Np231 For Ax-15

[onlyinajeep726]

What Jeeps can I pull a 231 transfer case from for a successful mate to an AX-15 transmission?  (Note: the AX-15 in possession is from a '96 XJ)

 

In my research, I have found out that the AX-15 has a 23 spline output shaft and the 231 needed has to have a short nosed 23 spline input.  Is this correct?  Gurus, please bestow some information upon this noob. :bowdown:

[onlyinajeep726]

Also, while we're on the subject, I need to know what other parts I need for my AX-15.  I have the transmission itself, the bellhousing, a used external slave (which I'll likely just buy a new one), a used shift fork and used throwout bearing attached.  Correct me if I'm wrong, in addition to these parts, I need a flywheel, friction plate, clutch and pilot bushing (should come together in a kit if bought new, right?) and what else?  I'm really new to the manual transmission world.  I will be swapping out a 2.5L/AX-4 combo for a 4.0L/AX-15 combo in the MJ so I have to piece it all together.  Just want to make sure I have everything I need to make this the most successful swap possible.

[Geonovast]

This for your 88?

[onlyinajeep726]

No, my '86 MJ.  And yes, I've been warned of the difficulties ahead when trying to stuff the 4.0 into a pre-'87 XJ/MJ lol.  That can be overcome.  I just don't know jack about transmissions.

[Geonovast]

Wasn't actually what I was asking for.  What year is the 4.0 you're putting in?

[onlyinajeep726]

Sorry, almost everyone I've told my plans to for the old girl have told me "you're doing the impossible."  I shouldn't have made an assumption and I am sorry.

 

To answer your question though, the engine is a remanned Renix that will come from a '90 XJ that is currently mated to an automatic.  I will also be pulling the computer, wiring harness and dash from said donor.  I will have to trick the computer into thinking that the AW4 is still there by jumping some pins in that harness.  Other than that, I should be okay, right?

[mvusse]

The TCU is completely separate from the ECM, so I'm thinking the computer really shouldn't mind you having a manual transmission instead of an automatic. I believe, but have no proof to back this up, that the only difference between the two ECMs is the manual having the provision to control a shift light if the transmission is equipped with a switch for it. That switch will tell the computer when the transmission is in the highest gear or reverse, or if it is in any other gear so it doesn't illuminate the shift light when there is no higher gear to shift to.

 

You will still have to find a Renix 4.0 mated to an AX15 to get the flywheel from. I seem to remember a thread a few months back showing that for most (all?) aftermarket 4.0 flywheels the trigger location for the crank position sensor is in the wrong location. Also, do not have a 4.0 flywheel resurfaced, as the surface is not supposed to be flat, but has a slight cone shape to it. Resurfacing it on a lathe will remove that cone shape, instead making it perfectly flat.

[Geonovast]

I think the auto computer needs to have the pins for the NSS jumped, or it won't allow it to start.

 

No need to apologize, and what you're doing certainly isn't impossible.  I just needed more information on what you were doing to which truck.  What year the 4.0 is matters as far as which pilot bearing to get.  Since you're mating a 92+ AX-15 to a 87-91 4.0, you'll need a pilot bushing for a 74 CJ with a 304.

 

Also remember the AX-15 uses a different crossmember than... everything else.

 

I think, (not 100%), but you should be able to use a long shaft 23 spline input for the T-case.  I don't think it'll hit anything, but you may be able to just have it machined down a bit if it does.

[mvusse]

I think the auto computer needs to have the pins for the NSS jumped, or it won't allow it to start.

 

No need to apologize, and what you're doing certainly isn't impossible.  I just needed more information on what you were doing to which truck.  What year the 4.0 is matters as far as which pilot bearing to get.  Since you're mating a 92+ AX-15 to a 87-91 4.0, you'll need a pilot bushing for a 74 CJ with a 304.

 

Also remember the AX-15 uses a different crossmember than... everything else.

 

I think, (not 100%), but you should be able to use a long shaft 23 spline input for the T-case.  I don't think it'll hit anything, but you may be able to just have it machined down a bit if it does.

 

One of those obvious details I forgot about.

 

The cross member can come from any 87 through 96 Comanche or Cherokee with an AX15. Probably 97 through 01 as well, but not sure on those.

[onlyinajeep726]

I failed to mention that I have the crossmember in possession from the same '96 XJ, as well as the rubber transmission mount and some other various pieces the seller supplied.  I did not know that he flywheel had to be from a Renix, but that makes sense now for the reason given.  Also, why does the pilot bushing have to be from a '74 CJ with the 304?  I thought that could come from a Renix XJ/MJ that had the AX-15 from factory?  Or does this have to do with the fact that the AX-15 I will be using is an external slave?

 

Also, jumping the NSS plug is what I think I was thinking about to "trick" the computer.  I was reading threads a while back talking about swapping out an AW-4 in favor of the AX-15 and that was mentioned.  There's so much information out there on the interwebz.  Anyway, keep the information rolling in.  I'm going to make a list of components that I'll need to order for this.  I think as far as the engine goes, once I make the modifications to the firewall, hood and radiator support, the wiring should be easy enough to get back together.  Afterall, I'll have the donor right next to my MJ.

 

 

Edit: Geonovast, I just saw your post on another thread of mine that I made when I bought this AX-15.  If I had seen it before, I wouldn't have asked some of the same questions twice haha.  But either way, thank you and mvusse for the great information thus far. 

[Geonovast]

Flywheel doesn't have to be from a Renix 4.0 with an AX-15.  Just a Renix 4.0.  The BA 10/5 and AX-15 used the same flywheel, as long as the flywheel is for a Renix (87-90), you'll be good.

 

The pilot bushing has nothing to do with external slave, but year.  When they switched to the AX-15 mid 89, they kept the same size pilot bushing as the BA 10/5.  In 92, the tip of the input shaft was made bigger, as well as the hole in the crank made smaller, therefore entirely new bushing.  To get a 92+ trans behind an 87-91 4.0, you need the CJ bushing.

 

[onlyinajeep726]

Am I correct to assume that the flywheel from my 2.5/AX-4 is non compatible with the 4.0/AX-15?  That would be too easy and convenient, wouldn't it?

[Geonovast]

You are correct, they're not even close to the same.

[onlyinajeep726]

Thought so...

 

Ok, so far on the list of parts I need to obtain:

 

- external slave for '94+ AX-15
- friction plate and clutch
- pilot bushing from '74 Jeep CJ with the 304 engine
- Renix flywheel from '87 - '90 4.0L MJ/XJ
- 23 spline NP231 transfer case

 

Parts I already have:

 

- '96 AX-15

- external slave 4.0L bellhousing

- used shift fork and used throwout bearing

- appropriate crossmember

- rubber transmission mount

 

Anything else needed that I'm missing?

[Geonovast]

Hold up just a bit.

 

Do not get a 91 flywheel.  Renix is 87-90.  91 was the first year for the HO.

 

They just took another year to change the pilot bushing.

 

91 was kind of a stupid year.

[onlyinajeep726]

Ok, but other than that, does that look like a complete list of stuff I'll need?  I want to get the most complete list so I can post it for others to go by if they're doing a similar swap.

[Geonovast]

You still need linkages, 4wd handle, linkage brackets, and driveshafts.

[onlyinajeep726]

Gotcha.

 

As far as that pilot bushing is concerned, I guess this is the correct part: Pilot Bushing

[mvusse]

Flywheel doesn't have to be from a Renix 4.0 with an AX-15.  Just a Renix 4.0.  The BA 10/5 and AX-15 used the same flywheel, as long as the flywheel is for a Renix (87-90), you'll be good.

 

My bad. I forgot about the piece of poo Peugeot. To be completely correct, I meant a 87-90 4.0 with a manual transmission.

[mjeff87]

^{Small but essential, you will also need the flywheel bolts, either new or from the donor.  Flexplate bolts (from the auto trans) will be too short to use with the flywheel.}

^{And you jumper the "B" and "C" pins on the NSS harness to get it to fire.  I've got a pic of it somewhere, I'll post if I can find it.}

 

^Jeff

[onlyinajeep726]

Thanks a ton guys for the info!

[jimoshel]

 Quote// Also, do not have a 4.0 flywheel resurfaced, as the surface is not supposed to be flat, but has a slight cone shape to it. Resurfacing it on a lathe will remove that cone shape, instead making it perfectly flat.//quote

 Not meaning to hijack thread but I am curious. Why can't you machine the surface flat and use it? As far as i know, except for some early Fords, all fly wheels are flat and seem to work OK. Do they use a special disc and pressure plate? Can't a disc from another year be used? How deep is the cone? .001 inch? 3/8"? 1/2" ? Curious minds want to know. :dunno:

[onlyinajeep726]

I've been wondering about that too since it was mentioned.

[jimoshel]

Just checked Auto Zone part numbers for a '88 4.0, '91 4.0 and a 96 4.0. They list the exact same part number for just clutch disk and the clutch set. Disk and pressure plate. Same specs, clutch OD=10.4. ID=1 1/8. spline count=10.

For all 3 years. So now can somebody explain why retaining the cone is so important?

[shawn]

 any more info on this?  and if '91 is an oddball year ( as far as pilot bushing size is concerned), does that meant that i should be picking up a 304 pilot bushing when putting a '95 external slave ax-15 into my '91 that has an internal?  ( both 4.0 ).