How to AX15 swap for my T18, any advice?

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PlumCrazyChris
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How to AX15 swap for my T18, any advice?

Post by PlumCrazyChris »

I'd really like to swap a AX15 5spd in place of my stock 360/T18 with granny low in my 79 Cherokee. I see that its possible and would be a good match, according to the Novak site.

My question is, what are sources for the correct AX15, and what is required to change on my current setup? Are there better versions of the AX15 that I should look for? Any years betters than others?

Would I need to shorten/lengthen driveshafts?

Anyone have any experience with this, or thoughts on how to?

Thanks!
PlumCrazyChris
1990 Grand Wagoneer (new project)
1983 Cherokee Limited (sold)
1979 Cherokee (sold)
Round Rock, TX
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Yeller
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Re: How to AX15 swap for my T18, any advice?

Post by Yeller »

No experience with FSJ’s with them. Have done a few swaps with them. For what you can buy a new one for it would have to almost be free to warrant gambling on a used one. Any 6 bolt round pattern 23 spline input transfer case will bolt up. Not sure what bellhousing you would need, just haven’t researched. I’m sure driveshafts would need to be modified.
The bus I ride is so short it is a yellow Smart Car full of squirrels, monkeys and clowns.

1970 J2500 Resto Mod
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rocklaurence
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Re: How to AX15 swap for my T18, any advice?

Post by rocklaurence »

I have one in my '80 Chief. I used a low profile MC with a remote bowl from Summit. The AMC bell housing bolts right up, get the external TO bearing setup and Id include the Jeep NP231/241 instead of trying to use the NP208/229. Buy the newest AX15 you can because they'll have the upgrades and there were only a few early years that had the smaller output shaft. Plus, the AX15 is very close to being the same length as the old manuals with the V8 spacer [the block between the bell housing and trans]
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Stuka
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Re: How to AX15 swap for my T18, any advice?

Post by Stuka »

Its worth noting that your stock t-case (D20) won't work with an AX-15. And every single t-case that came behind an AX-15 is driver side drop. Your front axle is passenger side drop.

There are t-cases that will work, but they are less common. A Jeep D300 (from 80's CJ5 or CJ7) can be put behind an AX-15. It does require a spacer between the trans and t-case. Novak makes a clocking ring that will act as the spacer, and let you angle the t-case how you need.
2017 JKU Rubicon
Pevious Jeeps: 1981 J10, 1975 Cherokee, 2008 JK, 2005 KJ, 1989 XJ
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Yeller
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Re: How to AX15 swap for my T18, any advice?

Post by Yeller »

The Dana 20 will not just bolt up, but Novak and I believe Advance Adapters have an adapter, they may even sell the same one, I've seen them share parts in the past.

https://www.novak-adapt.com/catalog/ada ... o/kit-152/
The bus I ride is so short it is a yellow Smart Car full of squirrels, monkeys and clowns.

1970 J2500 Resto Mod
https://www.fsjnetwork.com/forum/viewt ... 12&t=21395

1974 Bronco “Broncno”
https://classicbroncos.com/forums/threa ... st-3411909
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Stuka
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Re: How to AX15 swap for my T18, any advice?

Post by Stuka »

Yeller wrote: Wed May 18, 2022 8:03 am The Dana 20 will not just bolt up, but Novak and I believe Advance Adapters have an adapter, they may even sell the same one, I've seen them share parts in the past.

https://www.novak-adapt.com/catalog/ada ... o/kit-152/
True. But for $700 (price of the adapter), you can buy a used D300 (though better condition ones are $1000). The clocking ring is only $50. If the D20 had a fresh rebuild, the adapter may make sense. Drive shafts would bolt back up (though they may be the wrong length after the swap).

If I had a choice between a D20 and a D300, the 300 is a better t-case. Better low range, much stronger rear output. But slightly higher cost, and may require drive shaft changes.
2017 JKU Rubicon
Pevious Jeeps: 1981 J10, 1975 Cherokee, 2008 JK, 2005 KJ, 1989 XJ
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Yeller
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Re: How to AX15 swap for my T18, any advice?

Post by Yeller »

Just showing options, all are valid points. Given the choice a 300 would be my option as well. There is also the Atlas option, it just isn’t very budget friendly.
The bus I ride is so short it is a yellow Smart Car full of squirrels, monkeys and clowns.

1970 J2500 Resto Mod
https://www.fsjnetwork.com/forum/viewt ... 12&t=21395

1974 Bronco “Broncno”
https://classicbroncos.com/forums/threa ... st-3411909
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tgreese
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Re: How to AX15 swap for my T18, any advice?

Post by tgreese »

What about the NP241C? That can be passenger drop. I've read a lot about it but don't have any first-hand experience. It's chain driven, unlike the 300. With some scrounging, you might be able to go with that for a lot less than the 300.

JMO - these medium-duty 5-speeds (including the NVG3550) are something of a downgrade to the T-18 combo. What do you imagine you are going to gain from this swap? Also my opinion, you'd be better off to go with a multiport SBC and overdrive automatic than the XJ/TJ manual transmission. Donors for these manual transmissions are not cheap, and far from plentiful. Anything that runs and drives in an XJ or TJ will have considerable market value. Sell the truck to somebody that wants it for what it is, and build up an automatic truck. They are way more plentiful than the manual transmission models.
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Yeller
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Re: How to AX15 swap for my T18, any advice?

Post by Yeller »

241C is only an option if you change the input shaft to a 23 spline unit. Passenger drop units though are getting pricy, I need a case for mine, it has a crack. From what I'm finding for parts cost, if I pay myself labor to fix it after buying parts, its less expensive to buy an Atlas..... Which unless I find a deal, is going to be what happens.

If you like driving a manual, the AX15 is an upgrade in everyway to a T18 except compound 1st gear and reverse for crawling and maybe ultimate torque input, all of which a 360 isn't getting to without some major mods. For most folks even wheeling an AX15 is plenty low. I came close to going this route on my J truck because I like driving a manual. The AX15 shifts very smooth and fast compared to the dump truck T18.
The bus I ride is so short it is a yellow Smart Car full of squirrels, monkeys and clowns.

1970 J2500 Resto Mod
https://www.fsjnetwork.com/forum/viewt ... 12&t=21395

1974 Bronco “Broncno”
https://classicbroncos.com/forums/threa ... st-3411909

Topic author
PlumCrazyChris
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Re: How to AX15 swap for my T18, any advice?

Post by PlumCrazyChris »

Such great input! Thanks guys for your thoughtful responses! I guess I need to put pencil to paper and get these options/requirements summarized and figure out a plan. I don't have much experience with Jeep manual trans, or manual transmissions in general, so I'll have to ruminate some on this, start scrounging parts, and come up with a plan. I'm sure I'll be revisiting this thread, and reaching out for thoughts in the future on this. Now I need to get a new A4LD in my son's Bronco II first... it just went south. AAMCO tells me they can't even rebuild them anymore....
PlumCrazyChris
1990 Grand Wagoneer (new project)
1983 Cherokee Limited (sold)
1979 Cherokee (sold)
Round Rock, TX
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devildog80
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Re: How to AX15 swap for my T18, any advice?

Post by devildog80 »

Can't or won't?

We do find that with our Jeep components too, and why many of us dive in and just do them ourselves.

Good luck with the Bronco :)
'81 CJ5 Base, 258 I6, MC2100, T176 4 spd, 300 TC, D30 Front NT, 3.31, 2-Piece AMC 20 rear NT, 3.31, 4" high arc spring lift
'84 Grand Wagoneer, 401 V8 (.030 over), MC2150 HA Comp, 727 auto, Selec-trac NP229, AMC 20 REAR - D44 FRONT - WT 3.31, 4" high arc spring lift
Rather be driving, than waiting to be modified
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Yeller
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Re: How to AX15 swap for my T18, any advice?

Post by Yeller »

devildog80 wrote: Fri May 20, 2022 11:16 am Can't or won't?

We do find that with our Jeep components too, and why many of us dive in and just do them ourselves.

Good luck with the Bronco :)
Exactly what went through my mind, 25+ years ago I used to do 3 or 4 of them a week. I'd ask around, unless it is universally not supported for parts someone will rebuild it.
The bus I ride is so short it is a yellow Smart Car full of squirrels, monkeys and clowns.

1970 J2500 Resto Mod
https://www.fsjnetwork.com/forum/viewt ... 12&t=21395

1974 Bronco “Broncno”
https://classicbroncos.com/forums/threa ... st-3411909
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Stuka
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Re: How to AX15 swap for my T18, any advice?

Post by Stuka »

PlumCrazyChris wrote: Fri May 20, 2022 10:13 am AAMCO tells me they can't even rebuild them anymore....
Find a transmission shop that isn't a nationwide chain. AAMCO tends to only only want to rebuild/replace late model stuff.
2017 JKU Rubicon
Pevious Jeeps: 1981 J10, 1975 Cherokee, 2008 JK, 2005 KJ, 1989 XJ
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