"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

    So I decided to keep the existing G Force X-member and modify it for correct install height and make it a true bolt in. The rigidity of this unit helped with the frame twisting that I had with my drag launches and I really like this unit for it's high HP rigidity. Unfortunately G Force does not make a T56 style member for GM's A body, but they do have one for a G body, which I studied for its differences.

    The existing member used with the TH 400 is shown below:
    To modify it, I ground off the end tabs & made some 1/4" thick 2"x 3" angle pieces 3 1/2 " wide to replace them.
    The new assembly with relocated angle tabs.
    The new ends are fastened with high strength 3/8" capscrews into tapped holes. This also facilitates the T56 magnum removal and install.
    Last edited: Dec 14, 2019
  2. Carcrazy

    Carcrazy Dan Whytock

    Very nice. I will have to stop by this summer and check out the setup.
  3. Stg'd 2Discover

    Stg'd 2Discover Lumpty, Lumpty, Lumpty

    Crossmember is in and the 3 1/2" dia. driveshaft was shortened to 48 1/2" from 54 1/2 " . A local roundy round powertrain place turned it around in less than half a day including balance.

    I had a slight mishap with the T56 Magnum vent tube elbow that connects to the case, so I made a more robust one on the lathe from an old 90 degree fuel line fitting.
    Last edited: Dec 22, 2019
  4. Stg'd 2Discover

    Stg'd 2Discover Lumpty, Lumpty, Lumpty

    I have a potentially functioning install! Driveshaft is in, clutch safety switch is wired and the clutch hydraulics work.

    Initially there was still a slight issue with an airlock in the hose between the reservoir and master that caused an initially soft pedal and then it went very very hard. Once that was sorted out, the pedal could even be moved by hand and was consistent in movement. The clutch itself releases the clutch about an 1.5" from the floor when we rotated by the driveshaft, just as it is supposed to on this setup.

    For now the tunnel sheet metal is only held in place (for position) by two screws and will be secured later by butt welding or screws if I decide to fab a maintenance opening for the shifter.

    The position of the Hurst offset lever to the steering wheel is in a nice proximity for driving. Shift and steering are close together. IMG_1021.JPG

    I installed a Prothane poly trans mount to replace the tired rubber mount.
    Next is more interior button up, driveline geometry final adjustment and an electronic reverse lockout module that permits reverse gear below 5 mph.

    breakinbuick11 likes this.
  5. Stg'd 2Discover

    Stg'd 2Discover Lumpty, Lumpty, Lumpty

    This is what I chose to function my Reverse gear lockout.

    T56 magnums have their shift pattern setup so reverse gear is up and over to the very right. This is also close to where 5th gear resides. To prevent accidental shifting Tremec supplies a solenoid internally to lock this out, but it can be overpowered manually with very hard force. On late mode factory 6 speed cars the onboard computer enables a low speeds only override to permit an easy shift into R. For swappers some people have used the 12 vDC brake pedal signal or wired up a manual accessory switch to make this work, but Samoco has a neat standalone device that uses the electronic Vehicle Speed Sensor (VSS) output to achieve what the factory has done.

    What you don't want to do is have the Reverse lockout disengaged while driving and chance the possibility of going into it at speed.
    (Imagine what may happen, when hitting your brakes on the freeway and down shifting from 6 to 5 and going into R by mistake. )




    Last edited: Jan 9, 2020

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