4T80E 3.11 to 3.71 swap
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Northstar Engines and System Technical Discussion Discussion, 4T80E 3.11 to 3.71 swap in Cadillac Engine Technical Discussion; I have never done a swap from 3.11 to 3.71 gears. Bert want to wake up his DHS and make ...
  1. #1
    AJxtcman's Avatar
    AJxtcman is offline Cadillac Owners Connoisseur
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    4T80E 3.11 to 3.71 swap

    I have never done a swap from 3.11 to 3.71 gears. Bert want to wake up his DHS and make it a DTS. I think The VIN Y cams are equal if not better in 03. I did some checking and it looks like 2 part numbers is all I will need.
    #24205233 is a Carrier, Front Diff. INCLS 101 to 109.
    #08678825 is the sun gear
    Just the two parts. I can not say my price, but it is worth it. He has the 17" rims already. The difference between the 3.11 with 16" and the 3.71 with 17" is about 3 to 4 MPH at 70.
    I would need to set the ABS up for the 3.71 also.

    24205233 List $659.60 Trademotion.com $379.73

    8678825 List $144.56 Trademotion.com $83.22

    Has anyone done this?
    I can program it for 3.71

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    AJxtcman's Avatar
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    Re: 4T80E 3.11 to 3.71 swap

    Has anyone done this swap???????????????




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    eldorado1 is offline Cadillac Owners Connoisseur
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    Re: 4T80E 3.11 to 3.71 swap

    I have. Pretty simple. The only difficult part is getting the 10" snap ring out. That sucker is like 1/4" thick and difficult to get out of the groove.

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    Re: 4T80E 3.11 to 3.71 swap

    You might want to tell the computer about the change. I dunno what the side effects would be without it. I suppose you could always go to a dealer and get them to use the Tech Scan Tool on it.

    Let us know how it goes.

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    Re: 4T80E 3.11 to 3.71 swap

    Quote Originally Posted by eldorado1 View Post
    I have. Pretty simple. The only difficult part is getting the 10" snap ring out. That sucker is like 1/4" thick and difficult to get out of the groove.
    The ring gear is the same part # so the snap ring won't need to come off.
    correct?

  7. #6
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    Re: 4T80E 3.11 to 3.71 swap

    Quote Originally Posted by thu View Post
    You might want to tell the computer about the change. I dunno what the side effects would be without it. I suppose you could always go to a dealer and get them to use the Tech Scan Tool on it.

    Let us know how it goes.
    I work at a Dealer and can tune the PCM.

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    Re: 4T80E 3.11 to 3.71 swap

    I think that would be the idea situation. The LD8 engine (good torque) with the 3.71:1 final drive. That's how the Pontiac Bonne GXP came I believe (with the 275 hp engine and 3.71 transaxle).

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    Maxb49 is offline Cadillac Owners Member
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    Re: 4T80E 3.11 to 3.71 swap

    Is there a significant improvement in acceleration?

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    Maxb49 is offline Cadillac Owners Member
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    Re: 4T80E 3.11 to 3.71 swap

    By the way, what does this cost?

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    Re: 4T80E 3.11 to 3.71 swap

    Quote Originally Posted by jadcock View Post
    I think that would be the idea situation. The LD8 engine (good torque) with the 3.71:1 final drive. That's how the Pontiac Bonne GXP came I believe (with the 275 hp engine and 3.71 transaxle).
    2005 Pontiac Bonneville
    RPO....FV4...Ratio Transaxle Final Drive 3.71
    .........LD8...Engine Gas, 8 Cyl, 4.6L, MFI, V6, HO

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    eldorado1 is offline Cadillac Owners Connoisseur
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    Re: 4T80E 3.11 to 3.71 swap

    Quote Originally Posted by AJxtcman View Post
    The ring gear is the same part # so the snap ring won't need to come off.
    correct?
    If you can get by without removing that snap ring, then do it. I don't know to be honest, but I don't know why I would go through all that work if they were the same part

    But then again, maybe I just assumed they were different.

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    Re: 4T80E 3.11 to 3.71 swap

    Quote Originally Posted by eldorado1 View Post
    If you can get by without removing that snap ring, then do it. I don't know to be honest, but I don't know why I would go through all that work if they were the same part

    But then again, maybe I just assumed they were different.
    Is the snap ring the one for the sun gear that holds it in place on theoutput shaft?
    The ring gear has a large snap ring on it also, but I should not have to take it out.
    Warranty time is 3.5 hour to change it.

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    eldorado1 is offline Cadillac Owners Connoisseur
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    Re: 4T80E 3.11 to 3.71 swap

    No, the large one holding in the ring gear that eats small babies.

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    Re: 4T80E 3.11 to 3.71 swap

    Quote Originally Posted by eldorado1 View Post
    No, the large one holding in the ring gear that eats small babies.
    EH! I asked how much it cost! Answer!


    HAHA

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    Re: 4T80E 3.11 to 3.71 swap

    I have had so many of these tranys a part it is hard to remember. I am not talking about P0741, but the left aft shaft leak (3rd clutch housing failure) or 4th gear band burn up. I had a finnal drive out in the car once, so I know it can be done. I think 3.5 hrs is a lot of time for the way I did it. I have a special snap ring pliers for the output shaft snap ring.

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