NP247 swap

[atmafox]

Hey everyone,

Anyone done a swap for an NP247?  I've decided that's the t-case I want for its driving characteristics and generally rear-biased nature.  Doing some reading it should be a pretty quick fit up but I haven't been able to find many details beyond that so going on a fishing expedition here.  My 119 viscous couple is well and truly dead and I see little point in sourcing and installing another of roughly the same age.

Thanks!
-Andrea

[atmafox]

Well, I've got my NP247 and it looks like a relatively painless swap -- except for the prop shaft.  The 247 uses a slip yoke and as far as I can tell no one makes an SYE for it.  The 119, from the Eaglepedia, uses a u-joint flange.

I'll see if I can get a good look at mine tonight but I think that's right, so... yeah.  Custom prop shaft time.  Which sucks, since I'll probably need another custom prop shaft when I get the Ford 8.8" rear end under her.  Wish I could wait on the t-case swap but this 119 has gone rapidly downhill.

[Taylor]

Not sure if you have looked into these before.
https://www.midwesttrans.com/np247-jeep-transfer-case/
Other than that I don’t know much about them.
Let us know how it goes and good luck.

[TheBirdman]

Well, I've got my NP247 and it looks like a relatively painless swap -- except for the prop shaft.  The 247 uses a slip yoke and as far as I can tell no one makes an SYE for it.  The 119, from the Eaglepedia, uses a u-joint flange.

I'll see if I can get a good look at mine tonight but I think that's right, so... yeah.  Custom prop shaft time.  Which sucks, since I'll probably need another custom prop shaft when I get the Ford 8.8" rear end under her.  Wish I could wait on the t-case swap but this 119 has gone rapidly downhill.

Actually, if the 247 has the same output shaft as the 242 and 231, which I think it does, you could use a slipyoke eliminator designed for either of them. The most affordable being this one:
https://www.ironrockoffroad.com/product/hack-n-tap-slip-yoke-eliminator-kit.html
I installed it on my 242 and its totally worth it.

[Canoe]

... a slipyoke eliminator designed for either of them. The most affordable being this one:
https://www.ironrockoffroad.com/product/hack-n-tap-slip-yoke-eliminator-kit.html
I installed it on my 242 and its totally worth it.

OMG What a site! It's like a candy store!

[Illeagle1984]

My go-to for drivetrain knowledge is Novak Conversions.  They do Jeep stuff mostly, but a lot of the information is relevant and they do mention Wagoneers.  A slip yoke eliminator kit is your best bet like Canoe said.  Here's a page on the different spline counts for the NP231/247:

https://www.novak-adapt.com/knowledge/np-nvg-input-gears

Looks like you get an easy match with the 247 because they're always 23 splines.  But I believe it says there are three different depths of the input gear?  I'm sure there's more than just the one page.  AMC Eagle: it might as well be a Jeep thing.

On a related note, what if I told you you could refill your viscous coupler?  I did mine Feb of 2019 and did about 3000 miles since in AWD the whole time.  It seems to be holding up well, though you might laugh if I told you what I used.

[TheBirdman]

Im more interested in how you sealed it up again afterwards

[Illeagle1984]

Well, I'll do a little writeup on it.  I did things a very specific way.  Short answer, though: diesel fuel and RTV.

Please let us know the gritty details on the swap when it comes time atmafox.  I want to see how you do the shifter.

[atmafox]

I'm actually cheating and not doing the shifter.  Wife fabricated up a plate to lock it in AWD.  Eventually I will do up a shifter so I can get at 4L but that's not a high priority.

[atmafox]

And re the linked SYE; the 247 has a hardened steel output shaft so tapping it is... Difficult to accomplish at best.  Thanks for the tip, regardless.

[TheBirdman]

Youre telling me a "mad engineer" cant mangle a carbide bit? As far as cutting it, I just put it in gear and started it up so the shaft rotated itself, then stuck an angle grinder on it. Given, my 242 was softer, but Ive cut hardened stuff with the deathwheel before and it doesnt seem like itd be a dealbreaker. Also correct me if im wrong, but isnt case hardening only a few mm thick at best?

[atmafox]

Ok, discussion of an SYE aside; the wife did some test fitting of the NP247 to the T5 that's eventually going in and it fits nicely, so I think I got lucky and got the right length input shaft on my 247.

Next up for research: the 247 doesn't have a mechanical speedometer gear.  So considering options like a GPS backed speed sender, anyone know if the AMC key size and turns per mile on the speedometer side are shared with Chrysler?

[TheBirdman]

I cant say for sure but I think the turns per mile is probably the same as chrysler since they use the same speedometer gears.