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Old July 2nd, 2015, 16:03
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kastein kastein is offline
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Everything you ever wanted to know about the AX15 (and some about the AX5)

So. Since the "Everything you ever wanted to know about the AW4" thread went pretty well, here goes the next installment, everything you ever wanted to know about the AX15 (and all the things you didn't want to know about the AX5!)

There are many AX15s out there, in a variety of years. I know for a fact they're used in:
- 1989.5-1999 XJs, 4.0L
- 1989.5-1992 MJs, 4.0L
- 1989.5-1995 YJs, 4.0L
- 1997-199? TJs, 4.0L
- unknown year range Dakotas, 4 (both K-car 2.5L and AMC 2.5L - more on this later) and 6 (3.9L V6 - basically a 5.2L V8 minus two cylinders) cylinder.
- unknown year range Toyota 4runners, pickups, and Supras. They are known as the R150 series transmission in these vehicles.
- A large variety of other vehicles I won't cover here. Lots of GM stuff, surprisingly.

Torque rating is rumored to be approximately 300 foot pounds. Which is the same as the ratings on the NV3550 and NV3500 (often confused for each other) so careful about letting people tell you an NV3550 is stronger than an AX15. Jeep/Dodge switched to NVG manual gearboxes in the 1998-2000 timeframe, depending on which vehicle you're talking about. My suspicion is that it was because they were by then only ordering AW4s, AX15s, and AX5s from Aisin, knew XJ AW4/AX15/AX5 orders were coming to an end soon, and wanted to consolidate contracts with another supplier that was already producing 100% of their transfer cases and many of their fullsize Dodge manual transmissions (all Dodge 1500s-3500s use either an NV3500 or NV4500) to save money, but I have no proof for that statement (aside from the NV3550 being almost bolt-in into the spot an AX15 comes out of, which is abnormal unless it was designed as a replacement) so take it with a grain of salt.

Basically, this is a very common gearbox. People think they're hard to find, but they aren't. The only differences are in the bellhousing, input bearing retainer, input shaft, tailhousing, and output bearing retainer, aside from some inconsequential stuff. The 4.0L bellhousings are exactly as hard to find as you think they are, since they only came in jeeps, but if you just need a replacement transmission since you slagged yours and can swap your bellhousing over to the new one... they are not hard at all. Walk through the Dakota section of your local yard and at least one of the 4/6 cylinder ones will probably have an AX15 in it.

For instance, I used an XJ/YJ/TJ/ZJ/MJ 4.0L to AX15 bellhousing along with a 1997 Dakota 3.9L AX15 and dropped it straight into my 1998 XJ when I swapped it to 5 speed.

From now on, to save significant confusion, just assume I'm speaking of Chrysler/Jeep/Dodge family AX15s, not the Toyota ones or anything else.

There are a few parts that have year splits:
- input shaft pilot tip diameter: 1991 and earlier vehicles use a roughly 15mm pilot tip. 1992 and later vehicles use a roughly 19mm pilot tip.
- slave cylinder style: 1993 and earlier vehicles use an internal slave. 1994 and later use an external slave. The parts affected by this change are the bellhousing, clutch release hardware (fork, pivot ball, throwout bearing, slave cylinder, retention clips), and input bearing retainer / throwout bearing quill. You can swap that all over if you want.

And a few parts that have vehicle splits:
- The tailhousing/rear case half. XJs, MJs, ZJs, and Dakotas share a rear case half. YJs and (I believe) TJs share a different one - still looking to verify this. The only significant difference is the clocking angle of the transfer case mounting bolt pattern; I've put an XJ AX15 into a YJ without issue other than floor/crossmember clearance. This is 4wd specific, I'm not going to cover 2wd units as I don't know enough about them to make sure my info is correct.
- the shift lever and turret. YJs, TJs, and Dakotas have a tall one to accomodate the higher seating position relative to the transmission, XJs, MJs, and ZJs have a short one. You must keep the lever and turret from the same side of this split but can swap back and forth across it otherwise. For instance I have the Dakota shift turret and lever in my 1998 XJ and love it, it puts the shifter a couple inches from the steering wheel in first gear but keeps the shift throw about as long as it is on a stock XJ shifter. If you wanted to, you could cut a Dakota one down to make an XJ short shifter, too.
- the bellhousing. This is different depending on what engine the transmission came behind. Available bellhousings include the 2.5L K-car (Dakota 4cyl 95-, pretty useless to us), 2.5L Jeep (Dakota 96+ 2.5L poverty spec vehicles had an AX15 and an AMC/Jeep 2.5L engine - this is great if you're tired of blowing up AX5s, use this bellhousing and an AX15), 3.9L Dodge V6 (V6 Dakotas got this bellhousing), and 4.0L Jeep. You can use whatever you want from this list to connect an AX15 to your engine of choice, just be aware that you may have to play games with pilot bearings, clutch discs, throwout bearings, etc to make it all work.

All 4wd AX15s have a 23 spline output shaft. All have the same ratio set, as far as I'm aware.

Transmission internal info, "gotchas" for home rebuilders, etc:
- First and second gears use the same synchro ring.
- Third, fourth, and fifth use SIMILAR rings. Two will match, one will not. It will have a different angle on the dog teeth. When you reassemble your transmission, you MUST make sure that the new stop rings are installed such that the synchro with the different tooth angle matches up with the synchro sleeve that has a matching tooth angle, otherwise it won't shift right.
- It's easy to accidentally put the fifth gear synchro sleeve on backwards. Don't do this! It will NOT shift right. One end of the splines on the inside of the sleeve has dog teeth ground into it, the other is flat tipped. Make sure the dog tooth end faces AWAY from the midplate, at the fifth gear synchro + gears.

All years (that I am aware of) use the same input and output seals, so I'm not going to go into detail on that. You can buy em wherever you want.


Now, on to the AX5. If the Peugeot BA-10/5 is the dana 35 of transmissions, this is the 27 spline 8.25. It'll work, but be nice to it so it stays that way. Internally they look very similar to an AX15, but nothing is quite as strong and in general these are intended for much lighter duty, thus why they were used behind 4-cyl engines. I've seen a LOT of them blow up second or third gear. In fact I collected enough broken ones at one point that I got bored and put together a spare one entirely out of salvaged parts from a total of three donor transmissions. They have a different bolt pattern where the bellhousing bolts on, and all are 21 spline. Pilot tip is 0.590". There is a lot of picky stuff and a lot of year splits you need to take into account when choosing a donor for the bellhousing and transmission for simplicity of an AX5-to-AX15 swap, but all of them will work with enough work.

Note that you can play all sorts of games and do all sorts of interesting swaps with this info, especially the 4cyl and 6cyl Dakota bellhousing info. Most of them are a bad idea and will probably result in the death of your AX15, but let your mind run wild. For example, since the 4cyl Dakota bellhousing pattern matches an AMC 2.5L (which was designed to drop into an assembly line that was intended to put 151ci GM Iron Dukes and 2.8L GM V6s in things, and thus has a 60 degree GM V6 pattern) to an AX15, you could theoretically use it to put a 325hp late model Impala SS LS4 V8 in front of an AX15, or with a few holes redrilled, a 32 valve Cadillac Northstar. I wouldn't recommend this though as you'll probably blow the trans up in a hurry. You could also use this info to put a supercharged GM 3800 V6 in, which is a better idea (260hp/280ft-lb is not unmanageable for an AX15, and they're more compact than a 4.0 rather than less.) The 3.9L V6 bellhousing only fits Mopar family engines, but it enables things like a 2.8L Liberty CRD to AX15 mating, or a 5.2L/5.9L Magnum V8 to AX15 mating (also a bad idea, because a 5.2 probably isn't worth the complexity of this swap and a 5.9 will nuke an AX15 fast.)

That's about all I can think of, these are far simpler than the AW4 (and have far fewer differences year over year and vehicle to vehicle) and the changes are far easier to deal with since none of them involve wiring. I may do a teardown/rebuilder picture-by-picture guide if I get around to rebuilding my spare unit sometime soon. They're not overly complicated transmissions and anyone who can install an SYE successfully can probably rebuild one in anywhere from six hours to two days depending on the tools they have available and how much cleaning is done during the teardown. Rebuild kits are available for anywhere from $150 to $500 depending on where you buy it and who made (or repackaged) it.

Something I missed? Novak Conversions' page may cover it, if not, ask here and I'll explain if I can.
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Last edited by kastein; September 29th, 2015 at 15:17.
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  #2  
Old July 2nd, 2015, 19:23
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Anak Anak is offline
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Re: Everything you ever wanted to know about the AX15 (and some about the AX5)

Very cool.

If you do ever get around to them I would love to see pics and directions for tearing into one.

I am especially curious about the issue regarding synchros being similar. My AX15 shifts lousy going into 1st, and not particularly well going into second. It is the worst shifting manual I have ever driven, including the Saginaw 3 speed in my '68 Camaro and the SM465 in my dad's pickup. Its like gravel compared to a World Class T5, or even the NV4500 behind my Cummins. I can't believe it is working correctly.

The worst part of it, the previous owner supposedly had it rebuilt by a local shop that should know something about Jeep gearboxes: Border Parts. I do not doubt that the transmission has been out of the vehicle. It has a relatively clean coat of gray paint on it. It is cleaner than anything else under the vehicle. Something has been done to it, but I suspect not done entirely correctly.

I also have to wonder how much noise it should make going into reverse. About half the time it sounds as if I have not bothered to put in the clutch. Is that typical?

This is one of those things where I would like to know what I would be getting into if I were to try to open this thing up and deal with it myself.
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Old July 3rd, 2015, 05:59
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kastein kastein is offline
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Re: Everything you ever wanted to know about the AX15 (and some about the AX5)

Reverse is non synchronized and typically gets pretty blunted by age, use, and abuse so yeah it will make some noise on most jeeps.

The right fluid can help a lot with shifting, I personally run Mobil1 10w30 full synthetic in my AX15s. I have also heard that Royal Purple gear oil, redline, pennzoil synchromesh, and a few others are good but have not tried them myself. As long as you use a motor oil or a GL3/5 that specifically lists yellow metal compatibility it at least will not actively harm the AX15.

I will see about doing a teardown and rebuild soon. Been looking for an excuse to buy a sandblaster anyways...
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My yard looks like Sanford & Sons.
Please do not PM me about the AW4 info thread unless you have a truly unique question that is not covered by it or info to add. I do not respond to questions answered by the thread.
Definitely do not hunt down my phone number at 3AM, text me about it, and then threaten violence when I am not helpful. It will not get you what you want.
CTeunuch: Sometimes I really wonder if this sport makes you insane, or it just attracts the mentally unstable.
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Old July 3rd, 2015, 07:05
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Re: Everything you ever wanted to know about the AX15 (and some about the AX5)

Thank you for the explanation on the reverse gears.

I did look into fluid and decided to try the Redline MT-90. Filled it through the shift tower to get an extra half-quart or so in there (IIRC). No improvement for my situation.
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Old September 7th, 2015, 09:22
BajaXJ92 BajaXJ92 is offline
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Re: Everything you ever wanted to know about the AX15 (and some about the AX5)

Here's my questions:

I was removing my shift tower from inside the jeep, and ended up breaking the round silver retainer that's just to the right of the black rubber boot. Does Jeep sell this piece?

Also, I have a 1990 YJ with an AX-5 in it. Will the shifter in that bolt into the AX-15 in my '94 XJ?

Thanks for the help fellas!

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Old September 8th, 2015, 10:16
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gradon gradon is offline
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Everything you ever wanted to know about the AX15 (and some about the AX5)

Great info. I'm on my fourth 2dr 2wd manual 4.0l xj over 21 years and plan on always having a manual xj. About the only thing I haven't done to an xj over those 21 years is open up the ax15. I do have a spare rebuilt one that had it's input shaft bearing trashed during a high speed rollover, so might dig in it eventually.
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Old September 9th, 2015, 13:57
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s14unimog s14unimog is offline
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Re: Everything you ever wanted to know about the AX15 (and some about the AX5)

A lot of good information in here - allow me to add some pictures. I've had a lot of experience with my AX15 (factory installed from my 97 XJ) over the years.

Although its a really simple/strong little 5-box, I've had a couple reoccurring issues; I wonder if you've run across this before. Back when I originally got my XJ, it soon developed an issue shifting into 3rd. Come to find out, the 3rd gear side of the 3-4 fork wore down from what I could only discern was the fault of the previous owner running the trans dry. He did that after plugging the weep hole (I guess he got tired of the leak) and all of the fluid migrating to the transfer case. Either it be, I pulled the trans, rebuild it (new TransStar syncros and bearings) and threw it back together. All to figure out the problem was no different. In my hast I looked right over the heat discolored fork. Long story short, the trans came back down, swapped the fork and I was off shifting smooth. 8-9 months later, it came back. This time being prepared, and getting quite good at this, I pulled it down and again, swapped the fork and had it back together before finishing my 12-pack. 6 months later.......you guessed it, lost 3rd again. This time, I changed the 3-4 collar and fork. I'm a month down the road at this point - here's hoping.

Ever ran into this? My hope is that the mild imperfections in the collar were slowly wearing the fork down, so my hope is that I've got it all fixed now.



a good reason you can't catch 3rd....



my dirty AX15 (Hurst turret)



shifter location through the cabin



Bearings



Seals



Syncros


Last edited by s14unimog; September 9th, 2015 at 14:01.
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Old September 29th, 2015, 15:22
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kastein kastein is offline
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Re: Everything you ever wanted to know about the AX15 (and some about the AX5)

Looks good and I would assume that you are right about the damaged surface on the synchro sleeve/collar eating up the new forks, too.

To the guy with the shifter retention clip question - yes, as far as I know an AX5 clip will fit your AX15 fine. A friend is running one like that with no complaints. I haven't cross referenced it in the parts catalog but he has 25k miles on the YJ AX5 shift lever and retention clip in a Dakota/YJ/TJ AX15 shift turret on top of an XJ AX15, so I assume it is compatible. I drove it and it shifted just like they all do.
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My yard looks like Sanford & Sons.
Please do not PM me about the AW4 info thread unless you have a truly unique question that is not covered by it or info to add. I do not respond to questions answered by the thread.
Definitely do not hunt down my phone number at 3AM, text me about it, and then threaten violence when I am not helpful. It will not get you what you want.
CTeunuch: Sometimes I really wonder if this sport makes you insane, or it just attracts the mentally unstable.
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Old May 23rd, 2016, 21:40
puntforloss puntforloss is offline
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Re: Everything you ever wanted to know about the AX15 (and some about the AX5)

Thanks for the info! I had a nightmare with a French-5 on a CJ7 (replaced with t18) and I had some fear about buying a 97 XJ with a AX15 before learning the difference here. I would much rather find a stockish xj with a ax15. But, they don't come arround every day.
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Old May 24th, 2016, 07:02
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87manche 87manche is offline
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Re: Everything you ever wanted to know about the AX15 (and some about the AX5)

Quote:
Originally Posted by kastein View Post
Reverse is non synchronized and typically gets pretty blunted by age, use, and abuse so yeah it will make some noise on most jeeps.

The right fluid can help a lot with shifting, I personally run Mobil1 10w30 full synthetic in my AX15s. I have also heard that Royal Purple gear oil, redline, pennzoil synchromesh, and a few others are good but have not tried them myself. As long as you use a motor oil or a GL3/5 that specifically lists yellow metal compatibility it at least will not actively harm the AX15.

I will see about doing a teardown and rebuild soon. Been looking for an excuse to buy a sandblaster anyways...
MT90 is the best I ever used.
Syncromesh works fine, but still gets stiff in the winter.
Recommended gear oil makes it feel like the shifter is stuck in concrete in the winter.
Never tried motor oil.
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Old May 24th, 2016, 08:34
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kastein kastein is offline
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Re: Everything you ever wanted to know about the AX15 (and some about the AX5)

At this point I've put nearly a hundred thousand miles on a handful of AX15s with Mobil1 10W30 in them. Perfectly happy with it and will continue to run it.
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Please do not PM me about the AW4 info thread unless you have a truly unique question that is not covered by it or info to add. I do not respond to questions answered by the thread.
Definitely do not hunt down my phone number at 3AM, text me about it, and then threaten violence when I am not helpful. It will not get you what you want.
CTeunuch: Sometimes I really wonder if this sport makes you insane, or it just attracts the mentally unstable.
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  #12  
Old May 24th, 2016, 17:43
puntforloss puntforloss is offline
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Re: Everything you ever wanted to know about the AX15 (and some about the AX5)

Quote:
Originally Posted by kastein View Post
At this point I've put nearly a hundred thousand miles on a handful of AX15s with Mobil1 10W30 in them. Perfectly happy with it and will continue to run it.
Have you ever considered using 5w-30?
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Old May 25th, 2016, 05:21
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kastein kastein is offline
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Re: Everything you ever wanted to know about the AX15 (and some about the AX5)

Not really. People recommended 10W30 and it worked for me so I haven't bothered to experiment.
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My yard looks like Sanford & Sons.
Please do not PM me about the AW4 info thread unless you have a truly unique question that is not covered by it or info to add. I do not respond to questions answered by the thread.
Definitely do not hunt down my phone number at 3AM, text me about it, and then threaten violence when I am not helpful. It will not get you what you want.
CTeunuch: Sometimes I really wonder if this sport makes you insane, or it just attracts the mentally unstable.
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Old June 17th, 2016, 19:48
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macidgit macidgit is offline
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Question Parts Need Going from AX5 >> to >> AX15 ??

I have a 1997 AX5 equipped 4.0 XJ with NP231 xfer case. The AX5 has developed the problem of not staying in 1st gear.

The transmission shop won't rebuild it, and wants $1500 to swap out with low-miles used AX5.

I'd prefer to replace the AX5 with an AX15 on my own.

From what I can tell in this thread, I would need:
  1. Used AX15
  2. AX15 compatible bellhousing
  3. Appropriately-sized pilot bearing
  4. New clutch, pressure plate and throwout bearing
Used AX15

Does anyone know if there are any other other unique-to-AX15 parts I would need?
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Old June 18th, 2016, 14:24
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kastein kastein is offline
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Re: Everything you ever wanted to know about the AX15 (and some about the AX5)

The factory never put an AX5 behind a 4.0, so you are simply swapping an AX15 in in place of a different AX15. Any 94-99 AX15 from an XJ or Dakota will fit if you swap the bellhousing and shift lever+turret (on a dakota ax15) or simply drop it in (xj donor). You can go as early as 92 if you don't mind swapping the input bearing retainer and as early as 89.5 if you don't mind swapping the pilot bearing to a 15mm bore one.
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