Gear Vendors on 1969 t400

Discussion in 'The "Juice Box"' started by ribuick, Aug 12, 2022.

  1. ribuick

    ribuick Well-Known Member

    I have a quick question, Who has put a Gear Vendors on a 1969 400 stage1 ? Just finishing a frame off to a bone stock car and the 3.64 rear just wants another gear. I did not want to change out the original trans, so I just purchased a Gear Vendors unit. Curious if any one else has done this. What can I expect form this unit. I have 7 weeks before it gets here. Thanks
     
  2. Bens99gtp

    Bens99gtp Well-Known Member

    I put one on a ss 1500 big block pickup truck, it was very straight forward, great tech support....... .78 od ratio so a 22% drop
     
  3. Marv Marksberry

    Marv Marksberry Well-Known Member

    8ABD86E7-29EB-4DA1-BB89-FBF151CE917D.png

    My son added the Gear Venders unit to his Switch Pitch 400. He said the instructions were easy to follow and it works great.
    He is running 3:90 rear end gears and has a 4,000 SP stall converter.
     
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  4. mbryson

    mbryson Owner of Ornery grandma Buick

    My ears are perked up. Thanks for posting. Looking hard at doing this for my '72
     
  5. cjeboyle

    cjeboyle Gold Level Contributor

    Following
     
  6. LARRY70GS

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

    Adding a GV to any THM400 is very straight forward. I've had mine since 2006. I am currently running one of JW's 9.5" converters, 3.73 gears, and a 28" tire. Final drive is 2.76.
     
  7. mbryson

    mbryson Owner of Ornery grandma Buick


    That sounds like a total win? Sounds like I should start saving a couple bucks for the GV overdrive. My car needs PLENTY of work before the OD becomes a priority but I think it'd be pretty nice
     
  8. LARRY70GS

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

    Yes, the combination works really well. The converter is efficient enough to deal with the final drive ratio. It is responsive everywhere. Drops my RPM on the highway by 600 RPM.
     
    ribuick likes this.
  9. cjeboyle

    cjeboyle Gold Level Contributor

    Larry, what is your RPM at 70 mph? Right now with a JW converter and 3.08’s I am at 2800 or so at 70. I believe you are running 3.73’s which would be what I am looking to change to when adding a GV. Not trying hi hijack the thread.
    Thanks
    Cliff
     
  10. LARRY70GS

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

    Approximately 2500-2600 RPM. That is with 28" tires.
     
  11. rkammer

    rkammer Gold Level Contributor

    Larry, I'm considering the GV for the future. Did you have your factory driveshaft cut to fit behind the GV or did you have another shaft fabricated?
     
  12. LARRY70GS

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

    I had another driveshaft made. It was cheap enough. The shop I used told me how they wanted me to measure.
     
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  13. rkammer

    rkammer Gold Level Contributor

    Steel or aluminum?
     
  14. LARRY70GS

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

    Steel.
     
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  15. rkammer

    rkammer Gold Level Contributor

    How does package GV package address the need to extend the stock speedometer cable and do they provide the correct drive gear so we don't have to change the driven gear?
     
  16. LARRY70GS

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

    It's unnecessary to extend the cable. There is an extension cable because of the signal generator. You can see it in this picture, part number 9 and 10.

    GV.JPG
     
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  17. LARRY70GS

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

    The GV instruction manual has a chart for speedo gears. It is based on the GV 15 tooth DRIVE gear.

    GVSpeedoGearsR.jpg
    I use a 40 tooth Black gear, 3.73 and 28" tire.
     
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  18. Dan Hach

    Dan Hach Well-Known Member

    What's the net extension of the transmission with that unit? It looks like about 5-6".
     
  19. LARRY70GS

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

    Last edited: Aug 24, 2022
  20. Dan Hach

    Dan Hach Well-Known Member

    Wow, I didn't think it was that much. My Wife always said I was bad at estimating how long things are.

    That looks like a really nice upgrade if you can make it work.
     
    bostoncat68, Waterboy and patwhac like this.

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