2.5Ls are 21 spline

 

 

the cherokee rear axle is NOT bolt-in. the comanche spring perches are spring-under and wider than the cherokees. the cherokees are spring-over and narrower than the comanches.

 

close :D

 

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  • 10 months later...

I have been up and down on this one. If I find a suitable donor again '87-'90 for the trans and transfer case should I have the trans rebuilt before installing? I can't see putting a 160k trans and transfer case into a newly restored truck. If I had to what would be the cost of doing so? I thought about buying a newer (post '91) trans but I guess the electrical connectors don't mesh.

 

I want to buy a donor truck for all the necessary parts but don't want get stranded when the aged trans or xfer case clunks out on me.

 

Has anyone had their trans and transfer case rebuilt and how much should I expect to pay?

 

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I have been up and down on this one. If I find a suitable donor again '87-'90 for the trans and transfer case should I have the trans rebuilt before installing? I can't see putting a 160k trans and transfer case into a newly restored truck. If I had to what would be the cost of doing so? I thought about buying a newer (post '91) trans but I guess the electrical connectors don't mesh.

 

I put a '95 AX-15 and TC into my '90 and the connector for the reverse light was the only connection and it was the same, so if that's what's stopping you, don't let it. Your's is a 5 speed right?

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I went through this same conversion. I started off with a 88 Jeep MJ, Renix 4.0L, 2wd, Ba5/10. It makes things much easier if the donor is also a Renix 4.0. I found a 1989 Cherokee for $300 on craigslist which was rear ended. Frame was damaged but axles and all were OK. It ran well, and had 180K on the ODO. So now i had my project and a suitable donor. My engine was making a low knocking noise at some rpm's so i decided to do an engine swap as well while i was at it. It is best to keep the donor until your conversion is %100 complete. you never know what you might end up needing.

 

Anyways it wasn't too bad. Me and a buddy did it in about 1 1/2 weeks. I have a very organized and well equipped work area/shop in my backyard (dads a mechanic) and 10 years experience working on cars. I am 23 years old.

 

You will need to swap in the old auto ECU, auto TCU, Wiring harness which plugs in to ECU (including all sensor wiring/relay block), small trans harness which plugs into TCU behind passenger lower dash, comfort/power switch, throttle body, speedo cable, trans/tcase as a unit, donor d-shafts, shifter assembly / cables, etc, etc. Be patient and make sure you do it right the 1st time. There is alot involved. It becomes very difficult to diagnose any problem after a project this big. You have moved so much around that sometimes you may feel overwhelmed. It almost happened to me after my swap when i overlooked the ECU grounds. Make sure to clean them up and get them nice and snug, they go behind the oil dipstick on the bolt. When i was done che fired right up ad runs like a top. I used this "old" engine and trns and had great results. Engine runs much better then my old 4.0 which had around 300k, and has VERY good oil pressure. Trans was servced at time of conversion with new filter and fluid and it shifts perfectly. Trans fluid is still rosey red and smells as it should. Ive been driving it for 4 months now and have had no issues whatsoever. Only issue i had was related to the engine swap and not the 4wd conversion. I had a substantial leak from my oil pan and had to drop it to replace gasket and rear main seal. When i did i insopected the main crank bearing which i removed to replace rear main seal. i was soo surprised at the PERFECT condition that i found it to be in. I checked the back and it was standard size with the original AMC logo on it. Wow... what an engine, it really was hard to believe any bearigs could look that good after 180k miles. I put it all back together and now have gained peace of mind. I know my engine is good to go/has been well taken care of. After that my MJ hasnt leaked a drop, and runs like a champ.

 

Your best bet is to find a suitable 87-90 Renix Cherokee/Comanche for your donor. Once you find one of these, you can be sure you have EVERYTHING needed to make your MJ 4wd.

 

The only thing which i needed to have done was my rear drive-shaft. The MJ has a longer wheelbase than the cherokee, and thus the rear xj shaft won't be long enough. I ended up having my old long Mj shaft cut down and re-welded to the correct size. It works very well.

 

Oh yah, the E-brakes also need to be modified to work somehow... its kinda tricky. I never got to that, as its no longer as important now that i have "Park" with my Auto.

 

Find your donor, and let us know if you need anything else or have Q?'s.

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That was the most concise answer I have ever gotten on anything. It wasn't the most engineer jargon laden piece but it doesn't need to be. I understand everything now. Thanks for your time and I will now be able to really look for a donor. If the trans is bad I will just have it rebuilt and suck it up. I think the truck is getting a little overpriced but I can't seem to stop now and compromise what I really want. Sometimes you want the easy out, but in the end I want to be happy.

 

Thanks so much for your advice.

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Your welcome. I normally wouldnt take that much time a make such a long post but I know exactly what positon you are in. I actaully bought my truck with a 4 1/2" lift on it, so it was really asking for a conversion. That and the fact that i was sick and tired of people complimenting my truck and then saying "oh.....WTF its not 4x4?". Now its my pride and joy. Good luck with yours.

 

Randy B.

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