# Offroading stuff



## NaeKid (Oct 17, 2008)

TiredIron and I were talking about building up some stronger offroad vehicles and we got onto the topic of the NP203 and NP205 transfer cases and doing the twin-stick conversions on them.

There is an adapter-plate that allows the front of an NP203 to mount to an NP205 and allow you to have a doubler - or double-low gearing.

http://www.offroaddesign.com/catalog/doubler.htm



> *Doubler™ Quick Facts and FAQ answers*
> 
> Gear reduction of NP203 gearbox: 2.01:1
> Gear reduction of NP205: 1.96:1
> ...


Picture of the doubler assembled.


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## Tirediron (Jul 12, 2010)

I have never looked into this set up before, but that isn't much longer than a stock 203,:scratch


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## Tweto (Nov 26, 2011)

I'm not sure what you want from this. And then why put it behind a TH400 (very good transmission).

I had a 74 Ford F-250 with a four speed manual with granny low and a divorced transfer case with low four wheel drive. I loved having the ability to pull stumps with it but it would only go about 10 MPH at 3000 RPM. I could use it like a farm tractor. When I drove it normally, I never ever used the low four wheel drive or the granny low on the transmission. 

So instead of using the TH400 just put in a heavy duty T-10 transmission and you have the same thing. Or am I getting your original idea of making a stronger vehicle wrong?


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## NaeKid (Oct 17, 2008)

Tirediron said:


> I have never looked into this set up before, but that isn't much longer than a stock 203,:scratch


It takes away about 8" from your rear-drive-shaft and adds about the same 8" to your front driveshaft. You could say that it makes the NP205 longer by 8" which is something I cannot do to my Jeep (my poor rear drive-shaft is way too short as it is).

The thing about doing this is that you can flip the NP203 into low-range and then the NP205 would be low-range 2WD (rear-wheels). Or, you could flip the NP205 into 4-low and leave the NP203 front in high-range and the NP205 acts normally. Pull the lever on the NP203 and then you have DoubleLow going to the axles.

Crawling up rocks, moving boulders and logs and such would be child's play in double-low. Your rig that you have in your backyard could go from mud-bogger in high-range to stump-puller in 2.3-seconds flat. Just imagine some of the cut-lines in Waiparous and how steep they are. Then put an anchor on the back of your rig (a friend with a blown axle) and pull him up. Leave the truck in idle and it will still reach the top!

An SM465 transmission with granny-low combined with that doubler would be amazing!


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## Boomy (Mar 17, 2012)

Rock crawler tech. I knew a guy with a Suzuki Samurai that had deuce and a half axles rolling 48"s powered by the original 4cyl.
Gearing can make a difference..


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## hashbrown (Sep 2, 2013)

I'm running a np 203 with a dana 300 doubler the dana 300 has a lo max 4/1 kit twin sticked. I have been using this set up for 3 years and it has held up under hard wheeling. Front digs and any type of gearing you want with this setup.


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## helicopter5472 (Feb 25, 2013)

Tweto said:


> I'm not sure what you want from this. And then why put it behind a TH400 (very good transmission).
> 
> I had a 74 Ford F-250 with a four speed manual with granny low and a divorced transfer case with low four wheel drive. I loved having the ability to pull stumps with it but it would only go about 10 MPH at 3000 RPM. I could use it like a farm tractor. When I drove it normally, I never ever used the low four wheel drive or the granny low on the transmission.
> 
> So instead of using the TH400 just put in a heavy duty T-10 transmission and you have the same thing. Or am I getting your original idea of making a stronger vehicle wrong?


I tend to agree with you... Older Trucks All 3 American ones used to use a 4 speed with 1st being a "granny" low. They were geared low enough to pull any stump that the combination above can do. If you can't get the traction, doubling the low gear won't help you. Even with front and rear lockers. If you want to pull stumps get a 5 ton military you not only have the gearing, the extra axle and the weight. BUT if you want a new toy with extra levers to play with, that is a slick setup. Thumbs up.


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## hashbrown (Sep 2, 2013)

helicopter5472 said:


> I tend to agree with you... Older Trucks All 3 American ones used to use a 4 speed with 1st being a "granny" low. They were geared low enough to pull any stump that the combination above can do. If you can't get the traction, doubling the low gear won't help you. Even with front and rear lockers. If you want to pull stumps get a 5 ton military you not only have the gearing, the extra axle and the weight. BUT if you want a new toy with extra levers to play with, that is a slick setup. Thumbs up.


I was always a fan of a 5 ton until I owned one. In my opinion pulling stumps is about all they are good for. If I would have to choose from a 5 ton and a simple locked jeep for my purpose I would choose the jeep every time. If you are handy with a welder and have any sort of mechanical skill you can build yourself a machine that no factory built vehicle stands a chance of keeping up with.


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## Tirediron (Jul 12, 2010)

1 st low might be deep enough for a pick up with stock tires, but a dual wheel truck without deep rear end gears can use more reduction. for stump removal a D8 with a root rake works pretty nice


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## LincTex (Apr 1, 2011)

Tweto said:


> I had a 74 Ford F-250 with a four speed manual with granny low and a divorced transfer case with low four wheel drive. I loved having the ability to pull stumps with it but it would only go about 10 MPH at 3000 RPM. I could use it like a farm tractor. When I drove it normally, I never ever used the low four wheel drive or the granny low on the transmission.


Same here. NP435 granny low and NP205 is a STOUT low-range combo. ESPECIALLY with a 4BT3.9L Cummins in front of it, you *ain't gonna* stop that thing!

My first thoughts:

1) lack of traction - all that torque still needs to make it to where the rubber meets the dirt. If that contact patch fail, more torque doesn't help.
2) if you have enough traction - can your axles handle that much torque? probably not.

3) this would be a bitchin' set-up for someone making a homemade 4WD tractor!


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## Tirediron (Jul 12, 2010)

I exploded a np205 output shaft in a Chevy DRW with a service body on it, I was pulling a crane that the trans had failed in, if I would have had more reduction, I could have moved it just off idle, as it was I hit the end of the strap in low range 1 st gear (sm465) at about 1500 rpm, the crane moved about 2 feet but the 454 had more torque at that speed than the output shaft could handle, what a bang when the shaft let go. A little less traction and I wouldn't have added another "you can't break that" part to my list, 
6.5 detroits are no slouch for off idle torque either


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## hashbrown (Sep 2, 2013)

mike_dippert said:


> Ive always felt like doublers were more for underpowered rigs. 4cyl Yotas and zukes running 35+ tires. They can gear the axles for street type use, but have that super low granny gear for the rocks.


Lol some of those with a sick underpowered 4.0 could use a doubler as well.....


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## Boomy (Mar 17, 2012)

The 4.0s aren't that bad compared to the anemic 3.8 the put in my JK.
I wish I had my 4.0 from my Cherokee or a 4.3 Chevy.


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