Transfer case question

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Octane

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Not that this is definitive proof, but I do not believe the above is accurate.

This article mentions things I have always heard and experienced.

For what its worth:

https://www.fourwheeler.com/how-to/47538/
My manual says I have an interaxle differential in the 203 and when not in lock it is 50/ 50 split power between front and rear axles.When locked it is equal power to front and back axles.That is why in lock it jerks around when you turn the steering on dry pavement But not in regular hi or lo range.
 

Turbo4whl

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Some more information about how a differential works in a moment, but first your Full time 4 wheel drive. When you are in the unlocked position, on a dry road going straight, all four wheels are driving. All 3 differentials are not spinning the spider gears inside. All four wheel are traveling the same speed. As you make a turn, all four wheels are now traveling at different speeds. This is because the circle that each wheel travels through is a different diameter. In a left hand turn the right front wheel travels in the largest circle. Right rear the next largest circle, then left front and the left rear has the smallest circle to travel through. This is why you need a differential in each axle and one more between the two axles.

Differentials have 2 side gears inside and either 2 or 4 spider gears. The side gears are larger and have twice as many teeth as the spider gears. The side gears drive the axle shaft, one for each wheel. When the wheels need to travel at different speeds, (side gears need different speeds) they spin around the smaller spider gears. This way you have a smooth operation when turning the vehicle. The problem is the power moves to the wheel with the least amount of traction. So if you have limited traction, or more power as accelerating the wheel on the inside of the turn (smallest circle) ends up loosing traction and spins.
 

Turbo4whl

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There is only one differential in the transfer case. It only effects the rear axle. The front axle is always driving. When you shift to lock, that one differential is locked, then both axles are driving.


Not that this is definitive proof, but I do not believe the above is accurate.

This article mentions things I have always heard and experienced.

For what its worth:

https://www.fourwheeler.com/how-to/47538/


The reason I said the front is always driving is because the front has total larger circles to move through in a turn. With the greater distance the front axle becomes the path of least resistance. As stated in a differential, the power follows the path of least resistance.

Still true though, remove either front or rear driveshaft, in the unlock position the truck will not move.
 

75gmck25

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All the above explanations are basically correct, but I think folks get confused about how all the differentials work.

- All RWD vehicles have a differential in the rear so that the wheels can easily run at different speeds to go around corners. Some may also have the Gov Lock option to increase traction, but that's another discussion.
- If you have a front axle (like a square body 4WD) it has the same type of differential for the front wheels.

When you add a transfer case in the middle you now have the possibility of the the two driveshafts running at different speeds. With standard 4WD (NP205, etc.) this means you either have to be on a slippery surface (mud, snow, etc.) to allow for the different speeds, or you need to leave it in 2WD.
If you use a stock NP203 it also has a differential in the transfer case, and that allows the front and rear driveshafts to run at different speeds, so you can run in on pavement and leave it in "Hi" or "Lo". However, if you put it in "Hi Loc" or "Lo Loc" it locks the transfer case differential so that both driveshafts run at the same speed, and then operates similarly to the NP205. The Loc positions should not be used on hard surfaces.

If you convert an NP203 to part-time operation you would use one of the kits that replace internal pawls or the internal shaft to disable the differential capability so that the Hi and Lo positions are now 2WD and Hi Loc and Lo Loc are 4WD. However, when in 2WD position you don't get full oil circulation through the transfer case, so you are supposed to run it in 4WD about once a week to ensure full lubrication. AFAIK the NP203 internal shaft conversion kit is no longer produced, so the lighter duty pawl kit is the only one available.

Bruce
 

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The reason I said the front is always driving is because the front has total larger circles to move through in a turn. With the greater distance the front axle becomes the path of least resistance. As stated in a differential, the power follows the path of least resistance.

Still true though, remove either front or rear driveshaft, in the unlock position the truck will not move.

Well reasoned, Sir !

:)
 

Octane

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I hate people who brag! ! LOL
I am only getting 7.
The tires that was on mine before and the state of the tuneup I was getting 8 or 9 mpg once before.But I put my tuneup expertise,lol, on it and taking the old tires off my mpgs went to 12.
 
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So if I need to run in 4x4 in the snow then what would the proper procedure be? Shift into hi or hi loc? Do the front hubs have to be locked in then or leave unlocked?
 

Octane

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So if I need to run in 4x4 in the snow then what would the proper procedure be? Shift into hi or hi loc? Do the front hubs have to be locked in then or leave unlocked?
Fulltime dont have locking hubs.If you need to.... run in any way that works best for the ground conditions
 

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In marginal traction conditions I'd go to Hi Lock. Otherwise you effectively have one-wheel drive.
 

Bill Tolrud

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Another thing to consider if changing the NP203 from full time, the NP203 is oiled by the chain if the unit is not turning the front axle it does not get oiled. You should shift to 4 wheel drive every so often to ensure the transfer case is well lubed.
 

Nine

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Kevin,

I have a converted 203 in my 73. It works great. On my 203 one down from N is 2H, two down from N is 4H. One up from N is 2L. Two up from is N 4L.

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Kevin,

I have a converted 203 in my 73. It works great. On my 203 one down from N is 2H, two down from N is 4H. One up from N is 2L. Two up from is N 4L.

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what position do you put the shifter in when you drive it?
 

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