Transmission Questions

Alright guys got a couple questions here. My 90 Cherokee Pioneer(4.0) has the four speed automatic transmission in it now and it just junked out on me. I'm trying to decide here if I want to just get my existing one rebuilt or get a manual put in. I'm not sure really I think right now I have the AW4 and I would need the AX-15 if I wanted to do a manual. So I need clarification on those serial numbers to make sure I'm talking about the right transmissions. Also what modifications would I need to have someone do if I decide to change to manual? Would I need a different transfer-case? I have the command-trac one right now.

I need help on this ASAP guys so if anyone can answer any of those questions that'd be great. Thanks.

You do have the AW4 automatic. You didn't say if you have Command-Trac or Selec-Trac, so your transfer case could be an NP231 or an NP242. In a 1990, the transfer case probably has a 21-spline input. Any AX-15 5-speed you find will probably have a 23-spline output, which means it won't mate with your transfer case.

The AW4 is a good transmission, but if you are certain you want to undergo the bother and expense of converting rather than either repair your AW4 or get another AW4 from a junkyard, your best approach will be to find a tranny and transfer case together. Note that you can use a YJ (Wrangler) tranny and transfer case, but the transfer case shift linkage in the YJ is totally different and you'll have some adapting to do there. Also, if you currently have a 242 transfer case (Selec-Trac), that wasn't an option in the Wrangler so to get a 242 you'll have to look for a Cherokee as the donor vehicle.

You'll also need the complete clutch peddle and brake peddle assemblies from a 5-speed Cherokee. I wouldn't bother getting the clutch master cylinder from a junkyard -- buy a new one, and a new slave cylinder and conncting hose while you're at it. And look for a later model AX-15 with the external slave cylinder. I'm not certain what year they changed, but with the early style if the slave cylinder fails you have to drop the tranny and transfer case to replace it. Dumb design.

Get a Howes clutch master cylinder. They are cheaper and are much better. Stock bore is .75"

yes, ax-15 or nv3550 out of a '01 or newer wrangler. I've got the nv3550 in my 90 and love it. You will either need to replace the transfer case with one from a manual or change the input shaft to 23 spline. I'm pretty for sure the auto's used 21 spline output shaft. If you go ax-15, get one with the external slave cyl. All the nv3550's have them. I believe the 95 and up ax-15's are external slave. The only modifications you would need to do that come to mind are:
1- Obviously, install clutch pedal, brackets, linkage, master cyl. etc.
2- Get the shifter boot and other related stuff from the console of the donor vehicle.
3- transmission mount I'm sure is different.
4- you may run into driveshaft length issues, but I'm not for sure on that.

That's all that comes to mind, but the biggest part of the job will be the pedals and shtuff. Oh yeah, duhhh....you'll need a flywheel and clutch assembly, including pilot bearing and possibly may need to bore the crank to accept the pilot bearing/bushing. Good luck, hope this helped!
Dale

Apparently I have the 231 because I have command-trac. I'm thinking about getting a remanned one from this place

http://www.phoenixhardparts.com/Mer...=PRT&Product_Code=AX15+Jeep&Category_Code=JMT

Will that one fit with my existing transfer case or not?
Once again any help ASAP would be appreciated.
Thanks a bunch.

Collin

You know guys its all good. I figured that my existing(although poorly) AW4 lasted 220,000 miles and that was with the fluid being changed after 210,000 and that was the only time so I'll just get mine remanned I think. I dont really know a whole lot about cars let alone transmissions and it sounds like even some people that know a lot had trouble accomplishing converting over. Thanks for the insight though.

that's probly your best bet to stick with the AW4. But I would look into buying a low mileage replacement from a boneyard as an alternative to having yours redone. Check on www.car-part.com . I've found some pretty good deals on there. Just bought a 2002 dodge neon motor with 18k miles on it for $300. That's my favorite web-site...well, except for this one

the aw4 is an excellent tra.s. it would probably be cheaper to replace it than to do a complete conversion

roXJeepr said:

that's probly your best bet to stick with the AW4. But I would look into buying a low mileage replacement from a boneyard as an alternative to having yours redone. Check on www.car-part.com . I've found some pretty good deals on there. Just bought a 2002 dodge neon motor with 18k miles on it for $300. That's my favorite web-site...well, except for this one

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The problem is he has a 1990 XJ, That has a 21-spline output. Anything "low mileage" will be out of a newer vehicle with a 23-spline output.

The tranny from Pheonix should work. You're buying it from them to fit your year, so it's their reponsibibility to ensure that it has the correct output shaft.

I took my Cherokee to Cottman Transmission guys, have any of you ever dealt with them or do you guys all do your own work? If someone here has ever dealt with them I would like to know what kind of work they do.

P.S. There's no way I'm going to convert to manual because it sounds like way more work than I could ever handle.(even if the splines did match up, thanks though for the help)

what actually crapped out about your trans?

I'm actually not sure what exactly went out. I really cant diagnose but I'll tell you what it was doing and you can go from there. I was cruising along at 55 you know it was at 2000rpms or whatever, all of a sudden it revved up to 5000 and I couldn't get any torque, so I shut it off and restarted, I regained torque for another 5 or so miles and it did the same thing. (keep in mind this whole time I was 100 miles away from my house, it sucked) So what my dad and I thought was after you shut it off wait five minutes and it would cool off, we were wrong. (now this is just a hypothesis) It wasn't that it needed to cool off, the AW4, from what I know, is an electronic transmission. So everytime I shut the car off it would reset something and then I'd have torque for another few miles. Once again thats just my guess but what we eventually did was when we were driving at 55 and it lost torque we shut if off while on the highway still coasting and then restarted it right away. We made it home by some odd stroke of luck. Another thing is after I shut the car off from driving it makes a horrible noise. The last thing is it's delayed going into gears, and that's all gears. If you can diagnose that'd be great but I'm pretty sure after 210,000 the girl just needs a rebuild.

i wolud make sure you dont have a tps problem, i have seen in the past some inexperienced places replace transmissions, then bring it to the dealership for a bad tps

200,000 + miles anything can be bad though.

yeah i just replaced the tps but didnt adjust it because i didnt know how so i suppose that could have been it but anyway the tranny started smokin so im sure ive overheated her and shes dead by now anyway.

ok good luck, but get the tps checked, if it is out of adjustment, it could cause trans problems, like fooling the computer when it should shift. if you have the resources, it should be set 12-14% at idle

yeah i dont even know where to start on adjusting it but it ran so much better after i put the new one on for like 3 weeks but then the tranny just seemed to crap out. I dont know whats up here but the cash to rebuild a tranny is somethin I dont keep on hand.

Eagle said:

The problem is he has a 1990 XJ, That has a 21-spline output. Anything "low mileage" will be out of a newer vehicle with a 23-spline output.

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Ahhh... good to know! I wasn't aware of that as I don't fool with the autos. So what was the year for the 21/23 spline break?

DON'T waste your money on an AW4 rebuild. It will be at LEAST $1500-2000, probably more than your XJ is worth. You can get a good used one for less than $200. If you want to use a newer one all you need is a newer transfer case too, so the spline problem isn't really a big deal.