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Discussion Starter #1
Hi just new to this forum.
I recently bought a 1989 jeep wrangler from a buddy of mine who runs a Diesel shop. The previous owner of the shop did this swap. I'm pretty fresh to the diesel world. Im wanting to to know what transmission is in this jeep. My buddy is unable to give me any info. The jeep was sold by previous shop owner to someone who blew something in the engine. So he brought it back to the shop where it was built but now owned by my buddy. So it was going to cost him $6000 for the repair plus $2000 for the diagnostic on it. The end of the day the owner cut his losses and left it at the shop. Now I own it with very little information about it. All I know is that its has a 4BT in it with a 6 speed manual transmission. How many possibilities could this transmission be? Or how can I tell what it is? Thanks in advance for any help.
 

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BAC,

Take a picture of the transmission.. some possibilities (though some may be improbable)
NV56, ZF6, Eaton Fuller FSO, Tremic, TTC Spicer ES (maybe ESO) I would lean to it being a NV or a ZF.

Cj
 

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Could also be a G56 Mercedes unit which is what's on the latest Dodge Cummins. You said it's in a Jeep Wrangler. All the 6 speeds tend to be quite large and long. Usually makes a drive train too long for a Jeep. More typical transmissions are the ZF5 or NV4500 which are 5 speeds. I see you are in Canada. An $8000 repair bill is getting close to a whole swap. Are you sure this is a 4bt. You can find rebuilt engines for $6000. $2000 diagnostics sounds a bit extreme on a purely mechanical 4bt. Wonder what he broke that cost $6000.
 

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Discussion Starter #4
My bad. I had jist finished reading about some 6 speeds and i guess it got stuck in my head.. it actually is a 5 speed not 6. Pictures to come soon
 

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Discussion Starter #5
Could also be a G56 Mercedes unit which is what's on the latest Dodge Cummins. You said it's in a Jeep Wrangler. All the 6 speeds tend to be quite large and long. Usually makes a drive train too long for a Jeep. More typical transmissions are the ZF5 or NV4500 which are 5 speeds. I see you are in Canada. An $8000 repair bill is getting close to a whole swap. Are you sure this is a 4bt. You can find rebuilt engines for $6000. $2000 diagnostics sounds a bit extreme on a purely mechanical 4bt. Wonder what he broke that cost $6000.
It is a 5 speed made a mistake while typing I'll send some pics
 

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You've looked for a tag on the transmission?

While you are under there, might as well look for the tag on the transfer case.

That looks like a nice, clean, motor install.

Roy
 

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I think that might be a AX15
 

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Damarble, I believe you may be correct on the AX15. One thing I see that doesn't look too good is the turbo on the engine. That appears to be a large H1C off a Dodge 6bt. That thing would be terribly slow to spool on a 4bt. The small H1C found on the 4bt wasn't all that great, but that appears to be the big one. A Super HX30W would be light years better and would have the same 4" intake so no plumbing change there. Might have to rework the IC and exhaust plumbing some for that one.
 

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Discussion Starter #13

  1. Damarble, I believe you may be correct on the AX15. One thing I see that doesn't look too good is the turbo on the engine. That appears to be a large H1C off a Dodge 6bt. That thing would be terribly slow to spool on a 4bt. The small H1C found on the 4bt wasn't all that great, but that appears to be the big one. A Super HX30W would be light years better and would have the same 4" intake so no plumbing change there. Might have to rework the IC and exhaust plumbing some for that one.
    127316
 

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Can't really read that tag but I assume that's the transfer case. Stock case on Jeeps would have been a NP231
 

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Can't really read that tag but I assume that's the transfer case. Stock case on Jeeps would have been a NP231
NP-231-J so Jeep.
 

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Looks like an ax15 /np231 like mentioned above. I wonder what bellhousing they are using.
The adapter looks like the Ford/Cummins, between that and the thickness of the trans to bell adapter would also point to a Ford bell as the ford Input shafts are just less that 1" longer than Mopar's are and I'm thinking that it's the same for jeeps...$.02
 

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Yes, that transmission can be adapted using a SB Ford bellhousing which has butterfly bolt patterns for transmissions. Novak has a kit for that. They also have one for AX15 to GM bellhousing. There are even kits out there for SAE3.
 

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That’s cool, never knew that. I have heard of guys running the ax15 behind a 4bt but wasn’t sure how. I like the ax15 personally.
 

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As long as you don't abuse it you may be OK. I emphasize the word may. From all I've been able to find, the AX15 has a torque input rating of around 300 lb ft. That isn't much when you're talking a 4bt Cummins. That would be roughly 120 HP on the 4bt. A bone stock 105 HP has 265 lb ft. Start tinkering with the power level of the 4bt and you'll probably have transmission failure. Go up to 200 HP and you'll be around 450 lb ft which is 50% over the transmission capacity. Just keep the brain in contact with the right foot and don't try doing burn outs or you may have to pick up the pieces.
 
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