NP 203 Chain Replacement

I have a Jeep CJ with a Chevy conversion... 350 to 350T to NP203.  It's been giving me a lot of clanking noise when I lock the hubs and I have (I think) discovered the problem to be slop in the front drive shaft due to a very loose chain in the NP203.

My question is this:  I have read that replacing the chain is a real chore and there is high risk of losing loose bearings, etc if you don't know exactly what you are doing (I don't).

Given that a new chain is about $164 and I can get a rebuilt transfer case for about $250, what should I do?

I'd like to replace the chain myself but if it's really that hard and I don't want to risk messing it up worse.  Any thoughts?

Also, where can I get some decent instructions on how to make a chain replacement?

Thanks all.  

If you run around with the front hubs unlocked and the NP203 in Hi-Loc, then you have damaged the NP203. In order to run with the hubs unlocked, you have to convert the NP203 fulltime function to a part time capability. There are kits to do this.

If you got another NP203 and ran the hubs unlocked, it would do the same thing in short order. The NP203 is designed to work with hubs that are always locked.

Since the NP203 has a center differential, the only way that you'd be able to drive the Jeep with the front hubs unlocked is to lock the NP203 center diff (Hi-Loc or Lo-Loc). Otherwise your front driveline would just spin and no power would go to the rear driveline. This causes the internal coupler on the differential to develop a lot of slop, eventually causing a banging noise and then destruction.

So, you should be considering a NP205 part time t-case and forget about the NP203 all together.  

Thanks for the info.  A couple of questions:

First, it is twin-sticked... I run it in 2WD High with the hubs unlocked.  With a locker in the rear, I rarely use 4WD.  I know that the front drive shaft does not spin when in 2WD High (or low).  Would this also damage the NP203 or did the previous owner already convert it to PT?

How sure are you that the coupler is toast?  From what you say, the new chain won't cure my problem.

I would like to convert to a PT 205 but I just dumped $600 into Tom Woods custom drive shafts and the 205 case would probably cause me to have to replace them again :-(

Thanks in advance.  

Does one of your sticks shift Hi-N-LO and the other shifts 2WD-4WD? Can you run in either position on the second stick (2wd or 4wd) without the front hubs locked?

If the answer is yes to both questions, then it sounds like it's been converted. The next question is how was it converted. There are two ways to convert the NP203, replace the spider gears in the original differential case with locking tabs or install a new main shaft that completely rids the t-case of the problematic differential.

Option 1 works fine for small tires and seldom used 4WD. That is, a grocery getter that is looking for better fuel economy.

The weakest and sloppiest part of the NP203 is the differential. It is responsible for all the wear and slop that gives the NP203 such a bad name. Lockers and big tires will also destroy the locking tabs if that's the way it was converted. When the tabs begin to wear, then you feel a bunch of slop just in 2WD.

MileMarker sells both types of conversion kits. The new shaft/differential replacement is the only way to go if you plan on keeping your NP203.

If you are not hearing clunking while driving around in 2WD and you only get clunking when in 4WD, maybe it is your chain. Often times there are multiple areas of wear that cause slop in the NP203. Add all the slop together and you get the NP203 woes.

Click Here for some reading about the why's and how's for the NP203 woes.  

Affirmative on the twin stick set-up... I can run in 2L, 2H, 4L and 4H all without locking the hubs.

No banging in 2WD so I am going to go with the chain as my culprit for now :-)

Also, taking it to my shop... after all this, I am not at all comfortable trying this repair myself -- even though I hate to admit it.

Thanks for the help.