Jeep Enthusiast Forums banner

2.5+AX15 swap complete!

92K views 59 replies 31 participants last post by  fishadventure 
#1 ·
Well, I'm finally finished installing my AX15 into my 4 banger jeep.
It actually went WAY smoother than expected.
I still need to have my rear shaft cut and balanced, so I drove home from my dads shop in front wheel drive (love the SYE already!) about 45 miles going 45mph to be safe...front is locked up and acts squirelly on the highway.
I was asked many time to do a write up on this, but I was just trying to get it done.
I don't have anything for pictures, but would be happy to answer any questions about the install, and do a set of instructions on this. I will start by assuming the old AX5 is out. I am also assuming a swap to external slave.

Parts list:
AX15 torque arm bracket (if not included with tranny (dealer))
AX15 transmission
AX15 shifter
AX15/NP231 TC shifter (or mod AX5/NP231 TC shifter)
'96 Dakota bellhousing
Pilot bushing/bearing (Novak 716167 http://advanceadapters.com/index.php?p=view_product&product_id=2506)
9" 10 spline clutch disc (I used NAPA# RCF584)
Clutch alignment tool
GOOD snap ring pliers

If converting from internal to external slave:
'94 YJ: clutch fork, clutch fork retainer clip, front bearing retainer, throw out bearing, slave cylinder.

I used a '92 YJ AX15 and NP231. This was an internal slave, so I sourced an external slave front bearing retainer, clutch fork, clutch fork retainer spring clip and Dakota bellhousing.
Install the pilot bushing in the flywheel after soaking it in 20/50 oil for 24 hours.
I removed old seal from the external front bearing retainer, and installed new seal.
I installed the external slave front bearing retainer. Installed the bearing into the clutch fork, and mounted on the tranny.
I used a '94 YJ slave cylinder, and installed it on my factory line/clutch master cylinder. I did NOT have to fabricate a longer push rod. I bled the slave according to the instructions, and it works great.
The Dakota bell housing was bolted up and torqued to the AX15.

While the transmission was out, I installed an SYE. This was actually very simple, but I recommend a GOOD snap ring tool! Mine was Chinese junk, and I needed my dad to help me remove and install the 4 or so rings during the process.

I also drained the TC and AX15. I "flushed" the AX15 with fresh oil, and drained it again.

I used the factory AX5 tranny mount because they are the same as the AX15. My AX15 did not include the factory torque arm bracket so I ordered one through the dealership ($65).
My skid had elongated holes that did not require notching for the longer transmission (see below).

The new bell housing and the AX15 add about 3 inches to the overall length of the drivetrain, so expect to notch the floor pan for the TC shifter. I could not find a factory AX15 shifter, so I bought a B&M on sale ($160). The transmission shifter clears the floor pan just fine.
The TC shifter needs a notch in the floor about 1.5" wide by 2" long.
The AX5 TC shifter is not a direct bolt on. Expect to elongate the top two bolt holes for the AX15 shifter bolt patter, and I also needed to elongate the lower bolt hole. The AX5 TC shifter and linkage now works perfectly.

I reused my factory flywheel and pressure plate. Using a clutch alignment tool, I quickly had the new clutch installed and the pressure plate back on.
A transmission jack is your friend! I did not have one, so we wrestled with the drive train for way too long! Once you get the DT level with the engine, you can slide the DT forward. Getting it level is very important because you do not want to damage your pilot bushing/bearing. Sliding the DT forward you should feel the bell housing and engine block mate via the locating dowels.

Install the shifters after notching the floor board and reinstall the TC linkage.
Bleed and install the new clutch slave.

You can now install the skid and measure for the front and rear driveshafts as neither will fit because of the increased DT length. If you installed and SYE like I did, you can go cheap and use the front drive shaft from a Cherokee ($25 wrecking yard). After these are cut/lengthened/balanced, you can install them. Bolt up the tranny mount and you should be good to go.

I probably missed some stuff, but I'm just trying to get this info out there as I had many questions nobody seemed to know the answer to.
 
See less See more
#4 ·
Excellent!

I plan to do this within the next few months for sure!

Jake :tea:
 
#6 ·
Rather than your local dealership, the AX15 mounting bracket that accommodates the torque arm can be had from and on-line OEM supplier for less, these guys have it for $42.01 plus ship (typically minus state tax). Mopar Parts for Dodge, Chrysler and Jeep: MoparPartsAmerica I have used sources such as this in the past and have had my local dealership match the price. They usually himm and haw about it but usually agree to match. Good job bye the way OP:thumbsup:, this info is just to help others who are looking to do the same. I commonly see this bracket used and rusty on e-bay for more than this, so why buy used when you can get new OEM part for less.
 
#9 ·
You will need to run a 4.0 rear drive shaft, since the AX-15 + bell housing combo is 2" longer than the AX-5. The front driveshaft will work for daily driving, but I have not tested its length offroad on full droop flex. If you're worried about that you can pick up a 40" collapsed length 4.0/ax-15 front driveshaft. Our 2.5L driveshafts are 38" collapsed length.
 
#12 ·
Gonna try posting a couple of questions here if anyone's still reading this thread before making a new one.............

I'm gathering parts for my ax5 to ax15 swap

-I'm assuming I can get an AX15 from any Jeep source (YJ, TJ,Cherokee, Commanche)??
-Will the T-case from that same donor vehicle work on my yj? (so I don't have to change out the input shaft to match mine)
-since my driveshafts will be different legnths, are there donors from a salvage yard that will be a direct bolt on?

Thanks in advance. Gonna be posting a good detailed write up with lots of pics when I finish getting all the parts I need.
 
#13 ·
You can use any AX15, one from 94+ will be less of a hassle because it will already be setup for an external slave and have the 0.75" pilot bearing. If you get one from a Cherokee (And I imagine from a commanche as well) then the transfer case mounting flange will have to be reclocked, as they sit 10* lower in cherokees.

Yes, its easier to get the transfer case from the same vehicle as it will be bolt in. Be aware that the ones from a cherokee will probably have a CV style front yoke, but I just swapped the one from my 2.5L NP231 > 4.0L NP231 without issue.

A 4.0 wrangler driveshaft will work. I've been running my front 2.5L driveshaft since the conversion without issues, even offroad.
 
#14 ·
Yes, its easier to get the transfer case from the same vehicle as it will be bolt in. Be aware that the ones from a cherokee will probably have a CV style front yoke, but I just swapped the one from my 2.5L NP231 > 4.0L NP231 without issue.
do you mean that you just used your old front driveshaft from your 2.5 set-up?

Thanks for the reply, can't wait to do this swap

BTW, for anyone interested here is an good elplanation of the "reclocking" from another post.
When using a non YJ AX-15 in a YJ, the NP231 transfer case will hit the skid plate because the T-case is "clocked" 10 degrees lower on the driver side, so you'll need to address the location of the mounting holes at the rear of the AX-15.

This pic & explanation were stolen by me from fellow JF member "idaholtby", he posted this in another thread a while back.

The transfer case clocking is determined by the mounting holes on the output of the transmission. Simply redrill the holes to raise the transfer case to the YJ height. In this pic, the holes on the right on each tab are the newly drilled holes that the YJ configuration requires to clear the skid plate.
 
#16 ·
i plan on getting started ordering the parts to do this swap,but just a quick question and maybe a few more on the way as far as the 96 dodge dakota bell housing is there a certain motor size i should be looking for and when i find one is there anything i should be sure to keep on it. and just so i get it i can us any yj or tj ax15 94 and up.
 
#22 ·
I just did the same swap to my 98 jeep Wrangler 2.5, but now I have very little resistance on my clutch pedal and The Trany moves into gears witout pressing the clutch down.. I already tried Bleeding the Slave cylinder and took it out again to manually pump it.. And the trany still doesnt work. Any suggestions on what It might be? a New Slave Cylinder or master cylinder?
 
#23 ·
So it's stuck now? The clutch is not releasing fully right now? Does the release happen on the pressure plate after you take out the slave cylinder? If yes, then just replace with a complete pre-bled system if you can spend for that as long as you determined that the pressure plate is releasing properly after you removed the slave cylinder, then obviously it is in the hydraulics somewhere. If not, then it seems like a problem within the pressure plate area somewhere. Sometimes it's the opposite problem of what you are having, with this conversion, to where the slave pin is not long enough. Many people sleeve it adding one inch, or up to one and one quarter inches tops. But this seems to be not a problem in your case.
 
#24 ·
Thanks, yea, I rounded it down to adjusting the clutch peddal or something within the bellhousing.. I wanted to ask because I see pictures on here about the fork spring being on the outside of fork ball and over the ballsocket behing the fork ball itself, How is this spring supposed to be installed correctly? I replaced the Hydr Cyl with new one, re Bleed it and it has potential Resistance but the trany still enters all gears without the pressing down on the clutch. So I am stuck right there. Turns on throwout bearing sounds loose and trany wont engage into any GEAR! Grrrr!! what did you say about the clutch itself? what would be wrong, I installed it just as it is suppose to be facing proper directions and lbs.... thanks again for helping!
 
#25 ·
I'm running a stock length clutch slave pin, works fine.

I would start by removing the slave cylinder, tying it up, and attempting to drive it. If you can start the jeep, and it won't go into gear without the clutch, then the problem is the hydraulics not releasing.

If it still acts the same, your problem is mechanical and inside the bellhousing.
 
#26 ·
well the New Hyd Cyl works good now after bleeding her, but the problem remains the same is that the shifter goes into gears with or without using the clutch pedal. All Gears engage in and out. Im going to remove the Hyd Cyl and use a long screw driver on the Bearing Fork to see if engages that way or if will stop the problem. I feel that MoonshineFuel hit the jackpot with the short stock Hyd Cyl pin. Thanks Guys! Ill let you know what the problem was if I find it.
 
#27 ·
Droped the trany again.. bc I have no pressure whats so ever when moving the shift stick into all gears with or without pressing on clutch pedal. I don't understand what I am doing wrong. I followed instructions to the T , but I'm thinking the Clutch itself isn't pushing out when I tighten it up against the flywheel. That's why the bearing has nothing to push down against. hmmm?
 
#29 ·
any feedback since install? I am wanted to keep my 4 cyl TJ motor but beef up the tranny since my jeep is looking like it is going to be used off road more and for hauling a trailer (I have the AX-5)... i have a friend who is a transmission tech and would be assisting in the install...

Thanks!
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top