Not your papys np 242

Ponty56

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Joined
Aug 17, 2020
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2740
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7
So, I stumbled across this article and its something I've been thinking about for quit some time.

https://www.fourwheeler.com/how-to/...2-hd-np242-transfer-case-build-super-duty-np/

I drive a wj daily and love the options for the 242 transfer case and use 4wd full time quite often as i live in the midwest snow belt. I'd like to discuss with yall and try to compile some kind of parts list to do this very build as this article is somewhat vague as to what was used completely. As i understand it they discuss using the 6 pinion planetary gearset from the hummer 242 as well as the wider chain. Thus I would also need the driven and drive sprockets. I believe they also suggest that they use the 32 spline input from the hummer case. That is as far as I read that they used from the hummer case, and then they go on and discuss using the tom woods sye that is also 32 spline. What other components from the hummer case would be needed to do this? Does anyone have a good source to locate these parts individually without having to buy a complete case to tear appart?

This will eventually become a case in a new build down the road i only reference my wj as knowledge of using a 242. The new jeep will be a wrangler with a 5.9 magnum 545rfe and this hybrid of sorts transfetransfercas 05+ superduty axles. Need a jeep that can be used as a daily driver on a 40" tire. Also capable of wheeling and towing. With room for a family of 4.
 
They did NOT use the input shaft from the HMMWV since it doesn't match the Jeep transmission (32 spline vs 23 spline), and that is why they needed the Tom Woods 32 spline slip yoke eliminator to get the stronger output as opposed to doing the "hack and tap" slip yoke eliminator on the stock output. I have no idea if anyone still makes a NP242 32 spline slip yoke eliminator. However, If you were to use a chevy powertrain, you could use the HMMWV input, or if you where willing to run a chevy powertrain and live without 2WD (full-time 4WD) you could simply run an unmodified HMMWV case.
 
As I understand it, the output shaft is all they took from H1's NP242. I believe most, or all, NP24x transfer cases came with 6 pinion planetary gear sets.

I see there are 32 spline SYE kits for the NP242J, spendy at ~$500.
One thing though, have anyone actually snapped a 27 spline output shaft... meh
 
Id like to be able to use 2wd as well as all the other ranges, so it sounds like then all I would need is the planetary the drive and driven gears and the chain. Tom woods still makes the same sye kit. I'll be using a 545rfe transmission that was also used in the wj. But im also entertaining the idea of building an ecobox from nwf....
 
Don't do it!

First of all, the "full time" mode of the 242 literally the worst that exists. Its an open diff which will easily leave you stuck with one tire spinning. Been there, done that. If you must have full time then Quadra-Trac and Quadra-Drive are far superior systems.

The proper transfer case for the build you describe is an NV 241 or an Atlas. And yes, you can live without full time. Hear me now, believe me later.
 
Eric said:
Don't do it!

First of all, the "full time" mode of the 242 literally the worst that exists. Its an open diff which will easily leave you stuck with one tire spinning. Been there, done that. If you must have full time then Quadra-Trac and Quadra-Drive are far superior systems.

The proper transfer case for the build you describe is an NV 241 or an Atlas. And yes, you can live without full time. Hear me now, believe me later.
Click to expand...

But ti should work just fine for a Desert racer with a spooled rear. Iirc, 4 low will lock the center diff?

Otherwise yes I run fulltime 4wheel on my XJ during the winter and it holds up fine.
 
Weasel said:
But ti should work just fine for a Desert racer with a spooled rear. Iirc, 4 low will lock the center diff?

Otherwise yes I run fulltime 4wheel on my XJ during the winter and it holds up fine.
Click to expand...

Yeah i agree my 242 has 225,xxx+ on it as we speak and it has never left me stranded.
 
Eric said:
Don't do it!

First of all, the "full time" mode of the 242 literally the worst that exists. Its an open diff which will easily leave you stuck with one tire spinning. Been there, done that. If you must have full time then Quadra-Trac and Quadra-Drive are far superior systems.

The proper transfer case for the build you describe is an NV 241 or an Atlas. And yes, you can live without full time. Hear me now, believe me later.
Click to expand...

I fully intend on having selectable lockers in the axles at some point when budget allows.
 
Ponty56 said:
I fully intend on having selectable lockers in the axles at some point when budget allows.
Click to expand...
Lockers in the axles is a separate topic. Even with lockers in the axles full time mode of the 242 will send power to just the front or just the rear in low traction situations (and especially when starting from a stop). Its just a shitty full time system from the get go.
 
What Eric is saying is correct. Even with lockers it will allot the transfer case to slip which sorta messes up the point of a locker. For a wheeler I don't think it;s the way to go.
 
I completely understand now what your speaking of, but you think that using full time only in on road type situations would do this? Like I said i use it every winter season in my current vehicle with 225,xxx+ miles never let me down. In offroad type situations I'd only use 4wd high or low options.
 
ok, id like to get back to the topic at hand. Ive found the hmmwv driven and drive sprockets as well as the chain and ive also found the front output. these i know from reading are all compatible and stronger than the jeep versions. Also i have read that the hmmwv 6 pinion planitary was only designed for low speed type aplications so i think i will stick with the 242HD model 6 pinion planitary option for this upgrade. Tom woods does in fact still sell the sye so that covers the rear output. What i would like to know is can i use the heavier 32 spline input from a 241 in this case as it looks like there are several transfer cases that use the same planetary gear set?

https://www.transmissionpartsdistrib...uipment-17869/
 
Ponty56 said:
ok, id like to get back to the topic at hand. Ive found the hmmwv driven and drive sprockets as well as the chain and ive also found the front output. these i know from reading are all compatible and stronger than the jeep versions. Also i have read that the hmmwv 6 pinion planitary was only designed for low speed type aplications so i think i will stick with the 242HD model 6 pinion planitary option for this upgrade. Tom woods does in fact still sell the sye so that covers the rear output. What i would like to know is can i use the heavier 32 spline input from a 241 in this case as it looks like there are several transfer cases that use the same planetary gear set?

https://www.transmissionpartsdistrib...uipment-17869/
Click to expand...

Are you planning on changing to a 32 spline transmission? I have a hard time believing that there is a difference between the HMMWV planetary and the 242HD planetary.
 
'84 Bronco II said:
Are you planning on changing to a 32 spline transmission? I have a hard time believing that there is a difference between the HMMWV planetary and the 242HD planetary.
Click to expand...

I'd like to use the nwf ecobox underdrive unit in front of this so I can go with 32 spline for this connection. I intend on using the Chrysler 445/545rfe transmission as I already have one. I know that transmission is only a 23 splined output so if there are no upgrade options there I will be forced to keep that connection to 23 spline. I havent found if there are any upgrades on that front yet, still reading. Somewhere in my reading yesterday I came across an article that discusses at some point amg updated their version of the military 242 for strength concerns and that particular planetary was for only low speed applications. Not that it is any issue as the normal 6 pimion planetary that I liked above i also read somewhere yesterday is rated at something like 5,xxx ft lbs. With the ecobox at 2.72 ratio and the np242 at 2.72 low were talking a combined 7:4.1 low, should be plenty for my needs with all the other options of the np242.
 
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