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Np231 For Ax-15


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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?

I've always wondered why nobody ever answered my question.

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From previous experience you are gunna have some issues mounting the cross member to support the tranny and transfer case. True almost every hole its there already (should have to drill 2). I would go out and buy a $#!& ton of RIV Nuts so you can secure it. Also you should have to fab up a custom way to attach the cross member to the tranny

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Everybody has pretty much listed the important to know things.  If you feel up to it you can convert a 21 spline input NP231 from a BA-10 to a 23 spline input.  The parts will cost about as much as buying a used TC (or more) but it is an option.  Don't forget to check early (1993) ZJ's for AX-15 parts you need as well.  My TC, Bellhousing, clutch fork, and linkages all came from a 93 ZJ i found at the local U-pull for $90.

As BootsNTrucks said, 6 of the 8 bolt locations will already be present on the frame, but you will have to create the last two holes as they don't exist (they didn't on my 1988).  Tap the already existing holes with an M10 x 1.5 which is what the factory threading was for the stock holes.  The last two holes you can drill out and as he mentioned use Rivnuts.  http://www.grainger.com/product/Rivet-Nut-5NNN2 I have two of those exact ones in place right now, but once it warms up I am going to go back and tack weld them in place on 3 or 4 spots to ensure they stay.

As far as mounting the trans to the crossmember, there is a specific bracket to the XJ/MJ AX-15 that you will need.  From what I ready you said you had it, and if that is the case you will simply need a new mount.  If not, you can still purchase this bracket new, and I can link you to the company I ordered mine through for $78 shipped to my door. (Post 4 in this thread has the link and part number) http://comancheclub.com/topic/41501-transmission-help-please/

As far as the clutch, I ordered a SACHS clutch for the year of my truck even though my transmission is an external.  The splines and shafts of the input shaft themselves are the same, so it will work just fine.

Regarding the flywheels.  When installing mine I noticed that the bolt pattern to the crankshaft is actually slightly offset on a couple bolts and will only line up one way. With the tone ring for the CPS being part of the flywheel it needs to be installed a certain way in order for the computer to have the right position for the crankshaft.  So, unless you plan on going with a different solution for the CPS signal, this is why just any ol' flywheel will not work.

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 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 ).

  sorry for the tread hi-jack, it's just that i could really use the answer to this as my truck is going into a shop tomorrow and theyre reluctant to even do the job as they are not jeep experts and i told them all should be fine based on my research.  - now this new ( to me) info pops up ...

  here's a great and simple thread on what I'm doing, but it doesnt mention the pilot bushing issue .

http://www.jeepforum.com/forum/f12/leans-ax-15-external-slave-swap-pics-965067/

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I resurfaced my XJ and MJ Renix flywheels many years ago with a clutch change and had no problems. Never heard of a coned flyeheel. I bought new flywheels for the second clutch change because I didn't want to resurface twice. Also I think the AX-15 can use any lenght input shaft from a 23 spline 231 tc.

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I've done 2 AX15 conversions. One came with the tc so no problem. I was going to rebuild my 231 with a 23 spline input shaft but found a rebuilt one for cheaper than I could do it. Anyway IIRC the guy at Davys Jeeep told me That any lenght input shaft would work. You might check with him.

 

http://www.daveysjeeps.com/specials.html

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The AX-15 came from an XJ, right?   The AX-15's in Wranglers have a different adapter that clocks the t-case drop down more than the XJ/MJ.

 

On that subject, has anyone swapped one of these adapters?  I have what is supposed to be a low-mile AX-15 from a Wrangler and it would be nice to put it in my MJ. 

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The AX-15 came from an XJ, right? The AX-15's in Wranglers have a different adapter that clocks the t-case drop down more than the XJ/MJ.

 

On that subject, has anyone swapped one of these adapters? I have what is supposed to be a low-mile AX-15 from a Wrangler and it would be nice to put it in my MJ.

My AX-15 and 231 came from a Wrangler. The transfer case is clocked upward and hit the floor boards. It's a simple as pulling them apart clocking it down, marking the bolts and redrilling the tranny the angle you want it to sit. Took me 45 mins. Mounting it with the cross member was a bigger pain than the clocking step.
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I've got a MJ AX-15 sitting next to the Wrangler AX-15 and the adapters' holes for the t-case are certainly different.  I assumed the YJ was down, but I suppose it could be clocked up more, but it sure seemed like that would be too much.

The MJ one came out of my truck.  It was replaced it with one from an XJ that was supposed to be in good shape, but turns out to be in worse shape than my old one.  The Wrangler one came from CL and the PO said it was for a TJ, but I'm skeptical since its an internal slave version.  It is VERY clean though... like no valve cover has ever leaked on the bellhousing and very little road grime.  Considering the all the wet weather we have here, it's either low mile, was never driving in the rain or they were anal retentive detailing a tranny they were selling on CL for a low price.

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Just so it's know, an NP231 from an early ZJ also works (as I mentioned before).  That is exactly what i have in my car.  Don't pass up the ZJ's in the junkyard without checking, because they seem to be more common than XJ's (At least around here).

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