Thread: 6T70 6-speed auto; has anyone swapped one into 3800?

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  1. #1 6T70 6-speed auto; has anyone swapped one into 3800? 
    GT Level Member April Thompson's Avatar
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    Has anyone ever swapped in a 6T70 6-speed automatic gearbox into a Series II/III-powered car? I can't find out whether the bellhousing is compatible, or if there's a retrofit adapter kit. Any thoughts? (and I know about the weak pre-2009 gearboxes)

    2004 Grand Prix GT2-clone A.K.A. the "Cybercar;" Galaxy Silver; 146K miles; RETROFITS: leather-wrapped steering wheel (w/audio controls) & shift knob; trip computer; map lights & dual lighted vanity visors; heated (?) leather seats w/ 10-way power driver's seat; ​HUD conversion
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  2. #2 Re: 6T70 6-speed auto; has anyone swapped one into 3800? 
    Turbo is the way to go. Fivefingerdeathpunch's Avatar
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    Would be a cool idea, but there is no way to control the transmisson.

    The computer can't control TCM inside the transmission.

    SMGPFC Member #1
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  3. #3 Re: 6T70 6-speed auto; has anyone swapped one into 3800? 
    GXP Level Member Turbocharged400sbc's Avatar
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    i would figure on wanting the 6t75/80

    but yes it will bolt up to the GM 60* v6 "FWD" bellhousing bolt pattern just fine as long as your not using the ford trans case
    ~James~ Psychotic Gearhead
    projects: 84 Cressida waGN~ 90 LN3 3800, equal length headers, T70, 89 700r4, misc parts,
    1994 Oldsmobile 442 (462ci-4wd-2 engines) L67/4t80e^2,
    00 Turbo Regal 608 fwhp 575ftlbs at 5500rpm, 98 WhippledRiv, 97 GTP
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  4. #4 Re: 6T70 6-speed auto; has anyone swapped one into 3800? 
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    Quote Originally Posted by Fivefingerdeathpunch View Post
    Would be a cool idea, but there is no way to control the transmisson.
    There is a way to control it though.
    Buying a standalone trans controller.
    They're out there for these units.

    The 6T80 is a beast… Would probably hold up to a 500whp turbo setup pretty well.
    Seeing as though its in a giant fwd Caddy with 450hp.
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  5. #5 Re: 6T70 6-speed auto; has anyone swapped one into 3800? 
    Donating Users 16MustangVet's Avatar
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    Quote Originally Posted by Fivefingerdeathpunch View Post
    Would be a cool idea, but there is no way to control the transmisson.

    The computer can't control TCM inside the transmission.
    Love how people used to say that about the 4t80 too.........
    Just because its not plug and play doesn't mean its impossible......
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  6. #6 Re: 6T70 6-speed auto; has anyone swapped one into 3800? 
    GXP Level Member Turbocharged400sbc's Avatar
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    iirc the newer transaxles are direct solenoid control without all the low/high pressure spool/shuttle valves of the older 4t hydramatics

    quite a different control architecture
    ~James~ Psychotic Gearhead
    projects: 84 Cressida waGN~ 90 LN3 3800, equal length headers, T70, 89 700r4, misc parts,
    1994 Oldsmobile 442 (462ci-4wd-2 engines) L67/4t80e^2,
    00 Turbo Regal 608 fwhp 575ftlbs at 5500rpm, 98 WhippledRiv, 97 GTP
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  7. #7 Re: 6T70 6-speed auto; has anyone swapped one into 3800? 
    Donating Users 16MustangVet's Avatar
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    iirc im not sure which trans it was but I thought Will from Overkill had done a 6 speed behind a 3800?

    More gears would be nice esp for a daily driver!
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  8. #8 Re: 6T70 6-speed auto; has anyone swapped one into 3800? 
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    I'd love to figure out a way to swap the XTS-V drivetrain into my Regal.
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  9. #9 Re: 6T70 6-speed auto; has anyone swapped one into 3800? 
    GT Level Member April Thompson's Avatar
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    But 3800s are 90* V6s; that's what I was curious about...
    And the 75/80s sound more stout, so anyone doing a conversion would be better off than the 70's 313 hp/280 lb-ft limits!

    2004 Grand Prix GT2-clone A.K.A. the "Cybercar;" Galaxy Silver; 146K miles; RETROFITS: leather-wrapped steering wheel (w/audio controls) & shift knob; trip computer; map lights & dual lighted vanity visors; heated (?) leather seats w/ 10-way power driver's seat; ​HUD conversion
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  10. #10 Re: 6T70 6-speed auto; has anyone swapped one into 3800? 
    Turbo is the way to go. BillBoost37's Avatar
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    Quote Originally Posted by SnowFlake View Post
    I'd love to figure out a way to swap the XTS-V drivetrain into my Regal.
    Turn a lot of wrenches
    I drink..so consider that when reading my posts.

    2010 Audi A6 Dual IC's
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  11. #11 Re: 6T70 6-speed auto; has anyone swapped one into 3800? 
    GT Level Member April Thompson's Avatar
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    Are both 3.8L & LS4 using the same bellhousing pattern? Because apparently the 6T70/5 should bolt up; I've been on the net a little more, and there are folks doing LS2/4 & 6T75 adaptations, as well as F40! One bloke put that combo in his Fiero! But I'm reading that as long as the Metric bolt pattern's there, it should​ work... though the starter for 5.3L might need an adapter...

    2004 Grand Prix GT2-clone A.K.A. the "Cybercar;" Galaxy Silver; 146K miles; RETROFITS: leather-wrapped steering wheel (w/audio controls) & shift knob; trip computer; map lights & dual lighted vanity visors; heated (?) leather seats w/ 10-way power driver's seat; ​HUD conversion
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  12. #12 Re: 6T70 6-speed auto; has anyone swapped one into 3800? 
    Donating Users 16MustangVet's Avatar
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    fiero people are nuts they always do swaps before everyone else catches on.
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  13. #13 Re: 6T70 6-speed auto; has anyone swapped one into 3800? 
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    I would NOT recommend a 6T70 6 speed transmission. I had one in my Saturn Aura with the 3.6L and I disliked it compared to the 4 speed. It seemed to want to shift at merging speeds, or any time I needed to move, and was not quick to shift. Also, Look up the 3-5-R Waveplate issue, which happens on a lot of them. I had it happen at 98k, but many people have had it happen as low as 25k on their cars.

    One positive with it though, is that you could do paddle shift with it. While not as exciting as driving a manual, if you've never driven a manual before, I hear it can be fun to use.
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  14. #14 Re: 6T70 6-speed auto; has anyone swapped one into 3800? 
    Turbo is the way to go. BillBoost37's Avatar
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    Somehow...I'm betting it shifts better than you driving a manual... hahahahaha that poor Acura
    I drink..so consider that when reading my posts.

    2010 Audi A6 Dual IC's
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