Just wondering if this swap is possible for the 3.8L JKs. It would seem as if the PCM has the data in it as the CRDs used this transmission and certainly other Jeeps.

I don't have a need, but this seems like something that would have a tremendous amount of usefulness to an automatic owner, increasing mechanical advantage at roll out and increasing rpms at cruise speeds.

 

I'll throw some reasons out there that I think it won't be easy.

The trans won't match the back of the 3.8
The trans is longer, so the engine would have to be moved forward some.
The pcm doesn't have the correct programming in it.
Wire harnesses would have to be changed.

Can't think of anything else. Don't know if my thoughts are accurate.

 

Thanks Ron!

I agree you would certainly need a new wiring harness and a bell housing. The rest I'm certainly not sure on.

The advantage would be getting appropriate gear sets for 37" tires and beyond, less gear hunting, better economy and avoiding the small pinion of some gear sets.

 

EDIT: most apologies... the 2008 Commander had a 3.7L not exactly the same as the JK 3.8L - see http://www.jeephorizons.com/tech/index_reference.html for other Jeep specifications.

Greetings... I am very interested in this topic, I have actually looked at other Jeep vehicles and found that the Jeep Commander 3.8L is setup with the W5A580 (Same as in the VM2.8L Diesel) close ration 5 speed tranny with a modest OD. Seems that the tranny would bolt up to the JK motors, cant imagine they are different. It was mentioned that the W5A580 is longer than the 42rle? the 42r has the dead space between the tranny and the transfer case... are both adapters the same length? Cant imagine the drive trains on the Commander and the JKU being that different... I can see that the JK may have an issue... but then how do they make the VM diesel work in the 2-doors JK if the tranny is so long? Very curious what both of you think.... Thanks again Jpopp for all your help on my tune... still messing with a few tweaks...

 

I inquired about this and a forum member whose name i cant remember told me that the newer trans was electronic shift where as the 3.8 trans was cable shift and that is year model dependant.

I had asked about a 6.4 kit with the newer trans and my jeep is lacking the pcu and harness to supt the new style electronic shifter. I was told to take the 545 trans and be happy or buy a new jeep and replace its motor and use its newer trans

 

Outside the transmission alone, I learned there were over 800 other part changes to make it happen at Chrysler. While I'm certain not all of those are necessary, it would still be a huge chore and at some point you're just better off to get a JK with the new transmission in it.

 

Hmm... 800, cosmetic? Thats disappointing. Well the swap is an interesting idea it would help the 07-10 jk's with many of the auto trans issues. We have a lot of innovative aftermarket companies, it would be interesting if someone tried the swap... I saw that the 08 commander and the 08 jku have similar V6's 3.7L and 3.8L, the commander is definitely a different drive-able big SUV with a580 trans - thanks for your thoughts

 

i would love to do this swap as i don't think the 42rle can handle my abuse once the 3.8 is supercharged. anyone have any ideas on rebuilding the 42rle as a higher spec trans, like a 46rle? anyone had dramas with the 42rle once supercharged, as i wheel hard and alot in the dunes at high speed and revs, have a big aftermarket cooler, 35's and 5.13's so thinking with the added torque from supercharger ill fry the trans in no time. thanks in advance for any ideas, info. cheers