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Possible to have a 4L80E doubler?

Discussion in 'OffRoad Design' started by Sledge, Nov 9, 2001.

  1. Sledge

    Sledge Registered Member

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    I'm building a '72 Jimmy in which I was planning to mate a 4L80E to a NP205. Since I'm going to be playing the specialty adapter game anyway, I was wondering if it was posible (w/o spending the earth) to use a Doubler to mate the tranny and t-case(s). Anyone know if this is feasible, and how it might be done? (Machine a TH400-203 adaptor?)
     
  2. Stephen

    Stephen 1/2 ton status Moderator Vendor

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    In a '72 K5, you may want to look into what you would have to do to get a 1 3/8" output shaft in the 4L80, then use the 1 1/8" factory TH400 to NP203 adapter plate. If you can spare another 1.5" or so, you could use the factory 4wd adapter housing and drill and tap the bolt pattern into the front face of the NP203 and bolt it directly together. This latter method is going to be the cheapest and easiest, but does cost a little length.

    Making the world better, one truck at a time.
    SW-ORD
    <a target="_blank" href=http://www.offroaddesign.com>www.offroaddesign.com</a>
     
  3. Sledge

    Sledge Registered Member

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    Stephen, can you elaborate on the second option? I'm planning on using one of your shackle flips and a CV driveshaft in the rear so I doubt that an extra 1.5" of length will mess up the angles too badly. When you say "use the factory 4wd adaptor housing..." which housing are you refering to? Do you mean a tranny to t-case adaptor, or something else. Sorry if I'm being dense here. I appreciate you taking the time to spitball ideas here on the board.
     
  4. Stephen

    Stephen 1/2 ton status Moderator Vendor

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    The factory 4L80 to 241 adapter is about 2.5" thick and has a round pattern at the back that's easily matched up to the NP203. The shaft stickouts work out well with that technique, and the parts are readily available. Basically all you have to do is install a 32 spline input gear in the NP203 and re-drill the face of the 203 case to take the round bolt pattern.

    Making the world better, one truck at a time.
    SW-ORD
    <a target="_blank" href=http://www.offroaddesign.com>www.offroaddesign.com</a>
     
  5. ccj8008

    ccj8008 1/2 ton status

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    My 91 1 ton Silverado has a 4L80E mated to an NP205. This was the factory set up.
     
  6. 84_Chevy_K10

    84_Chevy_K10 Banned

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    Are you sure it's not a TH 400? I didn't think 4L80E's came around until about '93?

    Tim
    '84 Chevy K10, lifted, loud, fast, and 3/4 ton axles
     
  7. ccj8008

    ccj8008 1/2 ton status

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    Positive. 1991 was the first year that I know of that the 4L80E was used. Unfortunately, this was also the last year for the Dana 60 front end.
     
  8. Sledge

    Sledge Registered Member

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    Thanks for the info, I also thought the 4L80 debuted in '93. I wonder if I could find a NP205 and adaptor at a bone-yard and skip the Advanced Adaptors custom stuff. Worth a look anyway.
     
  9. Stephen

    Stephen 1/2 ton status Moderator Vendor

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    I don't think you need Advance for anything that has to do with factory parts, the factory put this together at some point so we can use factory parts to do it again.

    Making the world better, one truck at a time.
    SW-ORD
    <a target="_blank" href=http://www.offroaddesign.com>www.offroaddesign.com</a>
     
  10. Sledge

    Sledge Registered Member

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    You're right, of course, Stephen. I got some bad info regarding the starting year of the tranny. It should always be cheaper to use factory parts than go custom. Looks like I'll be calling the j'yards. :)
     
  11. Stephen

    Stephen 1/2 ton status Moderator Vendor

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    Depending on what you're looking for the wrecking yards may not be a good place to find it, but when you start looking at spending $500 on adapters, you can buy new or old stock factory stuff pretty easily.

    Making the world better, one truck at a time.
    SW-ORD
    <a target="_blank" href=http://www.offroaddesign.com>www.offroaddesign.com</a>
     
  12. Sledge

    Sledge Registered Member

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    Where would you recommend, if not a wrecking yard? Any advice is appreciated.
     
  13. Sledge

    Sledge Registered Member

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    Duh, I didn't read you post very well. New old stock. That's how I got the '98 tranny I'm trying to use.
     
  14. Stephen

    Stephen 1/2 ton status Moderator Vendor

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    Measure the output shaft stickout and call us and we'll see what we can do. I'm guessing the best way to do this is with a standard GM 4" adapter and the long input in the NP205. We'll see.

    Making the world better, one truck at a time.
    SW-ORD
    <a target="_blank" href=http://www.offroaddesign.com>www.offroaddesign.com</a>
     

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