4T80E 3.11 to 3.71 swap - Page 5
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Northstar Engines and System Technical Discussion Discussion, 4T80E 3.11 to 3.71 swap in Cadillac Engine Technical Discussion; let me do some research and let you know what it will take....
  1. #61
    AJxtcman's Avatar
    AJxtcman is offline Cadillac Owners Connoisseur
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    Re: 4T80E 3.11 to 3.71 swap

    let me do some research and let you know what it will take.

  2. #62
    dalamak is offline Cadillac Owners Member
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    Re: 4T80E 3.11 to 3.71 swap

    You guys know if I can just manually shift the gears to get away without reprograming the shift points?

    And wil this Swap throw off the speedo Calibration?

  3. #63
    AJxtcman's Avatar
    AJxtcman is offline Cadillac Owners Connoisseur
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    Re: 4T80E 3.11 to 3.71 swap

    Quote Originally Posted by dalamak View Post
    You guys know if I can just manually shift the gears to get away without reprograming the shift points?

    And wil this Swap throw off the speedo Calibration?
    You can do some valve body work to control shifting better, bt the PCM does the other half. I would say it is maybe 70% & 30%.

  4. #64
    dalamak is offline Cadillac Owners Member
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    Re: 4T80E 3.11 to 3.71 swap

    Quote Originally Posted by AJxtcman View Post
    You can do some valve body work to control shifting better, bt the PCM does the other half. I would say it is maybe 70% & 30%.
    So does this swap Idealing require Valve body modifaction and PCM reprogramming?



    and the remark- "I would say it is maybe 70% & 30%" what do these % refer to?

    Thanks Tim

  5. #65
    AJxtcman's Avatar
    AJxtcman is offline Cadillac Owners Connoisseur
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    Re: 4T80E 3.11 to 3.71 swap

    Quote Originally Posted by dalamak View Post
    So does this swap Idealing require Valve body modifaction and PCM reprogramming?

    Thanks Tim
    NO on the valve body and Yes on the PCM.

  6. #66
    AJxtcman's Avatar
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    Re: 4T80E 3.11 to 3.71 swap

    Quote Originally Posted by dalamak View Post
    and the remark- "I would say it is maybe 70% & 30%" what do these % refer to?

    Thanks Tim
    If you were to disconnect the Trans connector and force the trans into first gear by powering up just the 1-2 shift solenoid the trans will still shift into 2nd via the valve body (fail safe). The PCM shift the trans by turning off the 1-2 shift solenoid.
    Then if you were in 2nd and you wanted to down shift into 1st by a toggle switch on the 1-2 shift solenoid it still wouldn't down shift. Fail safe in the trans.
    So you are out ice racing on a lake with a FWD Northstar Powered Caddy. You can't hold first gear unless you mod the valve body

  7. #67
    dalamak is offline Cadillac Owners Member
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    Re: 4T80E 3.11 to 3.71 swap

    Quote Originally Posted by AJxtcman View Post
    If you were to disconnect the Trans connector and force the trans into first gear by powering up just the 1-2 shift solenoid the trans will still shift into 2nd via the valve body (fail safe). The PCM shift the trans by turning off the 1-2 shift solenoid.
    Then if you were in 2nd and you wanted to down shift into 1st by a toggle switch on the 1-2 shift solenoid it still wouldn't down shift. Fail safe in the trans.
    So you are out ice racing on a lake with a FWD Northstar Powered Caddy. You can't hold first gear unless you mod the valve body
    lol Well that's a very interesting scenario to put it as, thanks,

    So under WOT accel, with an un modified Valve body, and not disconnecting the Trans connector, would the Higher Gear RAtio make the car shift gears to earlier or two late?

  8. #68
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    GizmoQ is offline The Last Good Gremlin
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    Re: 4T80E 3.11 to 3.71 swap

    Will you hurry up and move to Charlotte so you can start doing these mods on my ESC-V!

  9. #69
    mazda1949 is offline Cadillac Owners Member
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    Re: 4T80E 3.11 to 3.71 swap

    Hey guys , I've done this swap and the mechanical part is pretty simple. Of coarse I run a repair shop for a living and have been for about 40yrs or so.
    I noticed a big difference in the bottom end acceleration so it was well worth the swap.
    I have my northstar mounted in the rear of a Mazda pickup with a turbo. Plus I just put a 100 dry shot of of nitrous to get the turbo lag out of it. This thing is like a rocket!!!!!!!!!
    To all you out there old AJxtcman is the (Guru) on the caddy northstar. He's like EF Hutton, when he speaks you better listen. AJ has helped me with the ECM and many other things since I started my little project.
    I have a LS1 ECM running the engine and a stand alone transmission controller for the tranny.
    I have a youtube video here if you'd like to see it in action.[ame="http://www.youtube.com/watch?v=ZX7mEQPQfkY"]YouTube - Rear Engine Mazda pickup with a turbocharged Cadillac Northstar[/ame]
    Plus I have some pics on here of the swap.
    http://www.cadillacforums.com/forums...s1-pcm-11.html

  10. #70
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    Re: 4T80E 3.11 to 3.71 swap

    Quote Originally Posted by AJxtcman View Post
    Gears
    I am getting old. Does anyone know how to ID these?

  11. #71
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    Re: 4T80E 3.11 to 3.71 swap

    90% sure the little sun gear is the 3.71

  12. #72
    stoveguyy is offline Cadillac Owners Connoisseur
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    I swapped trans and removed diff cover cuz donor had crack in bolt boss. Used my old case cover. Still not sure how diff is driven by fwd trans. Ya I understand how mechanical things work but have never torn apart a fwd transaxle

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