grampa7 Posted January 7, 2013 Share Posted January 7, 2013 I am an old rookie. Have always thought the Comanche was just exactly what a pickup should look like. I have a chance to get an 87 4.0L 2wd 5sp, but would like to convert it to 4wd automatic. Any thoughts on (1) how involved, (2) pitfalls, (3) helpful hints, (4) things to absolutely stay away from? As far as I can tell (rookie, remember) the 87 is entirely stock. Thanks. Grampa7 Link to comment Share on other sites More sharing options...
Dadinator Posted January 7, 2013 Share Posted January 7, 2013 I did just the opposite. Converted an auto to 5 sp. Mine was already 4x4. The best advice I can offer is get a cherokee of the same year to use as a donor. It doesn't have to be the same year, but the closer the better. Just get one of the same vintage. (87-90) would be your 1st choice. Then you can swap everything over directly. Small things to consider: Your rear driveshaft will have to be modified or replaced as it will need to be shorter. You will need to make sure that your rear axle and front are geared the same or have one of them changed. Everything on the cherokee from the cab forward will swap directly. From the cab back, it won't. So If you use the cherokee rear axle, you'll have to modify it to fit on the MJ. It's not the hardest thing in the world to do, but It will be pretty involved and not for the light hearted. But fun if you are into these kind of things. Link to comment Share on other sites More sharing options...
jimoshel Posted January 7, 2013 Share Posted January 7, 2013 So where you located? I've got a '87 4.0, auto and I'm not a auto fan. Maybe we could swap. Link to comment Share on other sites More sharing options...
grampa7 Posted January 7, 2013 Author Share Posted January 7, 2013 I am in NE Ohio. That might be a bit of a hike to Colorado. I will have to see if I can figure out how to get my location on my posts like you have. Link to comment Share on other sites More sharing options...
HOrnbrod Posted January 7, 2013 Share Posted January 7, 2013 I am in NE Ohio. That might be a bit of a hike to Colorado. I will have to see if I can figure out how to get my location on my posts like you have. Click on your User name (Upper Rt. Corner) -> My Settings -> General Account Settings -> Location (Fill in in) Link to comment Share on other sites More sharing options...
Geonovast Posted January 7, 2013 Share Posted January 7, 2013 On the upper right of your screen, click on your name next to the sign out button. Go to My Settings, and scroll down to the bottom. You can enter your location there. You can also edit your signature and fill in your truck information, which will help us answer future tech questions. Finding an XJ with everything you want that's a Renix (87-90) is definitely going to be your ideal situation. If you keep it a 5 speed, it's fairly easy to piece a 4wd conversion together. The auto conversion is going to be the most hassle. You won't need to change your rear axle if you keep it a 5 speed. Link to comment Share on other sites More sharing options...
grampa7 Posted January 7, 2013 Author Share Posted January 7, 2013 Dadinator, Thanks for the info. Cool truck. Rich Link to comment Share on other sites More sharing options...
mvusse Posted January 7, 2013 Share Posted January 7, 2013 As stated above, get an 87-90 Cherokee with a 4.0/automatic/4x4 and swap everything over. Use the Cherokee axles as your current 3.07 gear ratio will suck with an automatic transmission. Front axle will be bolt-in, rear axle will need the spring perches and shock mounts cut off and new perches welded on. This will cost an angle grinder ($20), spring perches ($10 or so) and $20 for someone to weld them on, so not a big issue. This way you will have all the odds and ends and little parts you will need. Then have your current rear driveshaft cut down and rebalanced (~$100) by a drivetrain shop and you're in business. With a place to work large enough to park both vehicles side by side (preferably indoors with a concrete floor) and a good set of tools it could probably be easily completed over 3 weekends. I'm in NE Ohio also, but in the southwest corner of it (20 minutes south of Canton). Link to comment Share on other sites More sharing options...
Dadinator Posted January 8, 2013 Share Posted January 8, 2013 Dadinator, Thanks for the info. Cool truck. Rich Thanks! Link to comment Share on other sites More sharing options...
JFAComanche6 Posted January 8, 2013 Share Posted January 8, 2013 My conversion went great, but make sure you get a decent vaccuum harness for the front disconnect axle. I snap those stupid hoses every time I mess with my transfer case, but they're easily repaired. Theres a sweet replacement cable that you pull from inside the cab made by AlloyUSA for about $160 to solve the vaccuum harness crap, if you have $160. Link to comment Share on other sites More sharing options...
Dadinator Posted January 8, 2013 Share Posted January 8, 2013 Or lock it over permanently. Lots of folks (including myself) have done that with no looking back. Link to comment Share on other sites More sharing options...
Geonovast Posted January 8, 2013 Share Posted January 8, 2013 Really the only reasons for not deleting the CAD and buying that overpriced cable is if you have a spool in the front, or you have a real need for a 2wd low range. If neither of those apply, lock the thing and forget it's there. Link to comment Share on other sites More sharing options...
grampa7 Posted January 9, 2013 Author Share Posted January 9, 2013 This all seems like very useful information. It also seems like a great group of very helpful folks. Thanks. Rich Link to comment Share on other sites More sharing options...
Dadinator Posted January 9, 2013 Share Posted January 9, 2013 Best forum I'm a part of. And I'm on several. Link to comment Share on other sites More sharing options...
mvusse Posted January 9, 2013 Share Posted January 9, 2013 I must be one of the few that didn't lock the cad over. I chose to do a single piece shaft conversion instead. Link to comment Share on other sites More sharing options...
Geonovast Posted January 9, 2013 Share Posted January 9, 2013 I must be one of the few that didn't lock the cad over. I chose to do a single piece shaft conversion instead. Definitely the preferable choice, but when you consider that locking the CAD is essentially free and doesn't have the hassle of dealing with popping a unit bearing, dealing with that giant nut on the shaft, installing a new seal, and finding the one piece shaft, just locking it is going to be the way most people will go. You still got rid of the stupid thing. Link to comment Share on other sites More sharing options...
JFAComanche6 Posted January 14, 2013 Share Posted January 14, 2013 Really the only reasons for not deleting the CAD and buying that overpriced cable is if you have a spool in the front, or you have a real need for a 2wd low range. If neither of those apply, lock the thing and forget it's there. Would that cut down my MPG or wear my front axle out faster? it was locked in because of a bad vacuum switch, but I replaced the switch. Should I run a hose straight from the engine to the vacuum motor? Link to comment Share on other sites More sharing options...
Biotex Posted January 14, 2013 Share Posted January 14, 2013 The MPG lost is so negligable you don't have to even consider it. The factory went that way on all the newer jeeps. I look at it that everything gets lubricated better. Not sure it is true or not, but I like to think of it that way. Kind of like flat towing where you put it in gear so the oil gets splashed around. Like I said, maybe thats not the case on a front diff, but I havent seen any negatives to locking the CAD. Link to comment Share on other sites More sharing options...
Pete M Posted January 14, 2013 Share Posted January 14, 2013 the only downside to locking the front is you might find out that the front driveshaft needs maintenance (which you should be doing anyway so it's not that big of a deal), i.e. a bad u-joint can cause vibrations at speed. :thumbsup: Link to comment Share on other sites More sharing options...
jimoshel Posted January 14, 2013 Share Posted January 14, 2013 the only downside to locking the front is you might find out that the front driveshaft needs maintenance (which you should be doing anyway so it's not that big of a deal), i.e. a bad u-joint can cause vibrations at speed. :thumbsup: The way I'm always speeding, the whole Jeep vibrates. Can't pin it down to just one component. Link to comment Share on other sites More sharing options...
JFAComanche6 Posted January 14, 2013 Share Posted January 14, 2013 Okay, but do I have to do all that work like the link in Geonovast's profile? Or is it an okay idea to just run a vacuum hose straight to it? I'm a lazy and broke kid, by the way. Link to comment Share on other sites More sharing options...
Pete M Posted January 14, 2013 Share Posted January 14, 2013 a slightly easier way is to pull off the CAD cover, slide the collar over, and then re-install the CAD cover upside down. does the same job. :thumbsup: Should take you 5 minutes. Link to comment Share on other sites More sharing options...
jpnjim Posted January 14, 2013 Share Posted January 14, 2013 The only bad thing about disabling the CAD is those early NP231's would lock the ft & rear outputs together in neutral. So, If you flat tow in Neutral, with the CAD engaged, you risk stressing out, or damaging the t-case. When they eliminated the CAD entirely, they modified the transfer case so it no longer connected the outputs in neutral. ^^^this sounds insane, but if you have an early 231, put it in N and you'll see :) Link to comment Share on other sites More sharing options...
Biotex Posted January 14, 2013 Share Posted January 14, 2013 Okay, but do I have to do all that work like the link in Geonovast's profile? Or is it an okay idea to just run a vacuum hose straight to it? I'm a lazy and broke kid, by the way. Another way to lock it over instead of the upside down cover is to use a hose clamp. Just slide the collar over and put a worm style hose clamp onto the shaft to lock the collar from moving. Seen it done with no ill effects. Link to comment Share on other sites More sharing options...
chappy88 Posted January 15, 2013 Share Posted January 15, 2013 My son and I are attepting to convert 88 mj 2x4 manual to 4x4 manual. Best parts vehicle we have found so far is a 91, 4 door cherekee. The only major difference so far is the wheel base on the cherekee is approx 12" shorter than the mj. Anyone have any thoughts or ideas that could make tranision as painless as possible? Link to comment Share on other sites More sharing options...
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