Novak bellhousing for converting 05-06 NSG370 to AX15

I agree. Neither are perfect and neither are terrible. NV slightly better ratios except reverse, AX is overall shifts a bit more smoothly and is quieter. Personally given the choice I'd choose the AX simply because it can still be found new and is overall more quiet. Either will get the job done.
One I recall was due to the then existence of a short throw shifter for one and not the other.
 
One I recall was due to the then existence of a short throw shifter for one and not the other.
That's a bit absurd. After personally running a short throw for years I got tired of it and went back to stock. To choose a transmission over that is funny.
 
Honestly on the crawling I doubt you will notice much difference. I think you will feel it more on the street than anything, being able to stretch 1st a bit longer, which I like. Obviously offroad 1st in the NSG would be better for crawling but I don't know that it will really make all that much difference real world. Of course, if you had 5.13 with the AX, then that would help get you back closer to what you have now. But obviously that isn't worth a regear alone, better off changing the tcase for that.

Yeah you'll be fine...4.88 isn't bad with 35's either. It will need a bit more downshifting sometimes but not terrible.

Really what I like about a 6 speed is you have more usable ratios for times like passing. 3rd in a 5 speed is traditionally pretty low so that it's not too far away from 2nd. Problem is, with a regeared Jeep that 3rd gear becomes less usable on the highway for passing. My numbers tell me you'll max out 3rd at around 75 with the 5 speed, which isn't bad, but it means if you wanted to quickly overtake someone, you will need to rev match way up there to get into 3rd and then have to basically take it to redline if you are passing 70-80ish and going around someone at a similar speed. Since you will redline before getting to 80, you'd need to go to 4th which kind of sucks.

On the contrary, the 6 speed has that perfect split between 3 and 4, that you can use 3rd for really good mid range acceleration, and 4th can be that passing gear at the 70-80 range. 4th on the 6 speed wouldn't max out until like 85 on the same tire/gear combo. Really it's all compromises. Real world, the AX is a very good transmission. There are very few times I find myself needing to wind out 3rd for a super hard pass. So it's not really a problem, but on paper the 6 speed is just better at covering all the different scenarios.

I found this chart I put together so I could visualize the difference in ratios. It supports your assertion that the difference in first gear (and even 2nd and OD) is comparatively less significant than how the NSG splits the AX's 3-4 into 3-4-5.

1649042126055.webp


Since buying an AX new means there's no core, I can keep my NSG and rebuild it, then either sell it to recoup some of the expense, or put it back in if I decide I don't like the ratios. Even though that's unlikely, having that as a backup plan gives me some ease about the whole thing.

I also found some info about using a first gear and countershaft to get a 4.3:1 first in an AX15. It's about $600 in new parts (that are discontinued and becoming more and more rare) so I won't be doing that (at least for now) but it's interesting nonetheless. If I had the time and the facilities to do a trans rebuild I would entertain the idea of rebuilding a used AX15 with those parts, but I want to have this done ASAP so I can wheel this summer. It would be great if all the AX15 dealers could say to Aisin hey, we know you made these parts too, can you put those in the AX15 instead?
 
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I found this chart I put together so I could visualize the difference in ratios. It supports your assertion that the difference in first gear (and even 2nd and OD) is comparatively less significant than how the NSG splits the AX's 3-4 into 3-4-5.

View attachment 320530

Since buying an AX new means there's no core, I can keep my NSG and rebuild it, then either sell it to recoup some of the expense, or put it back in if I decide I don't like the ratios. Even though that's unlikely, having that as a backup plan gives me some ease about the whole thing.

I also found some info about using a first gear and countershaft to get a 4.3:1 first in an AX15. It's about $600 in new parts (that are discontinued and becoming more and more rare) so I won't be doing that (at least for now) but it's interesting nonetheless. If I had the time and the facilities to do a trans rebuild I would entertain the idea of rebuilding a used AX15 with those parts, but I want to have this done ASAP so I can wheel this summer. It would be great if all the AX15 dealers could say to Aisin hey, we know you made these parts too, can you put those in the AX15 instead?
Yeah I’ve seen you post that one before. Helpful for sure to visualize the differences. In the AX you feel it going from 3-4 for sure. Not that it’s bad, I mean with a regear 4th works quite well, it’s just when you REALLY need all the help you can get, having 3rd split between a lower and taller version would be better for sure like in the passing situation. But this isn’t a 3 speed manual from 1975 with a carbed engine that features a 4200 rpm redline. You have some wiggle room and are much closer to ideal than you would have been way back when.

Keeping the NSG around a bit is not a bad call. Gives you options just in case. I expect you’ll swap the AX in and won’t really be disappointed at all. Try not to zero in on the points you’re expecting to be worse, or else you might conveniently convince yourself they are worse than they really are.

The 4.3 1st would be neat although maybe a bit awkward with the taller 2.3 ratio 2nd of the 5 speed. It would indeed be cool if they built the trans with two different sets of ratios, one of them having 4.3 and you getting to choose which build set you buy from Aisin.
 
ok, I think I'm sold, and it's not even a hard call now because swapping to an AX15 is actually looking less expensive than sticking with a 6 speed.

On first glance it doesn't seem that way because a NSG370 from High Impact can be had for $1950, free shipping.., still need a clutch kit and a metal TOB; my linkage is noisy so I probably need to replace that pivot ball at a minimum. Then here's the kicker---it doesn't include a shift tower; they expect me to reuse mine. Who the hell wants to spend $2k on a transmission and still run the crap shift tower that is discontinued and has a leaky seal that isn't independently serviceable...so I've gotta buy the B&M right? That sucker is up to $600+ these days, so now I'm actually looking at saving $250ish and still haven't figured any sales tax into the NSG scenario.
 
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The 4.3 1st would be neat although maybe a bit awkward with the taller 2.3 ratio 2nd of the 5 speed. It would indeed be cool if they built the trans with two different sets of ratios, one of them having 4.3 and you getting to choose which build set you buy from Aisin.

it does seem like a big jump. The donor transmission did have all the same ratios as AX15 except for the 4.3 first, but from what I can tell it only came in mid 80s Toyota pickups with a turbocharged 22R, which I'm told is fairly rare by my buddy that has an '86 NA pickup.
 
Not really apples to apples since the components list isn't the same, but the difference looks to be in the bellhousing itself and the lack of taxes on Novak. Wonder how Novak gets away without charging sales tax and what makes AAs bellhousing so much pricier.
I understand you comment about apples to apples. For me, it came down to what each vendor said I need to buy to install their conversation. Bigger difference is that AA said I would need to buy their slave cylinder at $195, not sure why. Shipping was also double. I am not going to ask about the taxes, I did not have to pay them and I ok with that.
 
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I understand you comment about apples to apples. For me, it came down to what each vendor said I need to buy to install their conversation. Bigger difference is that AA said I would need to buy their slave cylinder at $195, not sure why. Shipping was also double. I am not going to ask about the taxes, I did not have to pay them and I ok with that.

I just ordered the bellhousing from AA and it ended up not adding the taxes during final checkout. So it ended up about $570 shipped. I found it for $410 with free shipping on Summit, but Summit doesn't have them in stock and is giving an estimated delivery of end of June. I called AA and she told me they were looking at a mid-May delivery, and they tend to fill their direct-to-customer orders first before the big stuff, so it would be likely that I get it earlier ordering direct. Could be smoke up my skirt but I'd rather get this done earlier in the summer if I can.

I also ordered a Luk clutch kit (from Amazon), which includes a release bearing and a pilot bushing, so I'll have some extra parts, but it was worth getting something I know others have used.

I'll probably end up ordering the transmission from Novak though, because as you point out, shipping is less from Utah than from California.
 
When we got the AA bellhousing, the kit included a new all metal throw-out bearing, ball and clip for the clutch fork, and quite a few other odds and ends that were surprising in quantity and quality. I remember thinking if you had the trans, you wouldn't need much else to do the swap.

Edit- I checked the parts list. Clutch fork, hardware, pivot ball, throw-out bearing, pilot bearing and bushing for the end of the crank.
Novak's version comes with clutch fork, pivot ball, and spring. Pilot bearing was $12.75. I will put in a new clutch set while I am there and that should come with the throw-out bearing.
 
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What is the cost for a complete nsg370 rebuild? I read that one of the shafts needs completely replaced to get rid of the rattle sound? Plus a new shift tower (boot leaks, unavailable seperately), fork assembly, gears...etc
I did get an estimate from High Gear in Memphis. $2000.00 and $200.00 shipping. I am going to spend a little more to move away from the NSG370 (although I still have the one in my JK). I looked at rebuilding the NSG370 and by the time I buy the tools to do it would be about $2000.00.
 
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What is the cost for a complete nsg370 rebuild? I read that one of the shafts needs completely replaced to get rid of the rattle sound? Plus a new shift tower (boot leaks, unavailable seperately), fork assembly, gears...etc

High Impact sells a rebuilt one that is as close to new as it could be for $1950 (plus a refundable $500 core), and free shipping both ways. I have a couple of concerns with that, one being the shift tower. It's not included, so I would have to reuse mine. It's long in the tooth, has a leaky seal (which isn't replaceable separately), and the OEM last I looked is about $500. The improved B&M replacement is $650. So it would cost me an extra $300+ to have an as-new NSG370 vs of a brand new AX15 that many consider to be the best transmission put in a Wrangler.
 
Bumping for you because I am also interested in this swap as reverse is almost no longer usable on the trail.

I'm aware of the bellhousing and what not... What else is required? Will a 97-99 boot fit a 2006 tub, do we need an Ax15 mount bracket or will the nsg370 bracket work? If we need the Ax15 bracket, will it mount to the 03-06 skid/crossmember?
I didn't see this post. In embark with mark's videos, the boots were a struggle. He had a 6 video series on the swap and I think it was video 6 where he fought getting the boot reinstalled.

He used the shifter I believe that AA(?) provided him. Which is basically a cane with a rectangular box with a square opening is welded at the bottom. That gets bolted to the transmission stub with a set screw style of connection. The NSG is very different from that setup. However, he did finally get it to work after fighting with it. The stock AX setup is even more bulky than what he got from AA, but the bulk is at about the same height so you should be able to use either the AA or a stock shifter from eBay with similar results. The boot will be a struggle either way.

The boot is the biggest PITA with the swap as far as I can tell. Jeep changed the console up and the boot mounting pattern for 05-06 I believe which if I'm right, is why the earlier boots aren't just a simple bolt on install. The early boots were all rubber too where the later ones were rubber at the tub and pleather at the console.

@mrblaine, haven't you done this swap at least once? Do you recall what your solution was for the boots?
 
High Impact sells a rebuilt one that is as close to new as it could be for $1950 (plus a refundable $500 core), and free shipping both ways. I have a couple of concerns with that, one being the shift tower. It's not included, so I would have to reuse mine. It's long in the tooth, has a leaky seal (which isn't replaceable separately), and the OEM last I looked is about $500. The improved B&M replacement is $650. So it would cost me an extra $300+ to have an as-new NSG370 vs of a brand new AX15 that many consider to be the best transmission put in a Wrangler.

What exactly is leaking on your shift tower? There shouldn't even be any fluid in the shift tower to start with unless you are basically on your roof.

My shift tower was in excellent condition with around 110K miles on it. No issues reusing it at all.
 
What exactly is leaking on your shift tower? There shouldn't even be any fluid in the shift tower to start with unless you are basically on your roof.

My shift tower was in excellent condition with around 110K miles on it. No issues reusing it at all.

I will admit to not looking very deeply into this. I haven't looked at internals of it at all, I just assumed there would be oil there just like any other shifter, either by splashing or droplets in the air making it's way up there, and every time I have the console off I can see (because the tub boot is trashed) a puddle of oil standing in the valley of the seal, I wipe it out, and it's back again the next time. I replaced the upper seal on my AX15 when I found the inner part completely torn and free floating from the outer part, with a 1/2" wide open space between the shifter and the seal. This one doesn't look that bad, but when I found it the first time I looked into it and given the price tag decided it was something I'd just live with. But if I'm gonna spend $2k on a new transmission, I don't really want to keep living with it.
 
We did it in an 05 so we had to change the floor plate with the boot and the front half of the console to get the spacing correct.

ah, that's good to know. I figured I'd need to the floor plate with the boot, didn't think about needing the console. I like the leather boot more than rubber, I might try to make it work as is. If not I guess a 2003-04 console would work? (after they went from 1 piece to 2, but before the NSG). I don't know if the 2 piece console started in 03 or 00, or in between.
 
We did it in an 05 so we had to change the floor plate with the boot and the front half of the console to get the spacing correct.
Oh, that's plenty easy then. Good to know.

I forgot about the floor plate being able to be swapped like that. Wasn't sure how compatible the consoles were year to year either in the way they attach to the tub.
 
ah, that's good to know. I figured I'd need to the floor plate with the boot, didn't think about needing the console. I like the leather boot more than rubber, I might try to make it work as is. If not I guess a 2003-04 console would work? (after they went from 1 piece to 2, but before the NSG). I don't know if the 2 piece console started in 03 or 00, or in between.
Could you just swap to the early boot design but get a leather early boot from Redline goods or similar to get you the leather you want while keeping the older design for sake of a simple swap?
 
ah, that's good to know. I figured I'd need to the floor plate with the boot, didn't think about needing the console. I like the leather boot more than rubber, I might try to make it work as is. If not I guess a 2003-04 console would work? (after they went from 1 piece to 2, but before the NSG). I don't know if the 2 piece console started in 03 or 00, or in between.
Looking at the parts manual it appears 97-00 consoles were 1 piece, 2001 shows it being 2 piece. Not sure why they decided to change it then vs when they did the 03 interior refresh or the NV swap. But for whatever reason looks like 2 piece consoles became a thing for the 01 model year. so I would think you could get an 01-04 front console half.
 
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ah, that's good to know. I figured I'd need to the floor plate with the boot, didn't think about needing the console. I like the leather boot more than rubber, I might try to make it work as is. If not I guess a 2003-04 console would work? (after they went from 1 piece to 2, but before the NSG). I don't know if the 2 piece console started in 03 or 00, or in between.
All the 2 piece versions before 05 are the same spacing for both the mounting bolt under the bezel (which matches up to the leg on the floor plate) and the location of the hole for the bezel. 05-06 that changed due to the different location of the NSG 370 shifter.

The solved the issue with the 42RLE shifter by making the removeable piece on the console that the shift indicator bezel pops into.
 
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