NP208 Trashed Thrust bearing!

[schwenk industries]

I won't go into great detail about the story I will save that for the NV4500/M1009 Swap thread. If there is interest? (I did not want to fill that up with this question/Info) So after removing my NP208 for my trans swap. I pulled it apart to inspect bearings, gears and replace the seals and gaskets. There was some sort of disintegrated bearing stuck to the magnet near the drain. At first I had no idea where the bearing came from, After checking over the parts diagram in the TM it turned out to be the main shaft thrust bearing. All other components and bearings where closely inspected for damage, A couple others will need to be replaced no big deal.

This Thrust bearing was not available threw most transmission parts companys I found online including GM. The TM listed GM part numbers: 09424093 and NTA-2435. Turns out the second happens to be a Koyo part number available at Motion Industries for $3.78. The specs for NTA-2435 OD: 2.187 ID: 1.500 Thickness: 0.78 seem to be a fit. How ever both the bearing surfaces on My main shaft and Input shaft are galled. Motion sells a Washer for the NTA-2435, TRA-2435 with a thickness of .030.

Here comes the question should I Face .030 off both bearing surfaces to give a clean true surface and run a washer on both sides or just polish up the surfaces and throw a new bearing in? The only time that thrust washer will turn is if the T-case is shifted into low. Also any ideas on what might cause that bearing failure? When I Picked up the truck the ATF was very Low so probably starved for oil, only force against that bearing would be the rear sliding yoke moving inward. Sorry for the long Post any info, Questions, Ideas, are greatly appreciated.

 

[cucvrus]

Very nice work area. I like how clean it is. I get a clean area like that about once in a 5 year span. Then I just go wild and tear into something else to cover up the empty space. I have been moving the projects right in and out so far this year. I have lots of spare bolts and parts. Every time I take something apart I feel compelled to take another of the same thing apart that is junk so I can use the best parts of both pieces and discard the bad ones. But I must say I do like your work bench. Mine is covered in spare parts that I just can not discard for the life of me. Parts are parts and good parts are hard to come by. If they are bad they go out. I sort my parts in big tubs and keep them with the same type most of the time. It is to hot to sort so they are piling up now in the barn. I just sold an SM465 trans and transfer case that I had laying around for 20+ years. I will never miss it but did not want to give it away.

 

[schwenk industries]

The bench is stacked high to the left with other parts, I keep that 1/4 of the bench clean for projects. Being a Machinist and also a mechanic I have a little bit of the Keep things clean and orderly, I wish I never had piles of parts but I just don't have enough room to keep everything as organized as I'd like. All my bolts small parts are organized by size in small parts bins and drawers below the bench. I know how the tearing into multiple things at once goes its a bad habit for me.

 

[CUCVLOVER]

If the shaft has a bearing surface down you should be able to weld it up and re turn it to the correct measurements.
My dad owns a welding and machine shop so that is something we do all the time.

 

[schwenk industries]

yep when a bearing spun on a shaft stack up a couple TIG beads and turn it back down, we didn't have any spray welding equipment unfortunately. I just don't want to affect any heat treatment that may have been done to the gear or splines, come to think of it I never checked if any of those surfaces are hardened. May have to be ground?

 

[CUCVLOVER]

Its possible it could be to hard to turn down but I guess you could just weld it up turn it down then have rehardened.

 

[rustystud]

That is rare for a Torrington to get destroyed like that. What oil are you using in that transfer-case ? It should be ATF.

 

[Chaski]

Another idea to toss out there is to get another 32 spline np208 to harvest parts from. If you search your local craigslist there was one NP 208 for $75 and another for $80.00. Only catch is to make sure you get a 32 spline one instead of the 27 spline version that was behind the TH350 & 700R4. Only difference is the input, but since yours is roached that is important.

 

[schwenk industries]

ATF only Per TM / GM I Figured It was strange as well that's why I posted it. I Might pick up a parts unit I will have a parts TH400 maybe someone Will trade.. I can hope anyways.

 

[cucvrus]

I have several NP208 parts transfer cases. 3-4 + in the shed. What do you need?

 

[Foxtrot Oscar]

I won't go into great detail... ... Sorry for the long Post any info, Questions, Ideas, are greatly appreciated.

Don't apologise. The opportunity to see inside a T-case is rare for me. To see a problem and its solution even more interesting.

The bench is nearly as fascinating as your bearing issue. I like the look of it too (wooden top!) and could see your pile of parts at the LH end. As has been said, it's great to have a clean surface to spread your project out on and be able to work in sequence rather than digging parts out of a box of jumble.

I concur with Rustystud who notes, it is rare for those thrust bearings to fail - but it's not unheard of. It is possible the truck may have experienced severe Low Ratio work during its Army life (or after) and/or sometimes sh*t just happens.

Back to the bench... It looks to be commercially made? There is an interesting plaque on the drawer just under the vice on the RH end. Can you post a pic please?