Whoops! (4x4 on dry pavement)

[HotRodPC]

Not to steal this thread, But how bullit-proof is a 203?

Fairly strong units. They are a heavy as hell cast iron case. The 1 weakness is, it is chain driven. Chain can stretch with wear. But, the chains are also very strong, and it was never a common issue that the chain needed to be changed often. That would be the only weakness I"m aware of. Pretty stout units that will tolerate abuse.
The downfall of the unit and why many don't like to use it, is because it's a Full Time 4wd unit. Your choices are 4 Hi, 4 Hi Loc, N 4 Lo and 4 Lo Loc.

 

[Driver4r]

Well, in that case, i might put that part time conversion in it.

 

[HotRodPC]

Well, in that case, i might put that part time conversion in it.

Not so fast !!! I'm not going to claim to be the expert on the NP203, so anyone can correct me if I'm wrong. It's my understanding, the NP203 is a differentiating transfer case. So even though you're in 4HI, Not 4HI Loc, you still only have 1 wheel drive unless you have lockers or limited slip diffs. It'll work just like your rear differential will work without a locker. It will power the axle that has the least traction, just like a rear end will power the wheel with the least traction and that's how you get stuck. So as long as your wheels have traction it should just power 1 axle at a time, could be the front, could be the rear. This is why if you take the front driveshaft out, the truck won't move because its going to be easier to spin the front take off of the transfer case and that is what will spin. So you have to have both shafts in, or use 4Hi Loc, and keep both front wheels locked in. Point I'm making, the FULL time 4x4 is not as bad as having one of the other model transfer cases in 4HI all the time. Then when you'd use 4Hi Loc, then its like the other transfer cases in 4HI and it will run both axles and not differentiate the axles. The Part time has been known to have lubrication issues with this Tcase. So you must put it in 4Hi and drive it every so often to make sure it stays lubed. If it were me, I'd just leave it alone if I wasn't going to swap to another Tcase. As long as your in 4HI, I don't think it would be all that bad, and not worth the risk of tearing up your Tcase. And if you're that worried about it, I think the money towards a different Model Tcase would be better spent than doing the Part Time kit. But that's just the way I understand it to be, and that is my opinion. Hopefully another wheeler like C4 who knows better can deny or confirm for us.

 

[crazy4offroad]

NP203 is cast iron but forfeits its "bulletproof" status by being chain driven. It is a differentiating fulltime t-case, with what resembles an axle differential in the t-case. It doesnt take much throttle for the front axle to kick in though, you wont have any rear wheel spin before the front takes over, contrary to a "posi" in a rear axle that might let one wheel slip a little before the other kicks in. I agree the money spent on a part-time kit for the 203 would be money better spent on an all gear-driven NP205. Your rear driveshaft may be a couple inches short after the swap so you may want to grab that from the donor truck if that's how the case may be. Front shaft may need to be a couple inches longer so I would grab that as well.

 

[Driver4r]

Befor i bought my truch, it sat for 3-4 years. and befor it was parked, the transmission and tcase were rebuilt. Im not sure if it has the conversion in it, i can romp on it in high(not high lock) and break the back loose for quite a ways. Any ideas if you think its possible it has it in it?

 

[89Suburban]

Befor i bought my truch, it sat for 3-4 years. and befor it was parked, the transmission and tcase were rebuilt. Im not sure if it has the conversion in it, i can romp on it in high(not high lock) and break the back loose for quite a ways. Any ideas if you think its possible it has it in it?

If you can break the rear end loose like that then I would go out on a limb to say yes it has the kit in it. I had several vehicles with that full time case and I don't ever remember being able to do that.

Also a hard acceleration from a stop and turning tight at the same time you should feel some stress from the front knuckles trying to pull. Even thought it is not in 4Loc, you would still feel that slight wobble.

 

[bucket]

Befor i bought my truch, it sat for 3-4 years. and befor it was parked, the transmission and tcase were rebuilt. Im not sure if it has the conversion in it, i can romp on it in high(not high lock) and break the back loose for quite a ways. Any ideas if you think its possible it has it in it?

Has someone put manual hubs on it? If so, unlock them and put the truck HI (not HI Loc) and see if the truck can drive. If it will drive, it's been converted. If it hasn't been converted, the truck will act like you're in neutral.

 

[Driver4r]

yes i have a set of hub locks on it, and she drives great in 2wd.

 

[HotRodPC]

Befor i bought my truch, it sat for 3-4 years. and befor it was parked, the transmission and tcase were rebuilt. Im not sure if it has the conversion in it, i can romp on it in high(not high lock) and break the back loose for quite a ways. Any ideas if you think its possible it has it in it?

I"d say that's normal activity for a NP203. Remember it's a differnentiating Tcase if it's not in Hi Loc. In regular HI, it's going to send power to the axle with the least traction which is the rear since the front axle has the weight of the motor on it. It will be rare that the front axle has less traction than the rear. Get on some wet pavement or dirt , put your E brake on to the floor, then you should break the front wheels loose if it don't have the kit.

 

[HotRodPC]

yes i have a set of hub locks on it, and she drives great in 2wd.

If manual hubs are FREE and it drives, then it's been converted.

 

[89Suburban]

In regular HI, it's going to send power to the axle with the least traction which is the rear since the front axle has the weight of the motor on it. It will be rare that the front axle has less traction than the rear.

Maybe with a pickup truck. Not with a Burb or Ramcharger.

 

[guitarfreak235]

Not so fast !!! I'm not going to claim to be the expert on the NP203, so anyone can correct me if I'm wrong. It's my understanding, the NP203 is a differentiating transfer case. So even though you're in 4HI, Not 4HI Loc, you still only have 1 wheel drive unless you have lockers or limited slip diffs. It'll work just like your rear differential will work without a locker. It will power the axle that has the least traction, just like a rear end will power the wheel with the least traction and that's how you get stuck. So as long as your wheels have traction it should just power 1 axle at a time, could be the front, could be the rear. This is why if you take the front driveshaft out, the truck won't move because its going to be easier to spin the front take off of the transfer case and that is what will spin. So you have to have both shafts in, or use 4Hi Loc, and keep both front wheels locked in. Point I'm making, the FULL time 4x4 is not as bad as having one of the other model transfer cases in 4HI all the time. Then when you'd use 4Hi Loc, then its like the other transfer cases in 4HI and it will run both axles and not differentiate the axles. The Part time has been known to have lubrication issues with this Tcase. So you must put it in 4Hi and drive it every so often to make sure it stays lubed. If it were me, I'd just leave it alone if I wasn't going to swap to another Tcase. As long as your in 4HI, I don't think it would be all that bad, and not worth the risk of tearing up your Tcase. And if you're that worried about it, I think the money towards a different Model Tcase would be better spent than doing the Part Time kit. But that's just the way I understand it to be, and that is my opinion. Hopefully another wheeler like C4 who knows better can deny or confirm for us.

if the 203 is a true open differential just like the front and rear axles are then all 4 wheels will get power. but when you lose grip itll spin the axel with the tire that has the least grip. when nothing is spinning it gives equal torque to both axels. actually it ALWAYS gives equal torque thats how an open diff works. the common misconception is that a locked diff sends equal torque and and an open sends all power to the wheel with less grip. this isnt true. a locked diff spins the wheels at equal speeds regardles of the condition so it is possible for one wheel to recieve all torque. in an open diff all wheels recieve the exact same torque and if one slips all wheels are pulling just as hard as the wheel without grip. which is next to no power. i am surprised so many people dont get that. in an open differential one side relies on the other as far as torque goes so if one wheel has no grip the other cant do work. i know im no expert on these or any cars or trucks but i do have a very good mechanical understanding of a differential