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97 2wd 5sp to 4wd

JeepGodXJ

NAXJA Forum User
Location
Oceanside, Ca
So about 6 years ago I had to sell my XJ for financial reasons. Had to do the adult thing and get a WJ for the kids. Don’t get me wrong, I love the WJ but my heart still lives with the XJ. I’m finally able to afford a cheap little project and came across a 97’ 2wd with a 5spd that I’ll end up converting to 4wd. I already know the process and what I need so that’s not my question. I have a 242HD that’s currently in my WJ. I still have a perfectly good 247 that came out of it sitting in the garage. When my son starts driving in 8 months he’ll be taking over the WJ. When that happens I’ll most likely be swapping back in the 247 so he can’t do burnouts in 2wd. (WJ has the 4.7 and Variloc’s)

So finally here’s my questions. Can the 242hd be used when I convert it to 4wd? I know the regular 242 will bolt right up to the AX-15 (I’ll be getting a 4wd ax-15). My concern is the input shaft spline count on the 242hd. I can’t remember what it is for the life of me. I know the output is 32 however. Anyone ever done anything like this before? Side note, anyone know where the 97 2wd Vehicle Speed Sensor (VSS) would be since it’s normally on the t-case? (I’ve heard it’s on the transmission) I know I can convert the 2wd ax-15 to a 4wd model so here’s my thought:

1. Convert ax-15 to 4wd.
2. Use VSS on transmission so my spedo works.
3. Use my 242hd (it doesn’t have a VSS input)

I know there’s a lot more factors with the conversion but this is my main concern. Sorry for the book. This is the result of 3 cups of coffee and being able to get into XJ’s again after 6 years. Any input on this is greatly appreciated.


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The 242HD has a much longer length of input shaft sticking out the front. You'll need to swap the input shaft with one from either a late model 231J or 242J. The early models have a different gear cut that won't mesh but input shafts are otherwise swappable across the various 231, 242 & 247 models.

Secondly, the 242HD typically has a huge tailshaft hanging off the back. You're into driveshaft mods anyway going to 4wd, but the longer tailshaft is very counter productive. There are hack-n-tap kits available for the 242HD, which I and anyone else will highly recommend while you have it apart to swap the input shaft. Otherwise you're going to need a WJ front yoke for the driveshaft to match the 242HD output. The front shaft out of any Jeep of that era will get you the components you need with the H&T, you may get lucky and it be the right length but I wouldn't bet on it.

As a note on the 242J in an XJ, the front output is located about 3/8" further back than a 232J, but the front driveshafts are the same. I don't know what you're plans are lift wise, but the spline engagement gets real short if you keep the wheelbase the same or longer with aftermarket lower control arms. Rather than buying something up front, waiting until the end to measure would not be a bad idea. I spent more replacing joints and balancing an oem shaft trying to fix the vibration than I did on a Tom Woods custom once I realized what the real issue was. That said, you won't have issues with stock LCAs.
 
Regarding the other part of your question, the 2wd AX15 has a tailhousing that contains the speedometer sensor opening. Once converted to 4WD, the opening will not longer exist, so you'll need to find a solution to not having an opening in the 242HD. It appears that the 242J and 242HD mid-housing are the same but that's just a guess. No opening means no gear inside the 242HD but it appears that it's just a matter of installing it, but that's just another guess on my part.
 
^ what he said, there's no vss opening on the WJ cases at all. The drive gear is cut into the output shaft directly on most nvg tcase designs since the early 90s, and I believe the WJ ones don't have it at all nor anywhere to install one, but I'm not 100% sure of that. I would go into this assuming you will have to swap more parts on it to make it work than it's worth, seeing as you can get NP231s for around 100 in most areas.

The AX15 has the vss port on the tailhousing on 2wd models and a drive gear for it on the output shaft. But on 4wd ones there is neither a gear nor a port in the tailhousing, nor space to install or machine either. To convert an AX15 to 4wd you basically end up completely disassembling it, swapping the mainshaft, then completely reassembling it with a 4wd tailhousing as well. Having done it, it's a great time to do a full rebuild because you are doing literally all the same labor except for replacing the input shaft bearing and front countershaft bearing... And will probably cost you more than a usable junkyard 4wd AX15 too.
 
Thank you for all the great information! This pretty much confirms what I thought. I thought just maybe it might work, but oh well. I love The 231 command trac. I’ll just end up buying one from a junkyard and rebuilding it if need be. Way less of a headache.


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