Hi all,
The NP-208 in my '81 is starting to make some odd whining/whirring noises from time to time. The sound'll kick in at highway speeds and will continue until I come to a complete stop, and then won't come back until I get to high speeds again.

Also, when I shift-on-the-fly between 2HI and 4HI, it grinds for a few seconds and then clunks HARD into 4HI.

Other than that, it works perfectly.


Is there just something inside I need to address? Or should I just rebuild the whole thing?

If so, are there any recommended rebuild kits? Any recommended "extras" to do while I'm in there?

Thanks for the input.

 

The shifting collar or buttons are going bad. They have two types. One has little nylon buttons that wear out and fall away, the other(mine) is a metal collar with a nylon channel the shifting fork rides on. The fork pushes the planetary into high and 2wd, when this wears out, it won't push it anymore. You will only end up with only low range eventually. Best to fix it sooner than later, cant get far in low range, it goes too slow for driving on the highway. While you are in there, rebuild it with new seals (and bearings if you can afford it.)

 

I avoid shifting on the fly, inertia isn't a good friend of mechanical parts, so i prefer being parked while i engage 4HI. You might need to research a little in the net, but those NP cases are very stout, you probably won't need to do more than installing the kit (once you find one).

Read this first (the post or Darryl): Which rebuild kit is best for the NP208? - (Transfer Case) - 4x4 Forum | 4x4 Mecca

Here is one: Rebuilt NP208 Transfer Case Parts Illustration and parts list, you save moneys! - Drivetrain.com

 

Thanks for the info. I'll most likely just rebuild the whole transmission again.
Yeah, it's not one of those whines where it whines more and more the faster I go, it's one where it'll be quiet, quiet, quiet, then suddenly out of the blue, NNGNNNGNNNGNGNNGNNNNN. Kind of a whirring, whining sound. Then, it'll continue (pitch changing with speed) until I come to a complete stop, and then it'll kick off. Won't come back until I'm up at high speeds again. It's definitely internal. I had rattling problems with my shifter before with the external nylon inserts where the shifter pivots, and that was something completely different.
This sounds like a bearing or something inside sliding out of place and rubbing against something else.

I've never known there to be an issue with shifting on the fly. My user's manual says there's no problem with it up to speeds of 40mph. Useful for conditions with patches of snow and ice. Shift to 2wd for dry patches/pavement, and back to 4wd for snow and ice. I can't imagine coming to a complete stop every time. 4LO is another issue altogether though.

 

I can see why would you shift on the fly under those circumstances, i just don't find anything like that down here , good look with the rebuild, you should make a mean write-up with a lot of pics!.

 

No worries, I'll take pics every step of the way and do a nice write up. Hope I can get to it soon.

 

Hey Joe had my transfer case go out it only works in 4 low . Seen this post do you know of a good rebuild kit for np208 out of a 1986 f150

 

I got a seal kit from my local transmission shop. None of the bearings were bad in mine, just tear it down and check everything.