AX 15 Conversion Build Up

Well I have been thinking about starting this thread for a while, since there is not a lot of info on the AX-15 transmission swap on these forums (and a bit of mis-information - not intentional I'm sure.)

So - A bit of background: I just recently bought a 72 Bronco around the beginning of the year. I have a daily driver that I use to commute to and from work, but I tend to go on trips to the mountains a lot (get around 25 days of skiing in a year) My car, an 05 Mustang is possibly the worst vehicle outside of a prius to drive in the snow. I have literally gotten snowed in this last year, and had my E-brake freeze and strand me. (E-brake was my fault for using it but still) so I started thinking about getting a new vehicle. The problem I had with that was 2 fold: 1) Value: selling the mustang and getting a new car payment is not economically logical. 2) I don't really like any new SUV-type vehicle offered. Too much plastic.

So. I started thinking about the Bronco, although I know it's still not a great choice for long distance trips, and its not ever going to be economical, it is something I can work on in my spare time, will hold up to pretty much any conditions I can think of, and lets me have a cool classic vehicle.

From the PO, the 72 came with:
Stock 302 w/ electronic ignition.
Chevy Disc brake conversion
3-inch suspension lift
32" Tires
D44 front/9" rear
New gas tanks
Roll Cage
A bit more rust than expected
3spd /w hurst shifter, stock D20 T-case

One of the things I knew I would want is a newer 5-spd trans so that freeway driving/trips would be doable. I am NOT looking to trail ride this rig hard. I will do some off-road, I am sure, but no really hard stuff. This led me to consider the NV3550 that a lot of people have put in. Unfortunately, I could not find one for the life of me. Patience is also not my strong suit. I found an AX-15 out of a '96 Jeep Wrangler 4.0 that had been completely rebuilt in October of 09 (got the shop receipt and warranty with pickup). Got the Adapter kits from AA (significantly more expensive than the trans itself) and ripped into the bronco.
(More to come)

Hopefully you have the axle gearing to support the OD feature. Otherwise you've gained nothing but extra gears. Good luck with your swap I dont think its going to be much of a issue as its no different than the 3550 swap. So you will have some people that can help answer any questions if needed.

Id like to know how this goes, there's a zillon of those AX15 trannys out there and at reasonable prices.

(And now onto the actual work, and questions that I have)

A bit of info that I forgot to post about is that I got the rig running again yesterday! Talk about a sense of accomplishment, I still cannot believe that something isn't broken - went together right the first time.

So the original - and Tear-down: I ripped all the interior out to get some rust taken care of - wont be getting it all back in until the trans is done. One of the things that immediately hurt me was the exhaust. there Dual Flowmaster 40's make a lot of noise (a bit more than I like TBH) but the H pipe makes total removal of the exhaust impossible without droping the gas tank - I did not want to do that. So I left it in. Made life difficult to work around the pipes.

(Be nice about my low budget floor pan repair - it's going to get carpet, so nothing will show)

broncnaz said:

Hopefully you have the axle gearing to support the OD feature. Otherwise you've gained nothing but extra gears. Good luck with your swap I dont think its going to be much of a issue as its no different than the 3550 swap. So you will have some people that can help answer any questions if needed.

Click to expand...

I have 4.11's in the axles. It, seems, though it's only been driven about 30 miles since I got everything in, to be a MASSIVE improvement. 1st is a bit low for my tastes, but 5th really really helps at highway speeds.

Ok:

So, I got everything out (Btw, the tech article about removing the 3spd is very good, can't find it right now ?:? but I used it to help with removal)

I happen to have a mustang T-5, that I was originally going to try to put in the Bronco, got talked out of that one ;D Decided to take a picture of all 3 for comparisons sake. Also a few pics if the input shafts for the AX15 and Toploader. From Left to Right the order is: 3-spd Toploader, AX-15, T-5. The T5 is a LOT lighter than the AX15 or Toploader. Considering that the T5 is an Al case, but has 5 speeds, and is lighter than the 3-spd, It would concern me. The AX15 is about equal back-hurts-a-lot factor to the 3spd.

As you can see form the Input shafts the AX15 has a bit longer of a bearing surface. the AA instructions say in big red block letters that you must cut .250 off the AX15 shaft. Not sure about that, but I did.

Are the adapters the same as for the 3550?

I will definitely be following this thread! Good post so far, keep on posting! Just a few questions. What adapters did you get from AA? I see they have the SBF to AX15 adapter but not a AX15 to D20 adapter? Is that because it is the same as the NV3550 to D20 adapter?

Yeah you should be fine with 4.11 gearing and 32 in tires.

nik said:

I will definitely be following this thread! Good post so far, keep on posting! Just a few questions. What adapters did you get from AA? I see they have the SBF to AX15 adapter but not a AX15 to D20 adapter? Is that because it is the same as the NV3550 to D20 adapter?

Click to expand...

Well, this is a good time to talk about that...

I got 2 kits from AA (Well 1 from BG, but it was the AA kit. Not paying sales tax in CA is a bonus)
One is the AX15 to SBF. This kit is NOT interchangeable with the NV3550. The biggest differences between the AX15 and the NV3550 are probably bell housing side. The AX15 kit makes use of a single part that is both the front seal for the input shaft and counter shaft, and a spacer for the bell housing. From what I can tell the NV3550 just has a new pilot bearing retainer. One thing the AA kit Does not have is a new clutch plate. This was a little disappointing, but I ended up being able to find one locally. Attached are the pics of the Adapter installed. Notice the original bearing retainer discarded to the right of the second pic.

For reference: The AX15 and AX5 look similar. But they are not, the AX5 is not built for the loads the Bronco will see, the part number of the AX15 I have (and I think its common for all 94-96) is: 52108047

Also, with the AX15 - you want to get a 94+ model or is it 96+? somewhere in those years they switched from an internal slave cylinder to an external slave. The internal slaves were prone to leaking and causing premature clutch failure. I chose to continue to use the mechanical linkage, but you could do some mods to use the hydraulic one.

And the T-Case:

Tcase adapter is the Jeep 23 spline to Bronco D20 Kit. The same kit is listed as a Nv3550 to D20 on the AA site. I think they renamed the kit because it services both transmissions.

This kit is well covered on this site, so I wont go into great detail - but will point out a few things that I found.

1) As others have said. When you remove the Input gear from the Tcase, make sure the Tcase is face up - or you will spill the needle bearings all over the place. I did. Then spent 1/2 hour finding them all.

2) Slightly disappointed with the AA kit here. First, the overall machining quality is fairly poor. The parts are cast Al and then speed lathed to fit. Mine did not slip fit the bearing on the input shaft correctly. (The Input shaft is very very nice BTW, NOT something I would be able to do by myself, even with access to a machine shop.) I ended up taking some fine grit sandpaper to the bearing surface to get all the burrs rounded off so that I could get the bearing seated. It still was a bit of a pain. went in eventually.

The input gear for the D20 has a C clip on it that is a PITA to remove. Lucky me, I have the correct tools for the job, but I figured that there would be a brand new C clip for the AA kit. Glad I decided to keep the old one just in case. the kit costs $450, and they can't include a .30 C clip? %) (No, it was not just a missed part, there was no clip on the Bill of Material for the Kit.)

Engineering wise, I still can't figure out why the kit is made in 2 parts - Part 1 is the Bearing retainer, Part 2 is the Adapter, they fit together, and pretty much from 1 piece when assembled. All it does is make 1 more place for the Tcase to leak from. Not a big deal, but kinda wierd.

One more thing, The Adapter plate LOOKS like it is symmetrical. It is not. You need to line it up the the transmission properly or the bolt holes will not line up

Edit: On second thought, the reason for the 2 parts is probably so that there is a slight amount of play in the shaft, and will keep the bearing from being side loaded, which would lead to premature failure.

so the rear adapter is just for the drive? The tc bolts to the transmission itself?

RustyShackelfor said:

so the rear adapter is just for the drive? The tc bolts tot he transmission itself?

Click to expand...

No, there is an adapter (see the large disk in the last pic of the last post, that's it) it goes in between the Trans and Tcase

didnt even see it and was looking for something like that

Cool. Thanks for answering my questions. I prefer the mechanical linkage anyways so it wouldn't matter what year transmission I got just as long as it's not the AX5 or BA10? Everything driveline-wise I assume should be the same, did you use the stock shafts? Another thing I would have to deal with is how to mount my twinsticks, did you have to modify your T-case shifter at all? How long did this swap take you?

I see this as a fairly simple and cheap conversion (I'm a broke college kid) and I, unlike others, have a little faith in the AX15. I've seen my brother abuse his...towing a trailer w/ 3 motorcycles and the back of his car full of crap over I8 in 5th...if that isn't as abusive as you can get I don't know what is.

Nik

does the internal slave cylinder really matter since you use a Ford bellhousing or is it somewhere else inside the trans?

Nik:

As far as shafts go, if you mean Driveshafts, yes they are the original - no mods needed. The Tcase shifter mechaniaim was a bit tricky, I will go into that in further detail prtobably tonight. the kit only works with the T-shift style, not J. I think twin sticks work on 1 pivot point right? You may need a new shifter mount bracket for the twin sticks.

As far as time, IF you have everything up front - should only take a week or so, depending on what goes wrong/how much time you have. It took me about a month, but a lot of that was waiting on parts and re-doing things that I did wrong to begin with.

Rusty:

I am not sure about the internal slave as my trans had the external, and was simply removed. I would thing that so long as the adaptor fits, it wouldnt be a problem. I dont know if the adaptor plate would interfere with the internal slave though.

Yea I meant driveshafts sorry. I have the T-shift but twin sticks. You are right they have a single mounting point using a bolt that goes through the 3 speed intermediate housing. I think I will be able to fabricate a mounting system similar to the NV3550 swap with twin sticks.

Still would like to see what you did though.

I saw a trans that looked like this today. How do you ID them?

RustyShackelfor said:

I saw a trans that looked like this today. How do you ID them?

Click to expand...

I would suggest this link for some basic research:

http://www.novak-adapt.com/knowledge/ax15.htm

Here you will find info on year/model they were used on. Generally, any Jeep 4.0L post 88'. The 4cly engines had the AX5 or BA-something something - which was/is a bad choice, even for the 4cly engines. (I know too much about Jeeps right now :-X)

Other than that there is an ID number at the top of the Trans (mine is in one of the posts above) if you do a Google search on that number a list of relevant transmissions and years offered will come up.