More on ? np203 and part time kit

[1976er]

So, again 76 Chev 3/4 ton full time 4X4.  I have the np203 and full time hubs.  From what I have read here a stock 203 will not move the truck if the front drive shaft is removed and transfer case is in Hi (not lock).  Apparently my 203 has a part time kit as the front drive shaft is removed and the truck will move in Hi.  I quess my question is being that I have full time hubs is it possible for any damage to be done "IF" indeed there is a part time kit installed in the 203??  As some may have noticed my earlier post as to trouble with 203 jumping out of HiLock.  Then again, why would someone install a part time kit and leave the hubs alone?  Anyone???

[zieg85]

I would venture a guess to your question...  Since the truck is 35+ years old the original transfer case may have been replaced with a junk yard one that already had the kit in it and did not know about it???

[Jason S]

I would venture a guess to your question...  Since the truck is 35+ years old the original transfer case may have been replaced with a junk yard one that already had the kit in it and did not know about it???

Ditto

From what I have read here a stock 203 will not move the truck if the front drive shaft is removed and transfer case is in Hi (not lock).  Apparently my 203 has a part time kit as the front drive shaft is removed and the truck will move in Hi.  I quess my question is being that I have full time hubs is it possible for any damage to be done "IF" indeed there is a part time kit installed in the 203?? 

If your NP203 did not have a part-time conversion, is set in the Hi position (not Hi-Loc) and you removed the front driveshaft, the truck would not move.

In stock form, the NP203 transfer case Hi or Lo positions work like an open rear end. All the power is transmitted along the path of least resistance. If one of the driveshafts is removed, there is no resistance due to the missing driveshaft and so power will go in that direction.  Installing a part time kit locks the transfer case differential (like a spool) and forces the power to go to the rear driveshaft when the case is in the Hi position.


With the drive gear installed in the front hub, the front axle shafts and front drive shaft would be turning any time you're driving down the road.  It would be the exact same action as if you had a pair of manual locking hubs installed and in the lock position.  There isn't really any issue with the front turning and having a part time kit in your NP203.  You'd have unnecessary wear occurring on the front axle shaft u-joints, differential and front drive shaft u-joints, but it isn't really hurting anything.

If indeed your NP203 has a part-time kit installed, you should drive the truck in 4-wheel drive every so often to keep things lubricated.  Since you have the factory drive gears still, you'd just need to put the t-case in Hi-Loc or Lo-Loc and drive it around on a dirt road or off-road for at least a mile or so. 

If you confirm you have a part-time t-case, go ahead and throw on a pair of locking hubs to save some wear & tear and fuel.

[1976er]

Manual hubs does sound like the way to go if it does have the part time kit, once I figure out the problem with the 203.  I never been into a Tcase, what does a part time kit look like, is it an obvious observation?  Also, I did have to swap out the front differential, the ring and pinion gears were missing teeth and ring gear was loose on the carrier.  Which reminds me, the hubs that were on it had six bolts holding the cover over the end of the axle; the differential I picked up has "tap on" caps; came from a 1973, under the caps look different too; is that an issue?  Yes, it is the ratio needed 4:09, rear is 4:10.  Appreciate all the help I can get from you all.  Thanks

[bake74]

     If you buy manual hubs to put on (which I agree with Jason S, you should if you have a part time kit), the ends of your axles are going to be replaced with the hubs, so it will not matter (if memory serves me right the parts come in the hub kits).  They will bolt up to the housing with the parts in the kit.
   

     So here is an image of the milemarker kit.  The most noticeable difference is the 4 wedge looking parts with the holes in the middle.  Hope this helps and keep us informed on what you find when you break the case open, pics are always welcomed.

[1976er]

Yes, that will help to identify a kit.  Thanks

[Jason S]

From your description:

The front axle with the tap on cap is sounds like a 77-79 axle (assuming it's a 3/4 ton axle with 8 lugs for the wheels). The manual hubs for that axle would be the same as the 1/2 ton hubs for a 73-87 (internal locking hubs).

The axle you removed which had a 6 lug cap uses external locking hubs which were found predominately on 70-early 77 Chevrolet/GMC 3/4 ton trucks and 67-early 77 Ford F-250's.

If you could post a photo of what you have, it'd be much easier to verify.

 

[1976er]

Let me see if I can get some photos up.  The "tap on", probably more like dust covers, came from a 73 out of a parts yard; so very well could have been replaced at some time on the 73 as well.  Probably take me a couple days to get pics up.  Funny thing, the axle housing (differential) on the "73" is about a 1/4th inch larger than the current axle housing.  I had to go back and get the top plate and u-bolts as to fit, mine were too small.  Thanks

[Engineer]

When I bought my '77 in early 1988, the previous owner had installed a prt time kit in the NP203, but left the full time hubs in place.

I put a set of Warn lock outs on it. Then all was GTG.

But after swapping the 203 for a 205........ Life is good.