Need HELP!! np203

[Jaysonb]

My truck has a np203 that has been converted with a part time kit before I got the truck. The 4 wheel drive has worked fine for the last year, but yesterday i locked it in, and only had 2 wheel drive, and I could hear a noise like something was only partially engaged. The front axle would engage sometimes. I put it on the lift today, and the linkage is adjusted fine, and my shifter is clean, and works fine. Are the bearings in the part time kit that take place of the spider gears prone to fail? And if they did would these be the symptoms? The main chain must be ok, the front axle did engage intermittently. With the truck on the lift, and the linkage from the shifter removed, I would lock it in 4 and the front and rear drive shafts would move together like they should, but take it off the lift and not change anything, and only rear wheel drive. Any help is appreciated.

[motornut]

I did have some sticking before,but sprayed lots of lube under it,seemed to help.
try working threw the gears,
somewhere it can slip,and make sure your front hubs are locked in(on all the way).

[enaberif]

The issue with the NP203 part time kit is that if you don't mod the case to allow overfilling of the transfer case you need to ensure you always run the transfer case engaged to properly lubricate the internals.

Without doing this yes you can do internal damage to the transfer case and damage it.

[Jaysonb]

Originally Posted by motornut

I did have some sticking before,but sprayed lots of lube under it,seemed to help.
try working threw the gears,
somewhere it can slip,and make sure your front hubs are locked in(on all the way).

I unhooked the shifter all together to rule that out, had the transfer case shift arms in the lock 4wd position, under the truck on the lift both drive shafts seemed to be locked in, but under power i only had rear wheel drive. I tested the front hubs while on the lift as well, they seemed to snap locked fine while spinning the wheel and turning the dial to lock. Maybe I should put my slugs back in to rule out the hubs.

[Jaysonb]

Originally Posted by enaberif

The issue with the NP203 part time kit is that if you don't mod the case to allow overfilling of the transfer case you need to ensure you always run the transfer case engaged to properly lubricate the internals.

Without doing this yes you can do internal damage to the transfer case and damage it.

I would lock everything in 4 wheel and drive a few miles of gravel every 200 miles or so, but who knows if the guy before me did. I just need to figure out what might have got damaged. I cant find a 203 around here, I can get a parts truck with a 205 in it, but I just spent about $300 on a new front drive shaft a few weeks ago, so I'd like to try and fix this one.

[motornut]

I'd put the slugs back in for a try.

[ray_mcavoy]

Here is some good info on the 203 case and part time conversion --> http://coloradok5.com/milemarkerpt.shtml

Partway down on that page they describe how the front output is engaged:

The way the NP203 performs "LOC" or Locking to drive both axles with equal power was with a sliding collar on the top chain gear. The collar would slide over the crown gear and engage teeth on the differential case. This locked the top chain gear to the differential and would not allow the gears to spin giving a 50/50 power split. Once the transfer case is converted then the sliding collar becomes the only drive to the front drive shaft.

And the pic from that site that goes with the quote:



So it's possible that the teeth on that lockout clutch mechanism are worn/damaged to the point where they are no longer holding under power.

[Jaysonb]

I wonder what engages the sliding coller , that's what it sounds like, somthig with teeth just barely touching. Thanks for the replies so far.

[ray_mcavoy]

There are a couple of shift forks inside ... one that selects between high & low range ... and another that moves that sliding collar. Google "NP203 exploded view" and it should bring up a bunch of diagrams that show the fork & internal linkage that connects it to the shaft where the external linkage attaches.

[craig113]

You mentioned that you had to manually lock your front hubs. I had a buddy that his did not work one time. He had a shop replace the front calipers and lube the front bearings. Upon my inspection I noticed the clutch cup was installed backwards and one hub would not engage. Thus with the limited slip the front would not work until both sides lock up.

[Ziegelsteinfaust]

If you were close I have 2 203's in my garage for parts right now.

Also check the locking hubs like a guy above said.

Mine got locked in lock, and I never could get them to unlock. So I tweaked them so they won't lock. Till I get the proper gears for the front, and I have new hubs anyways.

[Jaysonb]

Originally Posted by ray_mcavoy

Here is some good info on the 203 case and part time conversion --> http://coloradok5.com/milemarkerpt.shtml

Partway down on that page they describe how the front output is engaged:


And the pic from that site that goes with the quote:



So it's possible that the teeth on that lockout clutch mechanism are worn/damaged to the point where they are no longer holding under power.

That is exactly what it is. The teeth on diff carrier are totally gone!! I found one on eBay for $25, I might just put it back to full time, looks like I have an old warn part time kit in here.