Wanting to put a new ax15 transmission in

[InTacosWeTrust]

Hello, seeking advice on putting in a new ax15 in my 87. Currently have an ax15, don’t know the year or anything about it, other than I replaced the clutch, master and slave, and oil in it recently. My synchros are going out between 3rd and 4th and when it’s hot, it either binds or grinds or doesn’t want to shift unless I manage to shift into 5th, reverse, 1st or 2nd after multiple shifts to those gears to free it up. Anyways, I’m looking for a new turn key ax15, just need to know where I can buy one ready to go with all the fix’ns on it so I can bolt it on and drive it on. I’ll eventually get around to rebuilding the old one. A neighbor of mine has an extra 4.0 he said he’s gonna give me, so I'm going to rebuild up that motor and the old trans as a project. 

[89 MJ]

I think some people on here have used the Novak one and the Advance Adapters one. I don't recall hearing anything bad about either one. 

 

Going to swap to external slave while you're at it?

[ghetdjc320]

Novak will dril the XJ tcase pattern for you. 

[InTacosWeTrust]

If I can get everything needed, just need a parts list if anyone has one for the transmission and external slave so all I have to do is bolt and go, I’ve looked up and tried to get a list but I don’t know if I’m missing things or over buying, there’s information out here, just hard not to get lost in the sauce while researching 

18 hours ago, 89 MJ said:

I think some people on here have used the Novak one and the Advance Adapters one. I don't recall hearing anything bad about either one. 

 

Going to swap to external slave while you're at it?

 

[89 MJ]

I believe you can buy the external slave kit from one of the companies, maybe even both. That's probably the route I'd go for the same reason you mentioned. 

[InTacosWeTrust]

Would you have an exact parts list of everything I need besides the transmission? Would I need a new transfer case? 

[89 MJ]

Shouldn't need a transfer case. 

 

You'll definitely need the bellhousing, clutch fork, throw out bearing, slave cylinder, master cylinder, and clutch line for sure. Probably more things that I'm not thinking of right now. 

 

I'd look into something like this:

https://www.advanceadapters.com/4993?gad_source=1&gad_campaignid=19546564555&gbraid=0AAAAAD7cfhBqvj96u4j13cQJFlOR4rlF5&gclid=Cj0KCQjw18bEBhCBARIsAKuAFEZJHYG3uV8D148Y5nY8DA_pYdeT7CtFY5_uvGZCFq8TgbckdMdDX7kaAqMPEALw_wcB

[InTacosWeTrust]

1 hour ago, 89 MJ said:

Shouldn't need a transfer case. 

 

You'll definitely need the bellhousing, clutch fork, throw out bearing, slave cylinder, master cylinder, and clutch line for sure. Probably more things that I'm not thinking of right now. 

 

I'd look into something like this:

https://www.advanceadapters.com/4993?gad_source=1&gad_campaignid=19546564555&gbraid=0AAAAAD7cfhBqvj96u4j13cQJFlOR4rlF5&gclid=Cj0KCQjw18bEBhCBARIsAKuAFEZJHYG3uV8D148Y5nY8DA_pYdeT7CtFY5_uvGZCFq8TgbckdMdDX7kaAqMPEALw_wcB

Would I need a new clutch or do you know if the one from AA or Novak comes with one already? I just put in a new master as well, would that not work with the slave from their kit? 
 

AA quoted me this and told me this is all I would need 

[89 MJ]

I can't say for sure whether you'd need the clutch or not. I would doubt that the either one comes with a clutch though. I wish I could be more help, but I went from a Peugeot to an external slave AX-15 and replaced all of the hydraulics and clutch at the same time, so I can't say what exactly actually NEEDS changing for your swap.

 

I'll tag @Htchevyii as he has been through this before. I'll also link the video they did on their channel.

 

[InTacosWeTrust]

44 minutes ago, 89 MJ said:

I can't say for sure whether you'd need the clutch or not. I would doubt that the either one comes with a clutch though. I wish I could be more help, but I went from a Peugeot to an external slave AX-15 and replaced all of the hydraulics and clutch at the same time, so I can't say what exactly actually NEEDS changing for your swap.

 

I'll tag @Htchevyii as he has been through this before. I'll also link the video they did on their channel.

 

Thank you!, so I guess from this video I’m going to buy the Novak ax15 trans from them, buy the AA parts I got quoted, along with a new throw out bearing, flywheel, input shaft seal. If I’m leaving anything out let me know, i figure I would use the same clutch kit and master since I replaced it less than 100 miles ago and the clutch kit is a for a 1992 

 

any recommendations on flywheels? 

[89 MJ]

Did you change flywheels when you did the clutch?

 

If not, I would just get a Luk stock replacement for a 1990 MJ if you have a Renix.

[Htchevyii]

I am and have been running a stock replacement 1988 clutch for 25 years without issues with the AX15. No problems with the internal slave AX15 or the external conversion for me. Flywheel is the factory Renix with the updated pilot bearing.

[JZLAJeep]

On 8/5/2025 at 11:41 AM, InTacosWeTrust said:

any recommendations on flywheels? 

Keep your flywheel and have it resurfaced. Did you have the flywheel resurfaced when you did the clutch 100 miles ago?

[InTacosWeTrust]

On 8/6/2025 at 2:30 PM, JZLAJeep said:

Keep your flywheel and have it resurfaced. Did you have the flywheel resurfaced when you did the clutch 100 miles ago?

I did not, had no idea I needed to or needed to replace or resurface it

[InTacosWeTrust]

On 8/6/2025 at 12:20 AM, Htchevyii said:

I am and have been running a stock replacement 1988 clutch for 25 years without issues with the AX15. No problems with the internal slave AX15 or the external conversion for me. Flywheel is the factory Renix with the updated pilot bearing.

Where do you find that flywheel and updated pilot bearing?

[JZLAJeep]

32 minutes ago, InTacosWeTrust said:

Where do you find that flywheel and updated pilot bearing?

You can take your existing flywheel to a machine shop and ask them to resurface it for you. Cost us about $60 last time. 

 

You can buy the pilot bushing from a 70's CJ that will replace the pilot bearing.

 

I found this old write up here 

 

[Htchevyii]

Yes, the crankshaft has a spot for a smaller pilot bearing in the inner smaller hole or the larger OD one that fits into the outer hole. You need the larger one. I think that I just used a 97 one. Some people have reported a 74 or so Jeep 304 bushing fits too, but I can not verify. If you buy a later model one, you need to get one with the spacer, (see pic).