6 Speed Manual Options

Discussion in 'Street/strip 400/430/455' started by Harley Biggers, Sep 29, 2020.

  1. I am curious if there is a common 6-speed manual trans used with 455 Buick engines.

    I was thinking of the T56 Magnum. I am pretty sure it can handle the torque but how much work would it be to bolt one up to a 455 if at all?

    If not what options do I have? I have 3.42 gears in the rear right now. Looking for better highway mpg while still having the low end, neck-shattering torque.
     
  2. hugger

    hugger Well-Known Member

    There are a couple vendors that offer kits,..around $5 to 6k for everything
     
  3. hugger

    hugger Well-Known Member

    I would suggest a 4l80 auto and then a gear swap to a 410
     
  4. 87GN_70GS

    87GN_70GS Well-Known Member

    The 5 and 6 speeds will require mods to the trans tunnel to fit
     
  5. 70 GMuscle

    70 GMuscle Plan B

    What’s involved with this for a 70 Huggie bear?
     
  6. Stg'd 2Discover

    Stg'd 2Discover Lumpty, Lumpty, Lumpty

    I did the T56 magnum swap last year with my big block complete with dual disc clutch, scattersheild & hydraulic clutch. See "U- shift em" section and my thread "Sick Speed Project" for my complete install, photos and parts chart.
    Very fun car to drive.
    IMG_1237.JPG

    Tom
     
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  7. hugger

    hugger Well-Known Member

    Not much really straightforward,...nothing special needs to be done to the trans as its a brute,..there are several control units available now,..or just a simple manual valve body

    Its only a .73 or something close iirc but you could get away with a 410 easily
     
  8. Stg'd 2Discover

    Stg'd 2Discover Lumpty, Lumpty, Lumpty

    If you enjoy shifting gears I suggest a T56-Magnum close Ratio box. It has a super strong end loader design to handle 700 ft/ lbs torque and the shifts are very good. Having a .80 5th & .62 ratio 6th are a bonus for cruising.

    IMG_0675.JPG
     
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  9. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    It's a .75 4th OD gear. It would make the 4.10 gears would be like 3.08 in OD

    My Gear Vendors is .78
     
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  10. hugger

    hugger Well-Known Member

    Thats they way to go imo,...could run 90mph all day
     
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  11. 70 GMuscle

    70 GMuscle Plan B

    I like this idea for my Chevelle someday.
     
  12. Stg'd 2Discover

    Stg'd 2Discover Lumpty, Lumpty, Lumpty

    If you now highway cruise at 2500 rpm and kept your 3.42 ratio with a typical say 27.5" tire, the close ratio T56 Magnum will be 75mph in 5th and 94in 6th, or you could loaf along the interstate at 1700rpm doing 65mph in 6th. The 2.66 first gear is better takeoff than any of the Muncie transmissions that came with our cars.

    attached link: BBB GS Tremec T56 Magnum swap, if interested.
    http://www.v8buick.com/index.php?threads/sick-speed-gs-project.346534/
     
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  13. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    X2, and you can run a lock up converter as well. I would have went that way if it was affordable and do able back in 2006 as it is today. The 4L80E is a nice transmission.
     
  14. That sounds like exactly what I wanted. You said a typical 27.5 tire. You mean actual tire size right? I have a set of hub centered '71 Buick rally rims so I am guessing that they are the standard size. Right now it runs right at 3000 rpm at 67mph. I really want to have something that I can drive long distances on the highway if I need to.

    I plan on taking it down to Charleston where I go to school from where I live in Nashville. I have to plan out a route that has as little highway as possible. I'm fine with it taking along time. I am just pumped for the journey.
     
  15. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    Stock tire height was more like 26.4"- 27". The G60-15 was 26.44", the G70-14 was 26.82", and the G78-14 was 27.06"

    RPM = 336/tire height X rear gear X MPH, Add in 150-200 RPM for converter slip for automatics.
     
  16. Bens99gtp

    Bens99gtp Well-Known Member

    hell that's about what my motorhome turns now while towing the trailer.....that ford v10 with overdrive and 5.13 gears......


    What trans do you have now in there.....I'm sure gear vendors makes an adapter to fit just about any transmission and you would drop about 700ish rpms.

    The system is super easy to install....only takes about a day, the have your driveshaft shortened
     
  17. Stg'd 2Discover

    Stg'd 2Discover Lumpty, Lumpty, Lumpty

    27.5" equates to actual tire diameter. It looks like your tire is smaller in diameter if you rev 3000 at 67mph.
    At any rate the T56 magnum double overdrive will bring your cruising rpm down so you can take the interstates.
     
  18. Stg'd 2Discover

    Stg'd 2Discover Lumpty, Lumpty, Lumpty

    Assuming your tire diameter actually is closer to 26" with the 3.42 axle (due to the 67 mph at 3000)
    Your present same combo with the t 56 Magnum equates to the following:
    60 mph in 4th gear would be 2650 rpm 1.00 ratio
    60 mph in 5th gear would be 2120 rpm .80 ratio
    60 mph in 6th gear would be 1700 rpm .62 ratio

    Hope this reference helps you see the significance any overdrive has on hyway travel comfort, MPG and decreased engine wear
     
  19. SageSenior

    SageSenior Well-Known Member

    I went with a 200-4R...easily fits in the 65 with no tunnel modification...run 275/60 x 15 MT DOT drag radials, with 4:30 rear gears as a driver in my 65. Runs 70 MPH at 2,400 rpm.
    I considered the 4L80, but I knew that tunnel mods were needed to fit in a 1970 body, and concluded that the 65 body probably would need more mods than the '70...so we went with the 200-4R.
    Love it.
    Tony Saggese
     
  20. buicksWILD

    buicksWILD Well-Known Member

    Got any pics of those drag radials stuffed beneath the car?
     

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