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91 4wd conversion


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Trying to help out a new C.C. member.Ran into a young Comanche owner (SAKI 19) shortly after I  bought my Comanche,Now he's thinking about converting to 4wd. if it can be done simple and cheap enough.He has a 91 4.0 Automatic What would be the best year X.J. doner for the conversion.I know a 91 4.0 4wd,Automatic would be the best but what other years would work as far as being the simplest and cheapest swap.I know to stay away from the Renix years but what other years after 91 will work.Thanks

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Any AW4 will work. You're better off with the 97+ up ones for two reasons. One, they're newer, and two the transfer cases are sealed units so if you need to you can run in 4wd with just the front drive shaft without the TC losing fluid. Very handy if you blow u joints and don't have replacements with you.

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As commando stated there are several combinations, but if you guys are looking to buy a complete donor and have everything there 91-95. (minus rear driveshaft) There are several write ups around web and on C.C. It is a very simple swap

Would also like to add to use the boostwerks shift linkage I believe commando is who first turned me on to it, WORTH EVERY PENNY! BTW commando great find I was about to pull my hair out with that stock linkage!

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Thanks,I'm doing a 4wd. conversion on my 89.(Half way through and my back/sciadic nerve went out,On hold till it heals up a little)I.m going from a 5sp. to a Aw4 /242 combo.Will that type of linkage work with that application?Thanks

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Thanks,I'm doing a 4wd. conversion on my 89.(Half way through and my back/sciadic nerve went out,On hold till it heals up a little)I.m going from a 5sp. to a Aw4 /242 combo.Will that type of linkage work with that application?Thanks

Thanks

Absolutely, even better you don't have to source all the oem linkage parts. Everyone is correct, but because you asked the simplest route 91-95 would be it. As far as the vac disconnect goes it is a non issue they stopped this in 92 i Believe also some 96 are obd1 but beware it is a bastard year to obd2. Now saying all that obd2 trans can be made to work with obd1 with simple wiring changes as you can see there are several route all of which can be made to work fairly easy good luck

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Thanks guys,I kinda through in my swap to the original ? when I read about the linkage.I have an 88 X.J. doner allready for my 89 conversion,It came with a hi pinion non cad D-30 AW4 and NP242.I allready have the front and rear (3.55) axles under my truck.Done the axle swap first so I can remain driving my truck untill I have to get the driveshaft shortened as it's my D.D.I still have to pull the Trans. and T.C. and install once my backs up to it.I encouraged the boy with the 91 to buy a doner X.J. Everything he needs will be there(except rear driveshaft).All the nuts bolts wires hoses ect.I noticed there is a set or holes on the tranny hump of the X.J. for the T.C. linkage thats not on my 2wd. M.J. I don't know how one would even know where to drill them if you just gathered up all the parts.Around here you can buy a good X.J. with a bad motor for $400-$500.A bad motor tells me the rest of the drivetrain should still be good.Just trying to keep it cheap and simple for him.Will be looking for a 91-95 X.J. Doner Thanks again.

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Thanks guys,I kinda through in my swap to the original ? when I read about the linkage.I have an 88 X.J. doner allready for my 89 conversion,It came with a hi pinion non cad D-30 AW4 and NP242.I allready have the front and rear (3.55) axles under my truck.Done the axle swap first so I can remain driving my truck untill I have to get the driveshaft shortened as it's my D.D.I still have to pull the Trans. and T.C. and install once my backs up to it.I encouraged the boy with the 91 to buy a doner X.J. Everything he needs will be there(except rear driveshaft).All the nuts bolts wires hoses ect.I noticed there is a set or holes on the tranny hump of the X.J. for the T.C. linkage thats not on my 2wd. M.J. I don't know how one would even know where to drill them if you just gathered up all the parts.Around here you can buy a good X.J. with a bad motor for $400-$500.A bad motor tells me the rest of the drivetrain should still be good.Just trying to keep it cheap and simple for him.Will be looking for a 91-95 X.J. Doner Thanks again.

There are dimples in your 2wd where to drill but like I said get the boostwerks you won't regret it!
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That Boostwerks set-up is sweet.

 

Here is something that I have posted before. Maybe it will give you some helpful info...maybe not... :dunno:

 

I did this last spring. Pretty simple as the 2wd beam axle uses all of the same suspension as the solid axle from the 4x4. If you can use a wrench you can do this swap on the front. Unbolt one, bolt in the other. A couple of hours work.

 

You will need a matching AW4 and transfer case. Spline counts changed some between years so it is easier to get a matched set and get one as close to the year of your truck as possible to alleviate any possible electronics matching problems. Some claim issues with swapping years. I used a '96 set-up in my '91 with no problems. Obviously XJ donors are the most plentiful.  Get the t-case shifter at the same time or use the option below. Drop the fluid lines & shifter linkage, drop the rear drive shaft being careful about the fluid in the tranny,  unbolt the 4 converter to flexplate bolts, unbolt the bell housing ( the top two are a weird inverted torx thingy...can be a PITA), drop the cross member, & as you drop the tranny disconnect the electronics. Be sure to keep the cross member & mount oriented correctly as they can go back together backwards and cause alignment issues. Attach the electronics/speedo to the new pieces, hoist it in place, & re-install the crossmember as it is the same for 2wd/4wd. Attach the bell housing bolts, attach the flex plate bolts, attach the lines. You will need to screw with the exhaust as the main hanger is attached to the cross member. I took my exhaust completely off to weld up the manifold and to go custom past the head pipe. If you are going to go off-road in any kind of wet area take this time to extend your tranny breather tube. It is much easier out of the truck.

 

The t-case shifter can be a royal pain to source and mount especially in the rust belt. A far better solution, both in ease of installation and later performance, is this shifter linkage: http://www.boostwerksengineering.com/231-HD-Shift-Linkage-Auto-Trans-_p_25.html . That is $38 well spent. To install the shifter itself pull back your carpet and unbolt the access plate. Bolt the t-case shifter into place from the interior side. Attach that new linkage from below. Attach the original tranny shifter linkage.

 

The front drive shaft is pure XJ. Maybe grab it with the tranny & stuff. The rear drive shaft is more tricky. First of all the original is too long and will need to be shortened. The new length will depend on the t-case and rear axle that you use. here is a chart that will help: http://comancheclub.com/topic/18925-looking-for-driveshaft-lengths-of-stock-trucks/   .

The next problem is that that although the 4wd trucks used a conventional rear drive shaft from the factory the 2wd trucks used a bizarre ( and giant) two-piece arrangement with an inner and an outer tube. In between is a full-length rubber sleeve that connects the two tubes. That rubber makes re-welding harder and the shaft often cannot be re-balanced if that rubber has shifted over the years. You cannot get an XJ shaft as the MJ has a longer wheel base. That leaves having a custom shaft built or doing what I did: I found a conventional shaft in the pick-in-pull that was longer but used the same 1310 u-joints. I had this shortened and re-balanced as that is usually about a third of the price of a custom shaft.

 

needed:

4wd AW4 & matching t-case

 

T-case shifter & boot

 

t-case linkage

 

front driveshaft

 

Front Dana 30 HP front from an MJ/XJ in a gear ratio to match your rear. ( the early CAD axles are less desirable and use smaller u-joints. '96-99 up are better donors. A 2000/2001 XJ or a TJ front end will bolt in but they are weaker low pinion designs and it will be hard to match the ratio with a tj front. )

 

custom rear drive shaft of one flavor or another

 

 I tried to make this as complete as possible but I may have forgotten something. Good luck.

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Incommando,That helps a bunch.Very detailed,Gonna order the Boostwerks linkage for sure,wondering why my 88 XJ. doner has a non cad front end, Maybe cause of the select trac T.C.  The boy with the 91 is now looking for a 4x4 instead of converting Thank again.

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