NP242 Question

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Jon1097
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NP242 Question

Post by Jon1097 » Mon Jun 15, 2009 10:42 am

What are the differences between the military and civilian NP242? I have a civilian 4l80e and there's a civilian np242 on epay for sale ($400). I was planning on going 24v with my wiring but was curious on the civilian and military differences. Thanks. -Jon.
1- Pile of Humvee Parts


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Re: NP242 Question

Post by doberer » Mon Jun 15, 2009 11:11 am

I am elbow deep in rebuilding 2 NP242 cases and here is what I found so far. I am converting 2 military spec ones to civi style...

The military has 24v switches
The military case, while having the same casting New Venture part number doesn't have the T/C switch drilled into it (near the coolers)
The retainer piece is different
The civi uses a tone ring and the military uses a purple worm gear thingy
Otherwise I compiled a really exhaustive list of all the parts and just about all the internals are the same
I am sure I am missing something but I am about 3/4 of the way thru the teardown and parts list. I know Brad converted a civi to milspec case for his A2 truck.

I also found that the military used 2 different NP242 transfer case designs, the A1 and A2. The A1 has 27 splines and the A2 used 32 (same as the civi). the housing and shafts are different. Also the civi transfer case was beefed up after 96 so watch for the year you have.

If you have any other questions let me know. Also unless that $400 is is really good shape you will burn about $400 in parts to fix it back up (w/o major shafts and planetary changes). you can get a rebuilt one for $1000 on the web.

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Re: NP242 Question

Post by Action » Mon Jun 15, 2009 1:54 pm

Did you use a spreader to get the parts out of the casing?

Jason

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Re: NP242 Question

Post by doberer » Mon Jun 15, 2009 2:49 pm

Action wrote:Did you use a spreader to get the parts out of the casing?

Jason
didn't need a spreader, just removed all the snap rings. Isn't the spreader for the diff?

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Re: NP242 Question

Post by Clarke » Mon Jun 15, 2009 4:35 pm

doberer wrote:[SNIP]
The civi uses a tone ring and the military uses a purple worm gear thingy.......I also found that the military used 2 different NP242 transfer case designs, the A1 and A2. The A1 has 27 splines and the A2 used 32 (same as the civi). the housing and shafts are different. Also the civi transfer case was beefed up after 96 so watch for the year you have.
The tail-shafts are different to accommodate the speed sensor - the military tail-shaft has a much larger hole for the mechanical worm drive mechanism.

There was a upgrade to the t-case as mentioned where some of the internals and splines were changed around 95/95 on the civvie side. Any 97 and up Civvie with the right tail-shaft should work. There was a late 2000/2001 recall and mod to the civvie t-case cooling loop where the loop would crackand the dreaded "vampire" would strike - sucking the ATF out of the tranny. The mod added an additional mounting tab to the cooler loop to prevent vibration cracks. I don't know if the military loops got that mod too.

Cheers,

Clarke

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Re: NP242 Question

Post by Action » Mon Jun 15, 2009 6:04 pm

doberer wrote:
Action wrote:Did you use a spreader to get the parts out of the casing?

Jason
didn't need a spreader, just removed all the snap rings. Isn't the spreader for the diff?
Correct. My bad. I have been working on my diff lately. I guess I just carried that into this post not realizing it is the T/C. Oops.

Jason

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Re: NP242 Question

Post by ragman » Tue Jun 16, 2009 7:25 am

It may also depend on what era you are trying to match to. Some of the Special Forces trucks ran with the electronic speedometer which I thought required some of the civy parts.

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Re: NP242 Question

Post by Clarke » Tue Jun 16, 2009 1:23 pm

ragman wrote:It may also depend on what era you are trying to match to. Some of the Special Forces trucks ran with the electronic speedometer which I thought required some of the civy parts.
Based on the info that Brad posted when he found the sender for the electronic speedo's, the drive assembly uses the same tail-shaft athe mechanical speedo. Here is his post: http://www.g503.com/forums/viewtopic.ph ... ad#p780639

Cheers,

Clarke

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Re: NP242 Question

Post by dunsbr » Wed Jun 17, 2009 3:28 am

***UPDATE***
I found another speed sensor for the Humvee.
I picked one up on my last trip to the US.

I'll post some pic's of it (and part numbers) when I get back home on the weekend

Cheers
Brad Dunstan
RHD '87 M1026
(with 4L80E Trans, 242 T/case, 12K hubs, CTIS, A2 wiring, Air Con, A2 ebrake, 9k Winch,
Serpentine Belt Accessory Drive & Eaton e-lockers)

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Re: NP242 Question

Post by Clarke » Wed Jun 17, 2009 8:06 pm

dunsbr wrote:***UPDATE***
I found another speed sensor for the Humvee.
I picked one up on my last trip to the US.
Brad! You've been holding out on us.....


Cheers,

Clarke

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Re: NP242 Question

Post by dunsbr » Wed Jun 17, 2009 11:05 pm

Who me?!? :roll:

Cheers
Brad Dunstan
RHD '87 M1026
(with 4L80E Trans, 242 T/case, 12K hubs, CTIS, A2 wiring, Air Con, A2 ebrake, 9k Winch,
Serpentine Belt Accessory Drive & Eaton e-lockers)

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Re: NP242 Question

Post by dunsbr » Sat Jun 20, 2009 2:02 am

Hi Guys,

Here's the different type of HMMWV electronic speed sensor I picked up in the US on my last trip.

Cheers
Attachments
IMG00604-20090619-1735.jpg
IMG00604-20090619-1735.jpg (42.15 KiB) Viewed 2042 times
IMG00607-20090619-1735.jpg
IMG00607-20090619-1735.jpg (39.39 KiB) Viewed 2041 times
Brad Dunstan
RHD '87 M1026
(with 4L80E Trans, 242 T/case, 12K hubs, CTIS, A2 wiring, Air Con, A2 ebrake, 9k Winch,
Serpentine Belt Accessory Drive & Eaton e-lockers)

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Re: NP242 Question

Post by Clarke » Sat Jun 20, 2009 11:46 am

Could the pictures be any blurrier? :-)

How does it work? Gear drive or inductive? Is this an alternate part to what you posted before or a different setup to drive the electronic speedo?

Cheers,

Clarke

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Re: NP242 Question

Post by dunsbr » Sat Jun 20, 2009 8:18 pm

Hi Clarke,

Sorry, I took them in the workshop at night.

How are these?

Image

Image

Image

As you can see, the sender simply screws on to the standard military Humvee geared speedo drive in place of the cable.

Cheers
Brad Dunstan
RHD '87 M1026
(with 4L80E Trans, 242 T/case, 12K hubs, CTIS, A2 wiring, Air Con, A2 ebrake, 9k Winch,
Serpentine Belt Accessory Drive & Eaton e-lockers)

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Re: NP242 Question

Post by Clarke » Sat Jun 20, 2009 9:50 pm

Part numbers unreadable. :-(

Where did you get it? What about the harness up to the speedo?


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