well, I pulled the transfer case this evening, and sure enough, coupler was stripped on one end:



here's what it should look like...



Looks like they are $95 or so, plus a gasket. I need to tighten up the output yoke for the front axle side of the transfer case, but the oil had no shavings or metal in it. Is it correct that the front of the transfer case housing would have gear oil in it from the transfer case? Should this coupler be greased when installing? Doesn't look like it was before.

Thanks for the advice, looks like andyr354 called it exactly.

 

If that coupler isn't in oil then I would liberally coat it with never-seize or get some spline lube from your PTO distributor. Chelsa had a good lube, however I usually just use never-seize as it keeps the splines from galling and give it just enough lube.

 

I had forgotten that the coupler was in mine.... but what i remember from other conversions is that the tail housing of the Nv4500 should have the synthetic tranny oil in it. Thats where the overdrive is.

Other Nv4500 setups have a female input on the T-case, and have the tcase sealed from the input. No coupler.

From memory... does the seal press into the aluminum tail housing of the NV4500???

and, did the cast iron coupler housing of the NP205 have gear oil in it when you seperated them?

If so,
I think the oil in the coupler housing area would have come from the tranny... Did you check the tranny fluid level yet?

One thing i remember from this and other conversions, is that you fill the tranny when dry, then during the first few miles, some fluid would cycle its way into the coupler cavity leaving the tranny low on fluid... When i did NV 4500 conversions on jeeps and cruisers back in the mid 90s we would have to top them off after the first few miles. This is pretty specific to the transfer case you use behind them though....and especially true if you are using an advance adapters tail housing too.


As a habit i have always overfilled all my gearboxes.
I have some tranny shop buddies that have told me that drain plugs are only in the locations they are to save $$ at the factory, and that its a good thing to over fill cases to a certain extent. My Nv 4500 has the aluminum capacity increasing coolers installed on the PTO covers, and i have an extra gallon of the synthetic oil in mine. (2quarts above the fill plug). This might be one way to get extra fluid to the coupler. dont over fill too much or it may over heat and blow out the seals. Extra oil keeps you cooler, and keeps more oil at the bearings, might increase drag though.

 

Wow, I remember when I was pulling mine thinking "this is all that holds the power from the almighty cummins from the trans to T case?"

I didn't put anything on mine when I installed it, but I think when running gear oil or trans fluid should splash onto it. I have 1k miles or so since I did this, and not problems yet. I'm putting a decent amount of power through it, too.

 

Its normal for oil to be in that housing, but it should come from the trans and not the transfer case. If its coming from the transfer case its going to need a new input seal.

You shouldn't have to grease the coupler, just make sure you put it in, I almost forgot one time. Good thing my helper noticed.

 

When I ask about the oil in the housing, I'm not talking about the aluminum transmission extension housing that bolts to the crossmember. I didn't pull that part. I'm talking about in the front of the transfer case itself, and the oil that is in there is definitely transfer case oil because it matches the slightly milky looking oil that came out of the transfer case. Everytime I change the transfer case fluid it seems kind of wet. But i did have to drive through some deep-ish floodwaters earlier this month, so it's not too surprising, I guess.

No, the coupler wasn't pressed in, I pulled it out of the extension housing by hand. the transmission side was pretty dry looking though, so I will double check my tranny fluid and probably put a little lube on this thing when I put it back. the transfer case end of the coupler where there was some oil loose in the front of the housing, was fine.

"Wow, I remember when I was pulling mine thinking "this is all that holds the power from the almighty cummins from the trans to T case?""

yeah, that's what I thought too...