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Th400 np205 input bearing diameter?

Discussion in 'OffRoad Design' started by mudddog91, Apr 29, 2003.

  1. mudddog91

    mudddog91 1/2 ton status

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    Hey was wonderimg if you could give the the outside diameter of the 32 spline np205 input bearing so I can get my t-case bored and order a bearing and input shaft kit from you?Is this bearing also held in by the adapter with a lockring keeping it from faling in too deep?Do I have to worry about having anything else done to the case besides a straight bore of the correct diameter?Thanks for the help
     
  2. 77fixer

    77fixer 1/2 ton status

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    Read "Converting Input Shafts in 205" on this page.

    Brett
     
  3. mudddog91

    mudddog91 1/2 ton status

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    OK the site says about 3 1/2 "Arent all 205's machined to the same spec for a th400?Or is the site telling me to bore it to 3.5" and it will be good?I understand that it would be better to have the bearing in hand but Im sure GM didnt custom fit each bearing to each t-case so I was asking for the bore diameter so I could have the case at the machine shop in advance.I dont have a bearing and an input shaft yet and i am planning on buying it from ORD so whats the big deal?Is it a secret?
     
  4. BadDog

    BadDog SOL Staff Member Super Moderator Author

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    Believe me, Stephen knows what he's doing when he says take the bearing. I took the original bearing and the new bearing. Gave both to the guy, told him I want the new bearing to fit just like the old bearing. He over bored by at least 0.003 and now the bearing just falls out if you tip the case over. /forums/images/graemlins/frown.gif What the shop should do is mill it out conservatively, the actually *CHECK THE FIT*. Not as easy as it sounds because the case gets hot, distorts, and makes it hard to hit the dimension exactly. You also don't know what your getting for a machinist (as I found out). If you get Bill (A-Tron) or one of the guys at ORD, people who are accomplished machinist, or at least do this particular job regularly, your probably safe to bet that they can get it right. Still, even they will want a bearing to test fit...

    <Edit> If you really bound and determined to ignore the warning, look up the specs on the bearing, there are sources on line and local for you to do just that. If you do, good luck. But Stephen has already said that he is not comfortable posting the size since that would make him feel somewhat responsible.
     
  5. mudddog91

    mudddog91 1/2 ton status

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    I understand the warning and the reasons for sure.SO are you running that t-case thats been overbored by .003"?
    Also since the new bearing is about 3.5 inches then is the output shaft bearing for the 203 range box the same as the th400/np205 input bearing?Maybe same part number??Just an Idea.............the 203 bearing measures 3.453"
     
  6. BadDog

    BadDog SOL Staff Member Super Moderator Author

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    I don't know about the 203 bearing, no help there...

    I am running the over-bored case. I would have pushed the issue if I had needed it for a daily driver, but this is a trail rig. Now, I should also say that the stated magnitude of the problem varied depending on who I talked to. Some said, "hell no, make them fix it, it won't work!", but they were a distinct minority. The machinist at 4 wheeler supply who did the work has a fairly good rep among people who live around here, and he *swears" that this is the way he does all of them, and they have done quite a few. Talking to Stephen and James at ORD (who certainly know their stuff on this count) it is only a moderate problem. James said that he had seen the bearing on some unmolested factory cases that just slipped right out like mine. However, he said there is no way he would accept that on a case he did.

    What I wound up doing was slightly peening the bore just a little with the corner of a small, slightly blunted cold chisel in 6 locations spaced around the bore. This is a touchy situation with cast steel case (James warned me of this) due to it's tendency to fracture, rather than displace like steel, so I was careful and very "gentle". Anyway, this produced a slight resistance to the bearing insertion. Next, I cleaned it with break cleaner and used Loctite Sleeve Bonding liquid (made for piston sleeves, high temp, his resistance to sheer, and oil resistant; supposed to handle up to 0.005 clearance fit IIRC) to retain the bearing. Moderate prizing with a small pry bar does not move it...
     
  7. mudddog91

    mudddog91 1/2 ton status

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  8. Stephen

    Stephen 1/2 ton status Moderator Vendor

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    The 400/205 input bearing is the same as the NP203 input bearing, and also the bearing in the alum. domed bearing retainer in the back of the 203 gearbox.
    You're on the right track with looking it up, etc. You should be safe boring it for the 203 input bearing. Bearings don't vary in size much, I'm sure there's a tolerance for the the different bearings but practically it's measured in tenths of a thousanth so you can bore it to fit one and it'll fit another of the same number.
     

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