4x4 - Home

Misc AW-4 Information


The following comments were extracted from a thread on JeepForum.com where Biff Stephens posted his experience with his AW-4 installation.  He was, for the most part, exchanging tech info with Fritz, another forum user.  I obtained  Biff's permission to include them here as they will be easier to locate for all who are looking for AW-4 swap info for their TJ. 


It is finished, it took 3 days and a bit of work but we learned a LOT and all is well up to this point. I have some pics but not here so the post will be dry for a while. I will post my thoughts and road blocks we ran in to while doing it.

First of all, there are 2 great write ups I used for this. They are below.  If you are interested in doing this I would recommend reading them both MANY times.



Removal.....went without a hitch doesn't it always? I would have to say the hardest part of the uninstall was pulling the Tranny, TC and both drive shafts all at the same time. We had some hands so it was not all that bad.

Next was the taking the TC apart to get the input gear out to get it shortened. This was not all that easy. You pretty much have to take apart the whole TC and remove the shaft. I guess I had missed the complexity of this in the write up. For someone that has does a TC rebuild I am sure you will have no problems.

Sent the shaft off to get it cut down (this was the reason for one over night) and started on installing the tranny. This went pretty well with no issues.

We decided to do the wiring in the morning of the second day. This was actually REALLY easy...it was one of the things I was really worried about. The key I feel is I have the complete wiring harness for the XJ the tranny came out of.....We removed it from the harness without cutting many wires and all the colors matched and were already connected. We did have to lengthen the harness but this was not an issue at all.  After this, there are 9 (I think) wires to tie in to the TJ harness.

Got the input shaft back at noon the next day. This is where we started to have issues.  We put it back in and went to put the case up and it would not go in.  Hmmmm......so long story short we ground on the input gear for a bit until we were close and the TC went in with a little help.

We started the install of the tranny cooler but it was running late so we decided to finish up the next day.

The next day was making sure all the T's were crossed and I's dotted. Tranny cooler, drive shafts, tranny and TC fluids, shifter and whatever else I forgot.

So the time has come.....starting it.....turn the key.....no start.....I did not have a clutch in SO the clutch safety switch was not activated. So I did the mod where you add the 20 amp fuse and it turns that off.

Waa Laa.....

Everything started and ran fine. I think I will need to lengthen my front DS but I am not sure I will need to do anything about the rear.  I might need to re-point my pinion angle.

All is good and I am very happy with everything.  I cant wait to go wheeling again to try it out.

I am tired so if I forgot anything give me a break.  I will try to add it.

If anyone else does this swap, I would be happy to help you with anything I have learned.  Anything short of grinding that input gear.

Good luck,


I had one concern when I read what you posted about mounting your np231. How much clearance did the input shaft have before it bottomed out?  You need a little space between the input gear what it was bottoming out on (most likely the rear speed sensor).  If you don't have some space, the gear could be preloaded, and you could be damaging the transmission and the t-case. Just something to be aware of.

Have fun with your new tranny!


I just took it on its first 50 mile drive. Everything is going really well so far. I am interested in the D300. I really like the twin stick option.  I can't afford an Atlas really and as you said the D300 has an upgrade path.

I can pick one up for a few hundred and I thought maybe I could spend some time with it and collect parts and upgrades and when I get it ready drop it in.

About the input shaft.  I will go into more depth.  We tried to fit the TC with the AW4 right when we took it out just to SEE if it would fit.  It did not, of course, so we sent the input gear off to get it machined.

Here is my screw up.

"Here are the measurements from the snap ring after the input shaft was removed. Short shaft is 1.350 where the long shaft is 2.100. These numbers were confirmed by Advanced Adapters."

That is a quote from Bob's AW4 swap...if you take 1.35 from 2.1 you get .75.  So I sent the shaft off to get 3/4" taken off.  It cost more than I had planned but it was done and I was ok with that.  We get it all back together and go again AND it is still hitting.  It just was not making sense.  It was very perplexing......so I found this...


Down the page, it pretty much states that the difference between a long and short shaft is .9".

So now I thought I had not ground enough.....so we started grinding. This went well.....we did not heat it up a lot, went slow, and used lots of cooling water.  It still would not mate up.

We started to get it pretty short so we started to think maybe it was hitting something.  We "think" that it was hitting the rear seal of the AW4.  Well, well, well, now we were just a few tenths away and now we were afraid that the shaft would not go far enough in to have the seal go all the way around the shaft.

So we put a few bolts on the TC and started to pull it together.....all went well and it did go together with not too much effort.

I guess I screwed up but I am not sure......it seems to have worked.  We also decided not to re clock the TC as well. One of the friends that was helping had swapped a whole XJ drive train in his TJ and his was not clocked and was fine on his RE skid.  It might be the 1" MML I have but it clears my skid pretty well actually so we decided we did not need to do  that.

I think I will stick with my small brake pedal.  At the least I might weld the clutch to the brake pedal.  I am not sure right now.....we shall see.

So it is still in progress.....a lot of we shall see's.

Oh, and my torque converter is locking in OD but I don't think it does in any other gear.

I hope all of this info helps somebody.....LOL


Ok, well that sounds like the input gear is probably all right then. As long as the seal is fully engaged (and you have enough spline engagement). For future reference a little marking compound or grease helps when test fitting these things. Makes it easier to see were things are lining up, what is hitting what, etc.

To test your convertor in 3rd gear. Get up to speed (in 3rd of course).  While holding your speed, tap lightly on the brake pedal. You should notice a slight (couple hundred RPM) change in the rpm. When you release the brake pedal the rpm will drop back down. I think the convertor will lock in 2nd too, but I am not sure and it would be hard to test using the
above method. I would be mostly concerned about 4th and 3rd lockups.

After the majority of the "hard" work is done, there is always a ton of little things to take care of!  BTW, the junk yards are full of jeeps with automatic pedals.



I just wanted to report that everything is working well.  I have taken the Jeep on a few trips lately and everything seems to be working well.  At this point, I need to start cinching up some loose ends I have.  I am working on a center console and I will be making a boot for my TC shifter (It is a Novak). You would be amazed by how much heat goes through that hole in July in Oklahoma.

Another loose end, so to speak, is the reverse lights.  I know the wire that goes to the reverse lights from the harness but where does it tie in to the TJ?  I read over (scanned) the write up again but did not find it.

Any ideas would help.



Hey Biff, glad everything is working great so far. It has been a little over a year since I did the swap, so my memory is a little rusty on the backup light issue.  But I'll try to get you pointed in the right direction.  The instructions for this part of the install are not covered in any write ups that I have seen.  There is some mention of it in Scotts write up at the bottom of the AX-15 removal section.

The backup sense for the TCU is on pin 18, and is a BR/LG wire. It receives it's signal from the Transmission Range Sensor. This tells the TCU that the transmission is in reverse. This is the wire that needs to be tied into the TJ harness.

On the TJ, the backup switch for the AX-15, there was a jumper that was removed that went to the backup switch. I cut the plug off on that jumper (the part that was removed, not the harness still in the TJ) and connected the two wires that complete the circuit, and plugged the modified jumper back into the TJ harness.  As if the former AX-15 was in reverse, bypassing the old switch.  I believe the wires were VT/BK and VT/WT.

Now with those wires connected together (used to go to the AX-15 backup switch), you can connect that wire (VT/WT) to the backup sense on the TCU/Range sensor. I believe you need to cut the VT/WT wire and connect it to the backup sense.  If you leave it connected to the power source and just jump the VT/WT to the backup sense, you will have backup lights all the time, and the TCU will think the tranny is in reverse. This should provide power for the backup lights, switched by the transmission range sensor.

This is basically how the Cherokee is wired up. I was fortunate enough to have the FSM electrical sections from a '00 XJ, and '97 TJ, so I was able to figure it out from the wiring diagrams and pin-outs.





4x4 Off-Road    Homestead    Firearms    RC Models