What transfer case do I have?

[Agelai]

What transfer case do I have?
Hmmwv M1025A2

I find people saying it's 3-4 different ones.

 

[Coug]

NP242 should be the only one used in A2 trucks.

The parts manual clearly shows that for your truck (Usable On Code C17) uses NSN 2520014092512 for the transfer case.
That transfer case comes up as the NP242 when searched.

all the manuals for your truck are posted here, and the parts manuals end in -24

TMs for the M998-Series HMMWV

Listed below are a number of the TM's for the M998 series trucks. To save them to your computer, right click, select "save as". TM-9-2320-280-34.pdf TM-9-2320-280-34 Direct support and general support maintenance for the M998 series trucks. TM-9-2320-280-20-1.pdf TM-9-2320-280-20-1...

www.steelsoldiers.com

 

[Retiredwarhorses]

What transfer case do I have?
Hmmwv M1025A2

I find people saying it's 3-4 different ones.

that’s the internet for ya…late 242

 

[Agelai]

yeah and these forums sometimes get a little crazy with random information spread out into 37 treads.

I want to try and find a rebuild kit for this, so I'll start my searching on the NP242.
I'm also looking for the gear selector for this, we shall see what I can find.

 

[Agelai]

Has anyone replaced the transfer case selector lever with a single unit?
Like a standalone

 

[Vapor Trail]

I'm confused. When I googled NP242 it says selectable 2 and 4 WD but I thought HMMwvs were all time all wheel drive which is the duty of the transfer case so which is correct?

 

[Coug]

I'm confused. When I googled NP242 it says selectable 2 and 4 WD but I thought HMMwvs were all time all wheel drive which is the duty of the transfer case so which is correct?

hmmwv is full time 4wd.
There are civilian versions that are selectable.
The military version is not.

The Novak Guide to the New Process / New Venture Gear 242 Transfer Case

The Novak Guide to the New Process / New Venture Gear 242 Transfer Case

www.novak-adapt.com

 

[Milcommoguy]

Full time slip with lock up... low or hi.

Climb under and read the tag on the back of TC. The little round one, about the size of a silver dollar.

Everyone doing all the work tired me out, CAMO

Something to read > https://static.e-publishing.af.mil/production/1/af_a4/publication/qtp24-3-l530/qtp24-3-l530.pdf

 

[Mullaney]

Full time slip with lock up... low or hi.

Climb under and read the tag on the back of TC. The little round one, about the size of a silver dollar.

Everyone doing all the work tired me out, CAMO

Something to read > https://static.e-publishing.af.mil/production/1/af_a4/publication/qtp24-3-l530/qtp24-3-l530.pdf

.
Gee... That is a "-10" TM on steroids. 8 hours worth of training time before you get cut loose with one. Hmmm. Almost wonder if the auction houses wouldn't do the world a favor if every buyer got one of these with their truck.

Put it in the air filter box - wedged against the intake - so it had to be seen. Bright yellow cover with READ ME on the outside of the book.

 

[Agelai]

Yeah this is where I get a little confused, on the hmmwv the lever indicators are HL, H, N, L and a regular truck 2H, 4H, N, 4L

 

[Mogman]

Yeah this is where I get a little confused, on the hmmwv the lever indicators are HL, H, N, L and a regular truck 2H, 4H, N, 4L

The HMMWV has "full time FWD" in H it is driving both axles through a DIFFERENTIAL in the transfer case meaning in H you could jack up ether end and not go anywhere, similar to an open differential in a rear end, if you jack up one wheel it will not go anywhere but in "normal" operation it is siad to be driving both wheels. in HL it bypasses or "locks" that differential so it is pulling on both axles, same in L only the transfer case is also using a gear reduction at that time.
The reason even an "open" differential automatically tries to bias power to both of its outputs is because just like the rear end if you spin one wheel only it will be turning twice as fast as it would be if both wheels were turning., just the way a differential works.

 

[Mogman]

READING..

Gearhead 101: How Full-Time 4WD and All-Wheel Drive Work

Full-time 4WD and AWD have all four wheels moving the car all the time. But how do these drivetrain systems do that?

www.artofmanliness.com

.

 

[Mogman]

Then of course you have "automatic" 4WD or 6WD like the M35, it uses a rather ingenious setup, the front diff has a slightly different gear ratio than the rear diffs. so under normal operation (on pavement for example) the front driveshaft is turning slightly faster than the rear driveshaft, the front output in the transfer case has an overrunning clutch (sprag) so under normal operation because the front shaft is turning faster then the rear there is no power going to the front shaft as it is simply "overrunning" the rear shaft.
Now when the rear tires start to slip and the rear shaft tries to turn faster than the front shaft due to slippage the sprag clutch locks up and you have automatic 6WD.