6L80E to NP205

Discussion in 'The Garage' started by mattrains, Dec 17, 2012.

  1. mattrains

    mattrains MRAINS

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    I've searched the internet enough to overly confuse me. I have a 6L80E 4WD transmission out of an 08 Escalade and I need to mate it to an NP205.

    Do I need the figure 8 NP205 or the circle one?

    Do I use the TH400 to NP205 adapter and have it machined? If so what does that involve?

    Has anyone ever done this?

    Thanks for all the help

    Matt Rains
     
  2. mattrains

    mattrains MRAINS

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    I'm also open to a D300 if that's easier. Just sayin.
     
  3. Babaganoosh

    Babaganoosh 1 ton status Premium Member GMOTM Winner

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  4. drew4x4

    drew4x4 1/2 ton status Premium Member

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  5. mattrains

    mattrains MRAINS

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    Thanks guys. I think if I buy this adapter... http://www.advanceadapters.com/produ...-case-adapter/

    Swap the input shaft to this 32 spline shaft... http://www.advanceadapters.com/produ...r-amp-bearing/

    The make sure I have the NP205 w/ the round bolt pattern I can get it to mount up.

    Thing that blows my mind is the output shaft on the 4wd 6L80 is only 1.6" of threaded spline? How does it have room to fit the adapter and input shaft to the NP205? I'll give them a call.

    http://www.advanceadapters.com/downloads/509600.pdf
     
  6. Greg Ducato

    Greg Ducato 1/2 ton status Premium Member

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    What engine is this going behind? How will you control the trans? Sorry for the Hijack, just curious.
     
  7. 454Sub

    454Sub 5/8 ton status Premium Member

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    Its a complete Escalade drivetrain, the 6.2L to 6L80. I am really looking forward to this build, first I have ever seen it attempted with the new 6 speed. Curious to see its if its tough enough for the job.
     
  8. sweetk30

    sweetk30 selective wrench turner guy Premium Member

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    play with this and that tranny combo and see your crawl ratio. . . :whistle:

    http://www.grimmjeeper.com/gears.html

    if i had the cash i wanted to do that combo to my off road crew cab STUBBY project.
     
  9. Greg Ducato

    Greg Ducato 1/2 ton status Premium Member

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    Cool, looking forward to the results!:bow:
     
  10. Deuling

    Deuling "Official CK5 Post Whore" Premium Member GMOTM Winner

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    Why a 205? Why not a 208, or 241 with way better low gearing?
     
  11. miniwally

    miniwally 1/2 ton status Premium Member

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    Really this isn't anything that new now. There are several companies that can help you with the computer programming etc.

    I saw that pacific Fab had a complete 6.2L with 6L80/90 for sale a few weeks ago. They probably can help you, I know that there is one guy from Pirate that has been using this package for racing the last few years. I think he went through a few tough and expensive learning curves but he had it working.
     
  12. miniwally

    miniwally 1/2 ton status Premium Member

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    First gear in the trans is a 4.0 something, no need for a super low gear transfer case with that, provided it's for a regular wheeling type rig.
     
  13. mattrains

    mattrains MRAINS

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    I've got a 208 behind my current 454/th400 combo but the NP205 is absolute bomb proof. 70% of the top trucks competition run the 205 for good reason and with a 4:1 first in my transmission I'm not worried about the 2:1 in the 205.
     
  14. mattrains

    mattrains MRAINS

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    Oh yeah quick update... the th400 version of the 205 with the round bolt pattern bolts directly to the 6l80 if there isn't enough room they said I could use a clocking ring as a spacer. Problem solved. I'll update pics on my build thread when I get to installing one.
     
  15. 87blackblazer

    87blackblazer Registered Member

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    Any update on this build? I've got a 6L80E en route for my build, but I'm still trying to figure out the t-case options. The trans is coming w/ an MP1225, but it's a driver side drop.
     
  16. 6872xtc

    6872xtc make mine modified Premium Member GMOTM Winner

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    Subscribed and anxious as my Dad just picked up a 5.3/6L80E last week and we did not have a plan for it until I saw this thread..
     
  17. beags86

    beags86 Eastbound and Down Premium Member

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    So where's this hanging out now?
     
  18. 6872xtc

    6872xtc make mine modified Premium Member GMOTM Winner

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    It's gone down the road. It was a 2010 which I found out needed BCM VIN verification to let the transmission work. It would have required an '09 valve body in order to get a harness and ECM to run it.
     
    beags86 likes this.
  19. shady

    shady 3/4 ton status Premium Member

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    The 6l80 is one of the hardest trans to use in aftermarket. I've been researhrese the sh1t out of it because I loved the 5.3/6l80e combo in my '15 silverado. There's one company I found that does stand alone Allison controllers that said they MIGHT do a 6l80 controller. But at the moment from what I've read it's a lot of hassle to make it work.

    People do it,, but I don't know how :dunno:

    Wish I did because I'd LOVE to do it myself
     
  20. beags86

    beags86 Eastbound and Down Premium Member

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    Huh, I was kinda researching it myself. That's how I found up this old thread.
    I have a buddy with a 6L90E in a 86 Monte Carlo SS and he never said anything about it not working right or haveing trouble to get it to work.
    I am going to have to ask him.
     
    Last edited: Dec 13, 2018

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