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Thread: 727 Swap

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    Wolf360rt's Avatar
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    Default 727 Swap

    Hey guys I just happen to have a small block 727 trans and a trans break just taking up space in my Garage and I know the 727 will bolt up to the Magnum block but, what else it needed as in the Flex Plate, converter and computer. And ive heard that your ET will drop by almost a second due to the lack of the rotating mass of the OD unit is this true? I also have a full race ready 8-3/4 axle with 4.56 gears and a full locker just sitting around and its wide enough to fit under the truck I dont give a damn about not having 6 bolt on the truck anymore. So What do you guys think should I do it or what?
    Derrick (Big D)
    2000 Black Regcab Dakota R/T (14.29 @ 95.77mph) soon to have a Garret Gt42-02 74mm turbo.
    1968 Barracuda Notchback Big Block Turbo E85 project.. S488 88mm Turbo

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    Just made that swap...Dropped 5 tenths the fist time down the track, but I was coming from a very good 46RE. I know I have room for improvement with the 727.

    You'll need a longer drive shaft, and a different tranny mount, and you will have to notch the trans case for the Crank trigger, and get the auto flashed out of the PCM...CELs will still be your friend.
    For strip, with limited street, do it. But the 4.56 gears and a 3 speed gonna get old if you spend much time over 60 mph.
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    Wolf360rt's Avatar
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    The truck is most likely gonna become an around town screw around toy so it wont spend much time above 60 unless im messing with someone..lol... and it wouldnt take much to swap out the 4.56 for something smaller.. Ive honestly never had the trans out of my truck myself to look at it is notching it a pretty easy job.. and does anyone sell the trans mount or is it something im gonna have to fab up.. Who can reFlash the pcm for me I have the performance pcm and dont wanna pay $450 for another one if I dont have to.
    Derrick (Big D)
    2000 Black Regcab Dakota R/T (14.29 @ 95.77mph) soon to have a Garret Gt42-02 74mm turbo.
    1968 Barracuda Notchback Big Block Turbo E85 project.. S488 88mm Turbo

    my mad ms paint skills

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    Quote Originally Posted by Adobedude View Post
    Just made that swap...Dropped 5 tenths the fist time down the track, but I was coming from a very good 46RE. I know I have room for improvement with the 727.

    You'll need a longer drive shaft, and a different tranny mount, and you will have to notch the trans case for the Crank trigger, and get the auto flashed out of the PCM...CELs will still be your friend.
    For strip, with limited street, do it. But the 4.56 gears and a 3 speed gonna get old if you spend much time over 60 mph.
    isn't there 727's out there with extra long tail shafts? i thought about a 727 when i had my trans done but my DS is long enough as it is.
    Fu·ror noun \ˈfyu̇r-ˌȯr, -ər\ : an angry or maniacal fit

  5. #5

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    if i remember right your have 3 diff. 727 tailshaft, you have a short, med. length one, and the long tail shaft.
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    408dakota's Avatar
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    I was running a 727 but then changed to a built 904. I think I picked up a little more rwhp just from it being a lighter mass just like everyone was saying but if you are buying new I would recomend the 904. Mine was built and dynoed tested at 750 hp so I will last me a while. It had a trans brake in it but the guy who bought it new kept it for his new upgraded trans.
    LA 408, W2 heads, Indy Intake, Bigs carb, long tube headers with 3" dual exhaust no cat, Built 904 manual valve body trans with 2800 stall.

  7. #7

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    heres some pics
    short:

    med:

    long:
    Last edited by red R/T; 01-11-2009 at 10:52 PM.
    88 samurai
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    Quote Originally Posted by red R/T View Post
    heres some pics
    short:

    med:

    long:
    nice

    anyone know the lengths of those compaired to the 46RE/RH's?
    Fu·ror noun \ˈfyu̇r-ˌȯr, -ər\ : an angry or maniacal fit

  9. #9

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    med length tailshaft is 20in and the long tailshaft is 26in

    i'll measurements for the 46re and the short tailshaft tomorrow
    88 samurai
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    Wolf360rt's Avatar
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    What Flex plate and converter will I have to run with this setup.. can I use the stock flex plate, and just a standard 727 converter.. and does the speedo read off the trans or the rear end or our trucks off the abs ring...
    Derrick (Big D)
    2000 Black Regcab Dakota R/T (14.29 @ 95.77mph) soon to have a Garret Gt42-02 74mm turbo.
    1968 Barracuda Notchback Big Block Turbo E85 project.. S488 88mm Turbo

    my mad ms paint skills

  11. #11

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    hey rohe, I have a spare 904 in the garage that needs rebuilding..I have 2 when I got my dart. Maybe it will find its way in my dak.
    Rob Dunn
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    Stock flex plate will work, but you'll have to ream out the bolt holes...You'll need a 727 converter.

    Speedo reads off the rear end.
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    Quote Originally Posted by Adobedude View Post
    Stock flex plate will work, but you'll have to ream out the bolt holes...You'll need a 727 converter.

    Speedo reads off the rear end.
    Thanks for the Info guys.. is there a trans mount that someone makes that I can just buy or will I have to fab one up.. and will the converter have to be a weighted or neutrally balanced one
    Last edited by Wolf360rt; 01-13-2009 at 02:05 AM.
    Derrick (Big D)
    2000 Black Regcab Dakota R/T (14.29 @ 95.77mph) soon to have a Garret Gt42-02 74mm turbo.
    1968 Barracuda Notchback Big Block Turbo E85 project.. S488 88mm Turbo

    my mad ms paint skills

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    Don't get the bracket from SMR, it's too short, and the drive shaft was too long.

    This guy mmacV001@odu.edu made the Trans mount I'm using now, it fit perfectly.
    Last edited by Adobedude; 01-13-2009 at 02:21 AM.
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    Quote Originally Posted by Adobedude View Post
    Don't get the bracket from SMR, it's too short, and the drive shaft was too long.

    This guy mmacV001@odu.edu made the Trans mount I'm using now, it fit perfectly.
    Thanks I will have to shoot him an e-mail..
    Derrick (Big D)
    2000 Black Regcab Dakota R/T (14.29 @ 95.77mph) soon to have a Garret Gt42-02 74mm turbo.
    1968 Barracuda Notchback Big Block Turbo E85 project.. S488 88mm Turbo

    my mad ms paint skills

  16. #16

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    i think speedo reads off of both trans and rear end sensors
    88 samurai
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    I have an 01, rear end sensor only.
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    i realize this thread is old but i had some questions. i have a 99 and i want to drop in a 904 or 727 and wondered if i could drop off some time in the 1/4? im runnin 12.85 on motor and wondered what i could realistically gain from a 727 swap? also any updated info on where to get a trans mount and driveshaft? is the speedo off the rear end in the 99's? thanks
    410, 10.3 comp pistons, P&P Eddies, 254 cam, 30lb injectors, sct tuner, 3800 viper stall, 4:56 yukon gears, hotchkis tvs, m1 4brrl, 58mm f&b tb, 1.7 rr, electric fan, jm longtube headers, B&M hammer shifter, Cope Racing Trans, Viper Brakes, SRT8 Seats, nx wet kit(100 shot)
    best time 11.32 @ 118 1.59 60' on spray(old motor). 11.76@115 n/a(new motor)
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    I think adobedude dropped 0.5 or so goind to a 4k stall and the 727. I think both helped equally to get him that much improvement.
    03 CC 4.7 NV3500

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    Quote Originally Posted by mtlcafan79 View Post
    I think adobedude dropped 0.5 or so goind to a 4k stall and the 727. I think both helped equally to get him that much improvement.
    I dropped that much off my 60' times.

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    SB440R/T's Avatar
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    Quote Originally Posted by Adobedude View Post
    I dropped that much off my 60' times.

    What stall were you running before?
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    2800 MSaine IIRC.
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    Quote Originally Posted by ADakotaRTGuy View Post
    What stall were you running before?
    2800 Msaine.
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    i actually talked to martin today and he said to go with a 904. less drag and would probably drop almost a second in the 1/4. i have a small block 727 laying around so im just gonna use that and have crt rebuild it with a 3800 stall. this seems almost to good to be true. drop a second by switching transmissions??? anyone runnin this with 4:56 gears and know what kinda rpm's i would be turnin at 70? would it be worth putting the 3:92's back in? thanks for the help
    410, 10.3 comp pistons, P&P Eddies, 254 cam, 30lb injectors, sct tuner, 3800 viper stall, 4:56 yukon gears, hotchkis tvs, m1 4brrl, 58mm f&b tb, 1.7 rr, electric fan, jm longtube headers, B&M hammer shifter, Cope Racing Trans, Viper Brakes, SRT8 Seats, nx wet kit(100 shot)
    best time 11.32 @ 118 1.59 60' on spray(old motor). 11.76@115 n/a(new motor)
    DD 07 SRT8 Charger 12.55@112

  25. #25



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    Quote Originally Posted by 99408kotar/t View Post
    i actually talked to martin today and he said to go with a 904. less drag and would probably drop almost a second in the 1/4. i have a small block 727 laying around so im just gonna use that and have crt rebuild it with a 3800 stall. this seems almost to good to be true. drop a second by switching transmissions??? anyone runnin this with 4:56 gears and know what kinda rpm's i would be turnin at 70? would it be worth putting the 3:92's back in? thanks for the help
    CRT 727 with 4.56 gears here....Don't even think about driving it at 70 mph, it's not a street friendly set up unless your street is under 50 mph.
    11.27 @ 118.23
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