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-   -   1993 YJ Swap from AX-15 to NSG-370 Possible? (

mcachran 12-09-2012 08:38 PM

1993 YJ Swap from AX-15 to NSG-370 Possible?
I have a 1993 YJ with a AX-15 that has a broken shaft and no 5th gear. Locally, I can get a used NSG-370 out of a 2005 TJ with only 50k miles on it for about $500. I'm wondering if it would be a good swap. I've heard it would be better on the interstate and with MPG, but I might lose a little on the rocks (and I'm okay with that). I've also heard you have to get an updated/relocated CPS, but i'm unsure about the flywheel and clutch and any other details. Please help. How hard do you think this swap will be and what other parts do I need? Also, your opinion, is this a good choice or would it be better to wait for a NV3550 or another AX-15?

mcachran 12-09-2012 09:02 PM

And/or would I be better off with a 98-04 NV3550 and how hard is that to swap into my 1993 in comparison to the NSG-370?

Opihi59 12-09-2012 10:54 PM

As I understand it, the Bellhousing for the NSG370 does not mate up with the 4.2 or 4.0 There are Jeepers who have swapped in the 3550 though, the bolt patterns match up. When Jeep went to a NSG370 they also went to a V6 engine. I don't know of a thread in the FAQ for swapping an AX15 to an NV3550 but here are some other threads that you may find useful. Try searching up some stuff on Google or the advanced search option. The AX15 to NV 3550 is completely doable though.

rckchucker 12-09-2012 11:28 PM

I don't know how to answer your CPS questions, but I do know this. If it is out of a TJ like you said, it will bolt right physically. The 4.0 out of an 05 is the same block as a 93. However. You will probably need to change your pilot bearing. The YJ AX15 has a smaller pilot than the TJ AX15, and I'm assuming Jeep kept the larger pilot tip on the trans input with the successive trannies. I'm also assuming you have an internal slave cylinder. You will have to get a slave cylinder from a TJ that is the external type in order for it to bolt up to the bellhousing. As far as I know, the bellhousing on the nsg370 is integrated, so you cannot just swap bellhousings over.

I don't quite know what you mean by lose in the rocks, but the 6 speed has a lower first gear and a deeper overdrive. you get a bonus on both ends. better crawl ratio and keep the revs lower on the hwy.

With all that said, I would stick with the AX15. People bag on it, but after rebuilding it and beating mine like a red headed step child behind my 5.3, I would say it is the best trans that came behind the 4.0. The YJ my dad had when I was growing up had an AX15 in it. My dad but about 220k on the thing without a rebuild. Just some food for thought.

Opihi59 12-09-2012 11:46 PM

Pilot bearings--your 93 will most likely have a 0.750" input snout. So will the NV3550. Not likely you'll have much of an issue with finding the right pilot. Earlier AX15 had a 0.590 pilot snout.

ssquier92 12-09-2012 11:58 PM

Not sure how the YJ cps is.. but will most likely need modified but not hard to do..

It will bolt right up just depending on the pilot like people have stated..

But the first gear is better for crawling (4.46 i think?) where as your ax15 is somewhere around 3.78.. and nv3550 is 4.01 I think.

The OD you will be turning a little more on the highway actually.. the ax15 and nv3550 are .79 and .78 where the nsg is a .84.. Not much difference, but a difference none the less..

nathanninja 12-10-2012 07:15 AM

AX15 to NV3550 swap isn't too bad. Here's a bunch of info I compiled from when I did mine

Jeepsr4me 12-10-2012 08:07 AM


Originally Posted by Opihi59 (Post 14583007)
As I understand it, the Bellhousing for the NSG370 does not mate up with the 4.2 or 4.0 T

It does work with the 4.0, They came stock in the 05 and up TJs which still had the 4.0.

mcachran 12-10-2012 08:41 AM

Thanks for the feedback everyone. I'm wondering if I should just stick with the AX-15. I'm just disappointed with the AX-15 currently in my Jeep. But it sounds like it would be much easier than a NSG370 swap. Also, I thought the NSG370 would do better on the interstate, but after reading the replys to this thread it looks like the ratio in 6th is slightly worse than the ratio in 5th on the AX-15 and the NV3550.

ssquier92 12-10-2012 08:44 AM

Define "worse" If anything it helps you live with your gearing a little more if you have larger tires and regear. These motors like some revs, everyone thinks lower rpm = better mpg. Fact is lower load = better mpg

mcachran 12-10-2012 08:51 AM

@ssquier92: Good to know. Maybe I just don't understand this enough. I have a great Jeep mechanic. I just need to pick a trans and he will run with it. And I have easy access to a NSG370, but I need to factor in the other costs (clutch, flywheel, pilot bearing, slave cylinder, cps, ect.). Not sure which way to go. AX-15 definitely appears to be much easier at this point, but I'm willing to spend the money if it's worth it.

jserna 12-11-2012 04:23 PM

Get the six speed. It is a nice tranny. I want to swap one into my YJ when i get the mula!

Opihi59 12-11-2012 04:36 PM


Originally Posted by Jeepsr4me (Post 14583902)
It does work with the 4.0, They came stock in the 05 and up TJs which still had the 4.0.

As I have understood it though, they are not the same transmissions. But I really did think that when that trans went into Jeeps, it went with the V6. I do appreciate the information. The bellhousing per Se which is actually a bell combined with the front case, is different if it is mated to the V6 vice mated to the 4.0. We know that the bolt pattern is the same for the 4.0 and the 4.2. So what I am hoping to communicate is that if you are going to put an NSG370 on a 4.0, you have to know if that tranny came off of a 4.0, or if it came off the V6 as they are not the same. Here's a quote from Novak:

The 370 is factory compatible with the Jeep / AMC 4.0L I6 engine, when equipped with the right bellhousing. It is also compatible with the 3.8L V6 when equipped with its matching bellhousing.

So, if the tranny came off a 4.0 you're fine, but I just don't know how to determine what vehicle an NSG370 came off of without taking a serious look at the bolt pattern on the bellhousing. Anybody else know? Pictures on Novak would suggest the length of the bell/front case is different between the 2, and this may be the trick to figuring what it will bolt up to.

mcachran 01-23-2013 05:34 PM

Does anyone know where I can get the pigtail/connector for the backup light sensor on a 2005 or 2006 TJ nsg370? I can't find one anywhere... not even from the dealer. Please help.

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