Questions about AX-15 swap in LJ

Cactus Jim

New Member
Joined
Sep 19, 2020
Messages
7
Location
La Mesa, CA
Hey all, I'm new, please don't beat me up!

Time to buy my next project (5th 4x4, but first Jeep). Plannin the build thoroughly and budgeting all parts before purchasing. (But I'm ready to buy once I find the vehicle and work out compatibility.)

Currently looking at non-Rubicon LJs and wondering if there's any advantage to choosing between '04, '05 and '06 when intending to install an AX15. I've read up on it and see the bellhousings and trannies available from Novak And others, which can be set up to mate with the 231 Tcase. I understand the shift rod will have to be bent, etc.

But what I'm not sure about is the wiring harnesses and control modules and sensors. I've read that the harnesses between the 3 LJ years have differences. I'm wondering if selecting an '05 or '06 LJ with an NSG370 would make for an easier swap than A 42RLE. If it's going to be a hassle in all cases, I may opt for the cleanest, lowest mileage specimen, even if it's got an automatic. Or if a certain year plays nicer with the AX15, I may get picky about the year in my search. Not sure how different the hole is in the floor between the auto and manual LJs. I'd prefer a nice looking fitment if possible. My other worry is passing CA emissions after the swap.

I've never pulled a tranny this new (last one was on a 79 Dodge), and I'm confused about all the sensors and modules and harnesses.

if anybody has any tips that would be great. I've got axle and driveshaft questions too but I'll start with the tranny.

thanks
 
Swapping between a manual transmission and a manual transmission will be easier than going from a manual to automatic or automatic to a manual.
The computer needs to know what transmission (auto or manual) and there is a transmission control module involved with the automatic transmission.
The swapping of transmissions will not impact your SMOG certification.
 
  • Like
Reactions: Chris
Thanks! I'll try to write out a list of all the connections then and make sure I've covered it all. Some of the cleaner, unmodded LJs in my search radius are auto, but I'll avoid those.

I read that the crank position sensor will work with the bell housing from Advance Adaptors and I need an '05 or '06 flywheel, and the speed signal is coming from the tcase, so that stays.

I know the swap has been done before so fingers crossed I can figure it out.
 
The flywheel for the 05-06 with the 6 speed manual transmission is different than the earlier model year flywheels.
The 05-06 flywheel has two points for the CKPS (Hall Effect sensor) to read and the 97-04 has three points to read.
 
Last edited:
Why don't you buy a manual LJ and not have to deal with this swap? Is it really worth it to buy an LJ with a working trans and swap it to a different manual trans?

I had a different swap done: 06 LJ manual, swapped to an auto from an 05. Easier swap because all the parts were swapped. Though you're not likely to find someone that wants to trade + different year models, etc.

I'm obviously not a fan of manual trans, but I have to admit the 6 speed manual was much more suited for highway driving. Especially driving up a mountain. I just hated it when wheeling.
 
Why don't you buy a manual LJ and not have to deal with this swap? Is it really worth it to buy an LJ with a working trans and swap it to a different manual trans?

I had a different swap done: 06 LJ manual, swapped to an auto from an 05. Easier swap because all the parts were swapped. Though you're not likely to find someone that wants to trade + different year models, etc.

I'm obviously not a fan of manual trans, but I have to admit the 6 speed manual was much more suited for highway driving. Especially driving up a mountain. I just hated it when wheeling.

Yeah I'm not trying to go from auto to manual, especially after confirming it's a pain, I'm just trying build a more "bulletproof" rig by replacing a NGS370 with a zero miles AX15. (Based only on owner complaints on the interwebs) Admittedly that's really something I should consider once the original trans actually starts to fail. The issues I've read about, slipping out of reverse, slipping out of 1st, making noises aren't things that would immediately strand me. I just came across an 06 with a claimed 50k miles, waiting to hear back. It would probably go a long way before it started acting up.

I generally drive 2 to 7 hours on the freeway to get to deserts in CA and AZ, and then I camp and drive around for a few days on mostly flat trails with sand beds and loose rocks. But there's a few trails where I can definitely see manual being annoying, and I did want to take it to Broken Arrow in Sedona, which is slightly sketchy in parts and I'd probably want an auto there. I'm kind of guessing since I haven't owned this configuration yet. But I do want a zippy feeling fun vehicle for cruising around the desert and getting to the desert.

First step I just need to get the Jeep. Might be a good idea, before I start ordering transmissions.
 
I drove the 6 speed for around 15K miles. Absolutely no problems, no popping out of gear, etc. No complaints at all on the street or highway. I just didn't like it on the trail and will never by a manual 4X4 again.

Find a manual LJ and see if you have any problems. Then think about swapping the trans. I didn't do the work, but know it's a giant pain in the ass (unless that sounds fun to you). If you buy an LJ and the trans is trash, I'd still consider fixing it or replacing with the same oem trans.
 
Just drive the NSG370 until it goes. I have a TJ with the NSG370 and a TJ with the NV3550. I like the NSG370 a lot more 👍

If my transmission ever goes, I will replace it with an AX-15, simply because they are cheaper than the others, readily available, and a very good transmission. I'm told I'll need an adapter and a few other minor things, but that's not a big deal.

If I could get a new NSG370 for the same price as a new AX-15, I'd go with the NSG370. However, if you've seen the price of a new NSG370 (if you can even find one), it's something like $2700, whereas a new AX-15 is $1600.
 
  • Like
Reactions: L J