Civi-4l80 swap T-case question

[Dock Rocker]

I am considering a 4l80 swap and because I have one sitting in the shop ready to go I am thinking about using a Civi unit.

I have the controller picked out and I have that sorted out but now I have transfer case questions.

For the people who have done this swap did you use the transfer case original to the hmmwv (I believe a 218 ). Did you upgrade to a 242 like the more modern hmmwv’s have or did you use the transfer case from a civilian truck?

Any help would be appreciated. I am tryin to gather up all the parts before the truck gets out of EUC jail.


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[Wire Fox]

So you can technically use either. I have an A1 HMMWV, so mine actually uses a 242 from the factory. The big thing you'd have to consider with this is your drive shafts: the 4L80E is longer than the 3L80, so the lengths of your existing drive shafts are going to be wrong no matter what. If you want to be able to use factory-made driveshafts, you'll have to either change the output yokes on the NP 218 to 242 style, or you'll have to just install 242. If you don't mind having custom drive shafts made, you can just have them built with the right yokes to attach to the 218.

This is a case where the "easy button" is also the best solution, as the NP 242 is undoubtedly the stronger transfer case and the U-joints on the drive shafts meant for the 4L80E-NP242 combo are a bit stronger and more readily available than the 3L80-NP218 setup. The remaining question is...what's your budget and how much work do you want to do?

 

[Dock Rocker]

So you can technically use either. I have an A1 HMMWV, so mine actually uses a 242 from the factory. The big thing you'd have to consider with this is your drive shafts: the 4L80E is longer than the 3L80, so the lengths of your existing drive shafts are going to be wrong no matter what. If you want to be able to use factory-made driveshafts, you'll have to either change the output yokes on the NP 218 to 242 style, or you'll have to just install 242. If you don't mind having custom drive shafts made, you can just have them built with the right yokes to attach to the 218.

This is a case where the "easy button" is also the best solution, as the NP 242 is undoubtedly the stronger transfer case and the U-joints on the drive shafts meant for the 4L80E-NP242 combo are a bit stronger and more readily available than the 3L80-NP218 setup. The remaining question is...what's your budget and how much work do you want to do?

Well I already own the biggest budget buster. I have a mildly built 80E on the bench now so that’s my motivation to do a civi swap.

The drive shafts are not a big concern as a good friend owns a shop that builds shafts.

I am currently looking for a 242 but no luck here locally. I also have the civi tcase that came with the transmission and also have the 218 that’s in the truck now.

I just wanted to know what everyone else has had luck with and why they chose what they chose. Since I have options I might as well have some group think.


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[86humv]

You also need a different X member, and T/C adapter.
I civi T/C might not have the proper angle when bolted up, or may not fit a T/C adapter for one a military T/C 242.
218 does not have a slip yoke like both types of 242's which is a better way to go.

 

[parklandtrans]

All,
Agree with all of the statements made above, there are a couple of other"Things" you gotta do to make the 4L80E transmission work in place of the old 3L80 trans. Lots of real good postings with pics and instructions on this website..so please do your research. P.M. Me if you have any questions, concerns, parts requests or anything you think of..!!
good luck,
Bob (Parklandtrans)