Humvee Cummins and Overdrive

[coggonobrien]

I am considering buying a milsurp Humvee. Is there anybody here or a resource off here that has done a 5.9 cummins swap with an overdrive transmission? Just curious what the towing and highway manners ended up being.

Thanks!

 

[simp5782]

Not good for towing as it is a HMMWV. It weighs about as much as an F-150. so you aren't moving much.

Google search " 5.9 cummins HMMWV " and you will have endless links to content involving that mod.

 

[Skrilex]

I wish it was endless but it seems only a few have done it with documentation. Anyway I’m gearing up to do a 12v with a 47rh overdrive trans. Wish me luck!

 

[Skrilex]

One of the big questions is if I will be able to retain AWD with the 47rh. I’d like to keep AWD but if I can’t then a different t case will suffice. Having an intercooled turbo 5.9 will be a huge upgrade for the old m998.

 

[tage]

Uh, good luck?

 

[tage]

One of the big questions is if I will be able to retain AWD with the 47rh. I’d like to keep AWD but if I can’t then a different t case will suffice. Having an intercooled turbo 5.9 will be a huge upgrade for the old m998.

do you mean th400? cummins adapter plate to the th400 would probably be the easiest route. when you have a complete power train swap, and the 47RH is making sure the transfer case drop is on the correct side. New transmission mounts, drive shafts, ect. AWD is relative. you mean keeping it 4wd vs 2wd? full time vs part time transfer case is the real question here. you can't really go outside, and lock some hubs on a hmmwv. lol

Personally I would go with the NV4500 if I was to swap out my 6.5 optimizer with a cummins. Chance of that happening slim to none though. Keep it original. way cheaper.

 

[Skrilex]

No I want to use the 47rh that came with the cummins. It’s a decent trans and has a good overdrive. The th400 doesn’t have overdrive.
I mean awd as in, well, maybe I’m using wrong term, but to me a center differential 4wd is better described as AWD. Then when center locked it’s 4wd. Hmmwv does not offer a 2wd mode, but some people choose to change to that instead of awd because most transfer cases offer this mode instead. Nothing wrong with that, and I actually prefer to drive 2wd on the street, but if my cummins is pounding the drivetrain I’d rather it pound evenly over 4 tires than 2.

 

[tage]

then you want a full time transfer case. NP203 comes to mind.

 

[coggonobrien]

pardon my ignorance, is a stock milsurp hmmwv all time 4x4?

 

[Skrilex]

Not sure about all but all hmmwv but I believe most have 3 basic drive modes, normal mode is a type of AWD with 52/48 split between from and rear, true 4wd which they call HL and a true 4wd low range they call L.

 

[Skrilex]

then you want a full time transfer case. NP203 comes to mind.

Why not try to keep the stock np242?