NP203, NP205, NP208 Differentiating Power to front and rear axles.

[oneluckypops]

I have never heard of any 70/30 split mentioned before. I do know that even when out of the truck, if a 205 or 208 are shifted into 4lo/hi and you turn the input by hand, both outputs turn the same amount. I have also seen all the guts of a 205, there's no diff that I'm aware of.

The only good use of a 203 (IMHO) is for the use of a doubler setup. They are big, heavy, and the shifter sucks big time.

I hope so. As a matter of fact, it was a Newbie on here that was looking for a Jeep Tcase for his Square I do beleive. He was the one saying, NP205 and 8 do not send equal power to the axles, so he wanted to find this Jeep Tcase. That's what I understood anyway. I'll see if I can find the thread.

They send the same amount of torque to the fron and rear differentials, IF it was true about differnt ratios to the front as the rear then you would HAVE TO run different gear ratios from the fron to the rear differential, otherwise you would blow the case apart.

A NP203 Transfercase has to have both front and rear driveshaft installed or the truck will free wheel, the ONLY way you can run with out the front driveshaft is to lock it in 4 HI LOC. If anyone wants to doubt this then by all means, I will send you my medical bills all 25,000 dollars of them from when I learned this the HARD way.
EDIT; which is another reason I am willing to sell the NP203 so cheap it nearly cost me my life.

 

[crazy4offroad]

In this exploded view there is a differential (think posi or similar diff), looks VERY similar to the spider cross in a 14-bolt diff, that when the rear slips the front kicks in...
http://www.offroaders.com/tech/Diagrams/ford-np203.jpg
I had always heard Jeep elitists brag that their fulltime t-case was 50/50 and GM was 60/40 or so, looking back I guess they were comparing their best to our worst!

 

[89Suburban]

They send the same amount of torque to the fron and rear differentials, IF it was true about differnt ratios to the front as the rear then you would HAVE TO run different gear ratios from the fron to the rear differential, otherwise you would blow the case apart.

A NP203 Transfercase has to have both front and rear driveshaft installed or the truck will free wheel, the ONLY way you can run with out the front driveshaft is to lock it in 4 HI LOC. If anyone wants to doubt this then by all means, I will send you my medical bills all 25,000 dollars of them from when I learned this the HARD way.
EDIT; which is another reason I am willing to sell the NP203 so cheap it nearly cost me my life.

I pulled rear shafts and ran around in HI LOC like a front wheel drive. I also pulled and replaced 3 of those 203's replacing transmissions on my old Dodge's, they are a very heavy, and awkward sumbitch to handle. I don;t miss them.

 

[smurph20]

Its not a 203 i know that but my Grand Cherokee is the same way if you remove a shaft it will roll in park. It has a viscus coupling in it i think it was its called and if you run it without the front or rear shaft for long periods of time it will burn the coupling up and wont pull at all. Thats the only bad thing i can find with my Grand is that its full time locked in 4x4 it only has 4HI and 4LO.

 

[sean1960]

They send the same amount of torque to the fron and rear differentials, IF it was true about differnt ratios to the front as the rear then you would HAVE TO run different gear ratios from the fron to the rear differential, otherwise you would blow the case apart.

It is true, the 203's have an open differential in the rear bearing housing. The 30-70 split is apparently just an old wives tail. I just did a little research on 203's and the only reference to the 30-70 split is on other forums. The New Process transfer case charts I found list it having an open differential. However I would like to add that you would NOT have to run different gear ratios from front to rear if the differential were like a limited slip and I don't know why they didn't make them like that.

 

[bucket]

...if the differential were like a limited slip and I don't know why they didn't make them like that.

It would be a hot setup if they did. I wonder if it would be possible to design a limited slip unit for it?

 

[89Suburban]

They send the same amount of torque to the fron and rear differentials, IF it was true about differnt ratios to the front as the rear then you would HAVE TO run different gear ratios from the fron to the rear differential, otherwise you would blow the case apart.

A NP203 Transfercase has to have both front and rear driveshaft installed or the truck will free wheel, the ONLY way you can run with out the front driveshaft is to lock it in 4 HI LOC. If anyone wants to doubt this then by all means, I will send you my medical bills all 25,000 dollars of them from when I learned this the HARD way.
EDIT; which is another reason I am willing to sell the NP203 so cheap it nearly cost me my life.

So what happened man? Did it roll over you?

 

[82chevy350]

So which case is better?
My dad insist that i rebuild my np203 instead of trying to find another 203..
Im really leaning towards finding a 205 or 208 what do yall think?

 

[crazy4offroad]

Install an NP205 and then forget it. King Bulletproof.

 

[Christian Nelson]

I like the concept of the 203, but like was said earlier, if one could add a posi, or locking set up to it, it would be AWESOME..

I used to just put locking hubs on my old truck, and drive it in Hi lock all the time, cornered without all that feeling with the axles deciding which one was spinning faster thing that they do.

But, for ice and snow it was nice to be able to drive it with the lockouts locked in in HI, and be able to drive on the freeway without worry.

ONly complaint I had was when I found out the hard way that my rear brakes weren't grabbing at all, and I slammed into and over the hood of an unsuspecting caddillac in a parking lot when I tapped the front brake in the turn on some ice.

You all know what happens when you stop one side of a differential, right? The other side spins, well, my front wheels locked right up on that ice, and my rears shoved me in a straight line right onto the top of the hood of that poor car..

THat SUCKED..

I found that the previous owner had in their wisdom decided they didn't need no rear brakes and had just plugged the rear line rather than replace it when the rubber one broke.

Would have been nice to know, I had just gotten the truck..

Now, I look at my brakes and stuff on a new vehicle religiously..

That was one expensive lesson to learn. I felt so bad for the owner of that nice caddy, it was a late 60's in beatiful shape, no idea why he had it out on a January snow day, but that still doesn't excuse me for wrecking that thing.

 

[Mike D]

Without rear positraction the RR and LF tires did the pulling on pre 88 Chevy trucks. On 88 - current (?) the RF and RR do the pulling. This later set up would reduce torque steering when the vehicle is in 4wd and turning on pavement.
Several years ago I read someware the power is split 30% front / 70% rear. Probably because the front wheel locking mechanisms would break if too much power is applied.

 

[oneluckypops]

So what happened man? Did it roll over you?

Yes it did.

I was in a huryy one day to go fishing, well my front driveshaft had alot of vibration it it. So i was gonna have my dad re weld the yoke on before I went. I pulled up to the shop door, truck was parked on a hill didnt think to block the wheels, jumped under the truck and started pulling the bolts out of the front drive shaft. i got 3 bolts out and was taking the fourth out when I had about 3 threads left it broke. I was laying behind the FR Tire. I heard the pop sound and the next thing I know I am trapped under the front right tire. But instead of just going over top of me my body was like a wheel chock and the truck just kept rolling down the gravel driveway with me under the tire. I am not really sure how far exactly it slid me but when it finally went over me I was roughly 60-70 feet from the shop.

i can remeber getting up and trying to holler for help and I couldnt speak. I staggered up and tried to walk back to the house, when my uncle drove up circled around the circle driveway drove right past me and just kept going. When he went past me I collapsed and couldnt make it any farther. I later woke up with my dad over top of me and I could hear the sirens getting closer, then once in the ambulance i could hear them say something about life flight and thats all I could remeber after that.

 

[bucket]

Without rear positraction the RR and LF tires did the pulling on pre 88 Chevy trucks. On 88 - current (?) the RF and RR do the pulling. This later set up would reduce torque steering when the vehicle is in 4wd and turning on pavement.
Several years ago I read someware the power is split 30% front / 70% rear. Probably because the front wheel locking mechanisms would break if too much power is applied.

Not trying to be rude, but that info is bogus. There's no way to force one tire to get more power than another. If it's posi, both get equal power. If it's non-posi, both get equal power until one slips, then the slipping tire gets all the power. Torque steer is not a concern on a 4x4 truck... you aren't supposed to run 4x4 on pavement.

And again, you can't have a 70/30 power split if the T-case doesn't have a differential in it. And the locking hubs can handle full power.

 

[bucket]

Yes it did.

I was in a huryy one day to go fishing, well my front driveshaft had alot of vibration it it. So i was gonna have my dad re weld the yoke on before I went. I pulled up to the shop door, truck was parked on a hill didnt think to block the wheels, jumped under the truck and started pulling the bolts out of the front drive shaft. i got 3 bolts out and was taking the fourth out when I had about 3 threads left it broke. I was laying behind the FR Tire. I heard the pop sound and the next thing I know I am trapped under the front right tire. But instead of just going over top of me my body was like a wheel chock and the truck just kept rolling down the gravel driveway with me under the tire. I am not really sure how far exactly it slid me but when it finally went over me I was roughly 60-70 feet from the shop.

i can remeber getting up and trying to holler for help and I couldnt speak. I staggered up and tried to walk back to the house, when my uncle drove up circled around the circle driveway drove right past me and just kept going. When he went past me I collapsed and couldnt make it any farther. I later woke up with my dad over top of me and I could hear the sirens getting closer, then once in the ambulance i could hear them say something about life flight and thats all I could remeber after that.

Dang! That had to SUCK.

 

[oneluckypops]

Dang! That had to SUCK.

yes it did, the hole right side of my body from my waste to my arm pit was hamburger from the gravel. You could also see the tread from the sport king tires across my back for several weeks.