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NP205 assembly/differences based on year? Yes!

Discussion in 'The Garage' started by dyeager535, Nov 28, 2006.

  1. dyeager535

    dyeager535 1 ton status Premium Member

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    First off, yes, I need to go get the "real" GM manual for an '85+ truck. This '86 "pre" manual doesn't cover t-cases. Anyways....

    So I've got a wobbly rear output on my '91 205. With the engine running, truck sitting, the output moves about 1/8" up and down. Input shaft was bent, replaced that with a supposed good one (never actually checked runout, but came from a runner) but once installed, noticed this problem.

    Just tore down a 10 spline 205 for the output shaft, (trading it for another) and realized there is a difference where the input shaft "stub" rides in the rear output assembly. On the 10 spline (older) output shaft, the roller bearings are "captured" in the assembly with a flat washer and a snap ring. On the '91 205, upon disassembly, I see that the bearings are NOT retained, but appear to have the groove for the snap ring. There is a washer, but it was installed underneath the roller bearings.

    Parts in question are 23, 24, and 25
    [​IMG]

    If you can't view that, or want larger, it's one of the links here:
    http://dyeager535.topcities.com/partsmanual.html

    According to that pic, it SHOULD be setup just like the older case I have. Or, GM machined the input and/or output shaft differently to do away with those pieces?

    Anyone comment as to the retention of those roller bearings that has more experience with multiple years of these cases??
     
    Last edited: Dec 5, 2006
  2. IIVIIoonshiner

    IIVIIoonshiner Registered Member

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    i just finished with an older style 10 spline and my diagram was identical looking for those particular pieces.... I put in the long roller bearings then a washer and then snap ring and slipped it on over the other shaft.... I would go with that. now if yours came apart differently than in that diagram and/or does not seem to work that way then you need to find a mechanic buddy that subscribes to directional software... they pay 300 bucks a month to have all the updates and step by step inst. on how to do it. (It helps to be friends with mechanics so that you can use this for free)
     
  3. nvrenuf

    nvrenuf NONE shall pass! Premium Member

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    I have a 91 GM book at home, I'll compare pics tonight and tell you what I find.
     
  4. dyeager535

    dyeager535 1 ton status Premium Member

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    I appreciate it. I hope this is the problem, but I somehow suspect it's not. Not sure why someone would get into a 205 in the first place, let alone leave pieces out. :)
     
  5. MEK5

    MEK5 1/2 ton status

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    There should be no difference between the early and late 205s,looks like it was assembled wrong.I dont think it has anything to do with the wobble your getting,could your rear output be bent?
    How about alittle history on the bent input,how did that happen?
     
  6. dyeager535

    dyeager535 1 ton status Premium Member

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    Ther rear COULD be bent, but it's not visible just by looking at it, while the front was.

    Got the case out of an insurance total V30. (stolen and driven VERY hard) Truck was apparently jumped, as the t-case adapter broke in half at the same time the 4L80E output shaft broke off, which bent the input.

    The problem I had with the rear output being bent theory (my original thought) is that the "weak" section of the input/output coupling is on the input shaft. The roller bearings show no wear or problems at all. The rear output bearing did break a bit off of the nylon used to retain the balls in place, which was more than likely from the impact I suppose, but the bearing doesn't have much play in it at all.

    Since the output shaft isn't even turning when I can see it move, other than another bent input stub, I can't see where the problem could be to be honest. I've had the case bearing retainers off/out, didn't notice anything really out of the ordinary...
     
  7. IIVIIoonshiner

    IIVIIoonshiner Registered Member

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    when i rebuilt mine it wobbled on the rear output but all it needed was a new bearing and the bolt was loose that held the yoke to the output shaft...
     
  8. nvrenuf

    nvrenuf NONE shall pass! Premium Member

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    Fwiw, I just compared my 91 book to your diagram and they are identical. :wink1:
     
  9. MEK5

    MEK5 1/2 ton status

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    I would just swap out that output and bearing and see if that makes a difference.Sounds like that thing took a hard hit to do all that damage!
     
  10. dyeager535

    dyeager535 1 ton status Premium Member

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    Thanks a bunch for looking that up. Appears someone was in there and took some pieces out.

    I'm hopefully doing the output and bearing here soon, if that doesn't fix it, I guess I'll be trying the small bearing 205 case w/32 spline input swap. :)
     
  11. dyeager535

    dyeager535 1 ton status Premium Member

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    Well, took the other 1991 apart (thanks Allan!:)) and sure enough, it was assembled with a snap ring and washer on top of the rollers.

    Also, for some "tech" on the 205, the rear output shafts are NOT all the same. I was told they were, however the one I have on my garage floor (SN ends in "72", meaning 1972?) was not splined to take a speedometer gear. It's an interference fit based on the yoke being tightened against the speedometer drive gear.

    Below is a picture of the 1991 VSS output shaft and the reluctor ring, where you can clearly see the splined section of the output shaft designed for the reluctor ring.

    Now, does anyone know if ALL previous 205's used the same speedometer gear setup, or did they start splining the shafts before 1991?

    [​IMG]
     
  12. MEK5

    MEK5 1/2 ton status

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    Oh Boy, You did say that you had an older 205 :laugh:
    The REAL early 205s had that non splined speedo journal up to somewhere around 74-75 I believe. I have found that type on the GM and Dodge but not the Ford 205:confused: they had the splined shaft.
    Also you will notice that the speedo connector was at the bottom corner instead of the top.
    The shafts were the same as far as your washer, snapring order goes.You wont be able to use the old shaft though!
    The splined speedo journal is not a 91 elec speedo thing,any replacement shaft will have the splines well except that old stuff.

    Rereading the thread you said you could see it move up and down with the engine running and then later said without it moving:confused:

    If you can wiggle the yoke up and down by hand then I would say replace the bearings, rear output and the caged needle bearings in the output housing.

    Remove the output housing but leave everything together including the yoke and clamp it in a vise to see whats going on.

    Heres a picture of the old style and a new 205 shaft

    IMG00001.jpg
     
  13. dyeager535

    dyeager535 1 ton status Premium Member

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    Yes, it's a bizarre condition is all I can say. Without the truck moving, driveshaft stationary because the wheels are on the ground, transmission in neutral, the rear output shaft moves up and down. I could not stop it from moving like this even with most of my body weight hanging from the yoke. I cna't recall, but *believe* it only wobbles like that with the case in gear. (it's only been a year since I've had a chance to play with it!)

    I didn't detect much if any play by hand from the previous assembly, but I've replaced the ENTIRE output shaft assembly to include the output shaft housing/bearing retainer sections, so there are no rear output or input pieces left from the original case from the beat up truck except the input shaft bearing, which I didn't have at the time. Now I do, so if it still wobbles, guess I have one more option to try. Since I know the problem though, turning the input shaft by hand with an indicator on the rear yoke would show the problem with it out of the truck. Just trying to save tearing it out of the vehicle. :(
     

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