NP 205 transfer case leak

[Jcfcamaro]

Thought I'd post this to help anyone with a np205 transfer case leak at the speedo drive. Reading different post the factory used a oring on the pinion shaft but is pretty prone to wearing out and leaking so GM started selling new adapter nuts with a larger I.D from .506 to .579 to have a press in seal to help hold back the oil, but now are discontinued by GM # 326561. Other places are making the same adapter nut with the new style seal but the I.D of the seal was larger than my .250 shaft size. Ended up going to napa auto parts and looking through there seal book and found a seal that would fit my .250 shaft and also the .506 O.D part number 2450 SKF brand. The seal fits perfectly on the shaft I.D but just barely catches the inside of the nut where it presses into( nut Is .506 and the O.D of seal is .505) but with some bearing epoxy or a punch with some light Mark's made inside the nut it will hold fine. Just thought I'd make this post to help anyone with the same issue. P.S the new style nut is around 50.00 vs this seal I bought was 5.99.

[Jcfcamaro]

Here's me with a punch and making some light dimples to hold the seal once I press it in. I will also use a lite film of RTV silicone around the outside of seal to make sure it seals .

[v30crewcab]

thats good info. thanks.

[57taskforce]

Thanks for the info! I’m sure I’ll be crossing this bridge in the next few months as my K20 nears being road ready. Thanks for taking the time to not only figure this out but for sharing it as well.

[Jcfcamaro]

I will say when I put everything together I installed the gear shat into the nut/seal first then put it in the speedo housing. Putting the gear in first then trying to screw the nut in and aligning the shaft with the seal was a little hard and I was afraid of damaging the seal so that's why I put the gear into the seal first and used a small pick to help walk the seal around the shaft. Once it was together I used a small screw driver inside the square hole where the speedo cable goes in to help steady it while I screwed it in and tried to catch the other bushing inside the housing that the other end of the gear goes into. Hope this makes sense and you might be fine installing the gear first then screwing the nut on. This is just what seemed to work better for me.

[El Dorado Jim]

thanks for the info

[jjzepplin]

Thank You for this info. Do you have an update as to whether this solved the leak long term?

[Jcfcamaro]

Originally Posted by jjzepplin

Thank You for this info. Do you have an update as to whether this solved the leak long term?

No update as I'm still building my truck, but I can't imagine it not working.

[jjzepplin]

I was thinking I could possible "flare" out the lip of the seal so it would fit better. It's cheap enough so I will try it.

[Jcfcamaro]

Originally Posted by jjzepplin

I was thinking I could possible "flare" out the lip of the seal so it would fit better. It's cheap enough so I will try it.

Great idea. I'd use a little RTV also.