"Sick Speed" GS project

Discussion in 'U-shift em' started by Stg'd 2Discover, May 30, 2019.

  1. Stg'd 2Discover

    Stg'd 2Discover Lumpty, Lumpty, Lumpty

    Over the years I've been slowly converting my 71 GS BBB from a street strip to a pro touring. Suspension, Brakes and Wheels are done.

    It was time to get into a manual gearbox with an overdrive that would still allow me extended highway travel and still be able to control the power within the range of my previously built street strip motor.

    A Tremec T56 Magnum, close ratio 6speed gear box was scored from a Chevelle owner whose project had to be liquidated and voila, Project "Sick Speed GS" was born.

    So far I have the following on order:
    - Billet BBB flywheel from American Powertrain
    -Quick Time BOP to T56 SFI bellhousing
    -Dual Disc McLeod RST clutch, (800 Hp)
    -Hydraulics for clutch
    -The "A body" Trans tunnel insert from "The Tin Man"

    I'll keep you posted on the progress.


    IMG_8656.JPG IMG_0563.JPG IMG_0563.JPG IMG_8656.JPG
    Last edited: Jun 1, 2019
  2. Stg'd 2Discover

    Stg'd 2Discover Lumpty, Lumpty, Lumpty

    Why I chose a 6 speed Tremec T56 Magnum over the 5 speed TKO 600:

    -The stock T56 Magnum has a 700ft /lb torque capacity to handle the 647 hp motor. Modified magnums are handling 1200+ hp. (who knows what's in the future)
    -The T56 single rail internal shift system works better than the 5 speed TKO 600's 3 rail system, which has been known to hang up on a 2-3 powershift. The TKO was essentially a modified truck trans. Even a stock T56 Magnum's shifter is precise & butter smooth.
    -The close ratio gear set of the T56 Magnum incorporates a 2.66 first, 1.78 second, 1.31 third, 1.00 fourth .80 fifth and .63 sixth. With a 3.73 final drive and 26" tire, this spread will launch well and allow to keep the revs better within the 308S cam power band when doing some serious driving. The .80 overdrive works better on rural back roads while the .63 is more for loafing at higher speeds on interstate type roads. It's nice to have the 2 options. A close ratio 5 speed with a .63 5th overdrive would result in too much of an rpm drop for my combination at 55-60mph.
    - The price was right and the unit is brand new unit with 0 miles.

    Last edited: Jun 1, 2019
  3. breakinbuick11

    breakinbuick11 Platinum Level Contributor

    Awesome project! Good luck with the conversion. Do you have more details on your pro-touring build?
  4. BillA

    BillA Well-Known Member

    Good luck with the pilot bearing. I had to use one that goes into the crank where the torque converter snout aligns. Dick Miller Racing sells them if you need one.
  5. Stg'd 2Discover

    Stg'd 2Discover Lumpty, Lumpty, Lumpty

    Thanks for the pilot bearing advice. I have a roller bearing and was going to hone the crank snout with a brake hone for a light interference fit.

    I' ll start a thread in the Pro touring section on the build
  6. sriley531

    sriley531 Buckle up, this could get rough....

    Sharp ride! That stance is ON POINT.
    docgsx likes this.
  7. gobuick

    gobuick Silver Level contributor

    Good choice on that clutch Tom, I have one behind my 560 & I love it.
  8. Clarkie

    Clarkie Well-Known Member

    That is going to be awesome!
  9. Julian

    Julian Well-Known Member

    I have been researching a lot on the T56/magnums.. modified..they can handle a lot. The pftizner ones handle 1500 WHP for a year to 3000ho I recall he said.."borrowed time". These are in Vipers.

    I am meeting one of the Pfizner distributors for consultation next week for my build
  10. Stg'd 2Discover

    Stg'd 2Discover Lumpty, Lumpty, Lumpty

    Anyone have info on ARP flywheel bolts correct for a BBB?

    A side profile pic of the car below.
  11. Taulbee2277

    Taulbee2277 Silver Level contributor

    Yep.. that’s badass
  12. Stg'd 2Discover

    Stg'd 2Discover Lumpty, Lumpty, Lumpty

    Pics of the parts that have been secured so far for the T56 magnum swap.


    IMG_0675.JPG IMG_0691.JPG IMG_0683.JPG
  13. Stg'd 2Discover

    Stg'd 2Discover Lumpty, Lumpty, Lumpty

    The hydraulics were from Modern Driveline

    Attached Files:

    Donuts & Peelouts likes this.
  14. Stg'd 2Discover

    Stg'd 2Discover Lumpty, Lumpty, Lumpty

    The McLeod dual disc RST

    Attached Files:

    Julian likes this.
  15. Julian

    Julian Well-Known Member

    And your pedal ratio is that going to matter?
  16. Stg'd 2Discover

    Stg'd 2Discover Lumpty, Lumpty, Lumpty

    The American Powertrain flywheel looks like a nice piece.

    Attached Files:

  17. Stg'd 2Discover

    Stg'd 2Discover Lumpty, Lumpty, Lumpty

    Modern Driveline sizes the hydraulic master/Tilton 6000 TB together to work with the stock pedal ratio drilling. The combination here uses a .7" master to provide a lighter pedal with a longer travel.
    Last edited: Jul 3, 2019
  18. Stg'd 2Discover

    Stg'd 2Discover Lumpty, Lumpty, Lumpty

    The Modern Driveline supplied Tilton 6000 series hydraulic Throwout bearing with threaded flange adaptor collar for the T56 Magnum.

    Attached Files:

  19. Stg'd 2Discover

    Stg'd 2Discover Lumpty, Lumpty, Lumpty

    I have two Hurst shifter boots. A conventional size and a Super Boot. Not sure which one will locate and look the best when the Tin Man prefab cover is installed.

    Attached Files:

  20. Stg'd 2Discover

    Stg'd 2Discover Lumpty, Lumpty, Lumpty

    The shifter handle is slightly offset to the left and in the middle position of the trans, close to the factory 4Speed location. Pedals are factory bolt in style for a 68- 72 BOP A body and have been welded for strength.
    Although is may not be necessary, I will fab a clutch pedal stop to ensure the master cylinder piston does not bottom out and the hydraulic TB won't overtravel the actuation of the clutch fingers.

    Attached Files:

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