Dodge RamCharger Central banner

NP 203 confusion

5K views 34 replies 12 participants last post by  pat_t338 
#1 ·
I'm a little confused. I have a 1978 W150 4x4 that I traded for a while back, and I've been using it as my daily driver while I had some repairs done to another vehicle. It has the Lo Loc - Lo- N - Hi - Hi Loc gear shift for the transfer case, and I have just assumed that it is an NP 203. It also has manual lock out hubs on the front axle, with a D44 8 lug front and a D60 8 lug FF rear. I happened to look at the lockout hubs today and noticed that they were in the free position. First thought was OK I've been driving around in Hi Loc, so I checked the selector and sure enough it's in Hi Loc. I shifted into Hi and lo and behold, the truck still pulls, so I checked Lo and Lo Lock and it moves in both with the hubs disengaged. I was of the understanding that the vehicle wouldn't move with the hubs disengaged. Was I wrong? If not, what gives with my transfer case? Thanks.
 
#2 ·
It may have had a part time conversion done to it.
 
#3 ·
Thanks. I assume that means that it can be run in two wheel drive or four wheel drive. How do you switch between the two modes in that case, since the only selector is the factory five position gear shift? I'd guess that there should be some provision for switching from two wheel drive to four wheel drive and back, but it's not readily apparent in the cab. I climbed underneath, and while I'm no expert on transfer cases, it is a large cast iron, chain driven case bolted directly to the auto trans, and I was under the impression that the NP 203 was that type.

pat
 
#4 ·
The Truck will still move because the rear axle is driving it. By the sound of it Im going to also say it has had a conversion kit done to it. It is still a full time 4 wheel drive t-case so the front drive shaft is still turning the differential but unless u lock those front hubs the tires remain free rolling there is no power going to the front hubs. I'm sure thats how the conversion kit works. Unless someone decides to slap newer axles under that truck. You may want to look into how the full time to part time conversion kits work and see if thats your set up for sure. 
 
#6 ·
After doing some investigating of my own Im going to say you more than likely have the conversion kit done. Yes it does save only a little bit of gas because the front axle is still turning. I Have read tho that because the conversion in the hub uses the stock bearing on the spindle they take a lot of abuse on larger tires and bearings need to be replaced very often. I don't know what size tires your running but don't beat on it hard if your running larger than 31's or your wheels may be wobling of your hubs too soon. heh

But all in all your right there aren't too many advantages to doing this conversion kit. It probably take a little wear off your front tread life and just saved a little bit of gas.
 
#7 ·
Thanks. Big tires aren't a problem. It has 245-78x16's on it. I have an 84 with 33s and a four speed that goes off road for me. I only got this one because my daily driver quit on me and I needed something to drive around while I replaced the engine in the 84. I'm probably still confused on the whole NP203 conversion thing, but I don't see any need for it, given what you have told me. It seems to me that the conversion only replaces the lock position for high and low range, and eliminates the unlocked positions. I'll lock the front hubs and drive it like the factory intended. It doesn't make sense to spin all of those parts without putting the energy on the road.
 
#9 ·
If the t-case has been converted(and it sounds like it has) it will be 2wheel or 4wheel lock ( hi or low ). In 2wheel the front shaft is not powered.
 
#10 ·
The transfer case in his situation has not been switched or modified. He Most likely has the "Mile Marker" brand "Part time conversion kit" which simply puts a modified "locking hub" on the front hub making the wheels run free in the front. This allows them too then try to pawn it off as a gas saver. Keep it in all time the truck was meant for it. 
 
#11 ·
The mile marker part time kit does not only bolt selectable hubs to the front wheels but changes the innerts of the NP203 too.

The NP203 by nature has a differential in it to handle rpm differences of the front and rear axle during turns (otherwise the drivetrain would be loaded with torsional tension each turn your car makes and soon something goes booom). The mile marker kit makes it a part time tc by eliminating the differential and making the front output a selectable one (by connecting it to the all-time rear output).

In addition of the selectable front hubs this is by all means a part time 4WD now, but a one that should only be used on slippery or loose ground. Otherwise the torsional tension while turning may kill parts in the hubs or the tc.

Put it in 2WD, unlock the hubs and "save" some gas and drivetrain-parts  8)


Alex
 
#12 ·
ah see there is more to it than i thought. Awesome I didn't even know it altered anything in the transfer case. I was a little curious myself as to how all that would hold up spinning around in there with out the front hubs engaged. I knew a kid back in the day that would always forget to lock his hubs in 4 wheel lol
 
#14 ·
Under normal circumstances the NP203 is one of the strongest transfer cases that was available in a Dodge (the 205 ranks higher).  But that strength is cut in half by a Part Time conversion kit. A few of the members on here can give first hand info on that, ddgeramcharger79 is one of em. The 203 in his Ramcharger exploded (just the back half/aluminum tail) a few months ago  :eek:

Part Time converted 203's also have to be driven in 4WD frequently to keep the inside of the tcase lubricated
 
#15 ·
When I actually got to looking at it, it was in 4wd (Hi Loc) with the hubs unlocked. It sounds like this is probably the way I should be driving it on the road then, if I am reading all of you correctly. I read this article ( http://coloradok5.com/milemarkerpt.shtml ) and I gathered that it should be run in 4wd about every 200 miles or so at least for a few miles to lube the rear of the transfer case. This whole thing seems to me like a bad solution for a non-problem. I can't afford it right now, but it sounds like the best option is to remove the conversion parts and go back to the original setup.
 
#18 ·
I think he meant to swap in another NP203.
 
#20 ·
The way I understood it was that a stock NP203 was better than one with the part time conversion and swapping in another one was easier than trying to convert the part time on back to full time.
 
#22 ·
Rambunctious86, the OP suggested that he wanted to turn the transfer case back to the way it was suppose to be from the factory.  Which means tearing it apart and replacing parts that you would have to acquire from another transfer case.  So I said it would be just easier to swap in another working case.  I didn't read the link that was posted on this thread but others suggested that you have to put the part time 203 in 4 wheel drive every few hundred miles to lubricate the insides.  To me that doesn't sound like a good thing.  Therefore the part time 203 is less durable.
 
#23 ·
Maybe I'm over-thinking this thing, but I'm about to make a 2000 mile plus trip from Oregon to East Texas in this vehicle, and I'd prefer not to get stuck beside the road somewhere.

As I understand it, with the part-time conversion I need to put the xfer case in Hi-Loc (now 4 wd high) every couple of hundred miles to ensure the rear portion of the xfer case stays lubricated. However, I should not engage the front locking hubs because the transfer case differential has been replaced by the conversion kit thereby locking the front and rear axles solidly together.

Is there any advantage in locking the front hubs and leaving the transfer case in Hi (now 2 wd) to spin the chain and lubricate the transfer case?

I have two gas tanks on this truck and figure on driving between 400 and 500 miles between gas stops. The idea of stopping every couple of hours to switch into 4wd to lube the xfer case and then stopping to switch back just seems counter-productive to me.

I assume that since the conversion has eliminated the differential portion that shift on the fly is probably a no-no.
 
#25 ·
I gathered the shift change from the above posts. I also understand from some of the above that I need to run it in 4 hi with the front hubs unlocked every couple of hundred miles to lube the rear portion of the transfer case to keep from burning out bearings. I also gathered from some of the above posts that I can't run it in 4 hi with the hubs locked on the road, because now the front and rear diffs are essentially locked together with no differential action to prevent wind-up. So the question now is can I run it in 2 hi with the front hubs locked to spin the differential parts that need to be lubed, or do I just need to stop every couple hundred miles, switch to 4 hi (hubs unlocked) and run it for a few miles and then stop again and switch to 2 hi to keep driving.

I gather that I can no longer switch on the fly with the part-time conversion. On a long trip of more than 2000 miles it would be easy to forget to stop and do the 4 hi/2 hi thing as often as I think I'm being told. I suppose i could run it in 4 hi with the front hubs unlocked all the way to Texas.

It just seems to me that running the hubs locked in 2 hi would potentially be easier on the drive train than running it it 4 hi with the hubs unlocked. After I get settled and caught up in Texas, I'll get the 203 back to full-time 4wd the way it's supposed to be. Right now, I just need to get it to Texas.
 
#26 ·
Mile Marker made 2 part time kits for 203 equiped trucks. I have them both.

One is for the tcase. The loc  positions are locking the 4 wheel differential in the tcase. You can have low and high 2 wheel drive and low and high 4 wheel drive with this.

They also make locking hubs. I have this also. I lock the hubs before I lock the tcase in 4x4.

Either part time conversion will work without the other. Having both just eliminates the wear a little better.

Amd I think you can get these through Autozone if needed. STILL BE SURE TO KEEP THE FRONT BEARINGS GREASED.

I have not had a single problem with either setup except for folks have said they greased the bearings and they did not.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top