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will a doubler help me?

Discussion in 'OffRoad Design' started by great scott, Aug 9, 2003.

  1. great scott

    great scott 1/2 ton status

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    Of course the 4.1 low would be nice, but I dont fully understand what is used. I just scored a SM465/205 32 spline from an 86 1 ton chev with all the hydro parts and only 28,000 miles on the clock. I want the hydro and need the SM475 because I blew the rev gear in my 76 SM465. Problem is that the coupler on the hydro SM465/NP205 is gone and GM no longer has any. I have allways wanted a doubler and if I under stand the set up the gen II replaces the coupler. If it dose I am just one more step closer to a doubler. So is this the case, and either way what do I need and how much $$ to hook me up? My 203 is a 27 spline chev that I know nothing about it's origin.
     
  2. Stephen

    Stephen 1/2 ton status Moderator Vendor

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    You found good stuff. The nice thing about the later model 465/205 is that there is no drivesleeve between the two. You have a 32 spline input gear in the 205 and a 32 spline output in the 465. They couple directly. The adapter is a bit longer than what you had, by about 3 inches. This will help the front driveshaft angles if you're running in a single t-case configuration so I would call it a good thing in this case.

    To do the Doubler given what you have, you would need:
    1: a factory SM465 to NP208 adapter housing (? for a used one)
    2: a short 32 spline input gear in the NP205 ($140)
    3: a 32 spline input gear for your NP203 ($150)
    4: Doubler kit ($740)
    5: Shifter (you can build your own but we have them starting at $170)
    6: some labor to drill the front face of your 203 to the NP208 bolt pattern, plug some holes up,etc.

    You would use your 465 as is, no modifications, but you would have to change the input gear in the 205, which isn't really too big a deal. Pretty minor in the overall scheme of the mods.

    BTW, we can still get those drivesleeves (465/205 coupler), in fact, I think we have a couple on the shelf.
    Hope this helps
     
  3. great scott

    great scott 1/2 ton status

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    I pulled an adaptor from a 465/208 but it dosen't fit. It seems the adaptor is about 1" short, the splines bottom out before the adaptor and 205 do. Any ideas?
     
  4. Stephen

    Stephen 1/2 ton status Moderator Vendor

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    Sounds like this is a good time for a phone call if you're confused, I think you're trying to put the wrong parts together. The 465 to 208 adapter mates the 465 and 203 if you're using it for a Doubler application. The adapter to mate a 465 and 205 (late model round pattern style) is longer than the 465/208 adapter.
     
  5. great scott

    great scott 1/2 ton status

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    OK Stephen I feel like a litle kid at Christmas waiting for his new toy, so put me out of my misoury and tell me how much longer until my doubler shows up.
     
  6. Stephen

    Stephen 1/2 ton status Moderator Vendor

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    2 days or so I'm guessing. Probably not friday, most likely mon. or tues.
     
  7. great scott

    great scott 1/2 ton status

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    It's here! I came home today and found it on the porch. I will start on it tomorrow and with any luck all be running by monday.
     
  8. great scott

    great scott 1/2 ton status

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    How do I know were to set the original sm465/np205 adaptor on the 203 to get the round bolt pattern drilled and tapped in the 203. Is there a trick/gide or just mesure and eyeball it the best I can. I remember you telling me some thing about the D shaped shaft sticking out of the 203 and how I should do some thing to hold it in place, but I dont remeber what.
     
  9. great scott

    great scott 1/2 ton status

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    I finaly got it figured out, I hope? It's all put togather and I have all 3 ranges in both front and rear axles so I think its good to go.
     
  10. Stephen

    Stephen 1/2 ton status Moderator Vendor

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    Sorry, been covered up for a few days.
    Set the rotation with the Doubler adapter, that way both mounting feet are parallel and level.
    The half-flat in the idler shaft needs to be held in place with a tab bolted to one of the original mounting holes. It's kind of a fail safe to keep the shaft from spinning if you lose an idler bearing.
     

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