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Hot Rods Banjo 4 bar Triangulated Rear?

Discussion in 'The Hokey Ass Message Board' started by 2935ford, Aug 26, 2017.

  1. 2935ford
    Joined: Jan 6, 2006
    Posts: 2,992

    2935ford
    Member

    On a stock A chassis (no kick up) with a '39 banjo, open drive.......possible?

    No happy at all with the ride of my current radius rod, modern shocks, buggy spring setup.
    Harsh.....is too kind a word!
     
  2. Removing a few short leaves from the rear spring will soften the ride.
     
  3. 2935ford
    Joined: Jan 6, 2006
    Posts: 2,992

    2935ford
    Member

    ^^^^
    Yup, already been done......no help.
     
  4. BLACKNRED
    Joined: May 8, 2010
    Posts: 263

    BLACKNRED
    Member

    Are your shocks the right length
     
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  5. Torana68
    Joined: Jan 28, 2008
    Posts: 1,036

    Torana68
    ALLIANCE MEMBER
    from Australia

    if harsh is the problem changing the way the diff is located wont help, its spring rate and more likely a shock issue.
     
  6. 2935ford
    Joined: Jan 6, 2006
    Posts: 2,992

    2935ford
    Member

    Ok, I'm pretty sure I see my issue. I did not notice this until now.
    I had previously changed out the main rear leaf once already for a shorter length as the first was too long.
    Once installed it looked good shackle angle wise but I still wasn't happy with the ride. It was better but not what I wanted so I just let it go and continued to just bang, crash down the road. Later we found a "floating" rear wood mounting block that had not been bolted down. Did that, which got rid of some of the noise but not help the ride.
    Now as you see, the shackle angle is very bad which to me means the replacement shorter main leaf is not short enough. Looks also like I have a leaking shock but the shock movement appears to be Ok as they are mounted in the middle of the up and down movement.
    I will also have to shorten the next leaf up.

    So, is there a formula for main leaf length...... perch c to c width/shackle "stretch" in order to get and keep the 45 degree angle?
    Are my perch mounts too low?
    a spring 002a.jpg
     
  7. Looks like the shackle is riding on the axel.Shorter main maybe?
     
  8. 2935ford
    Joined: Jan 6, 2006
    Posts: 2,992

    2935ford
    Member

    ^^^^
    Not quite but close. Yes, another shorter axle.
     
  9. treb11
    Joined: Jan 21, 2006
    Posts: 3,140

    treb11
    ALLIANCE MEMBER

    do I perceive TWO second leaves in the picture? If so loose one for sure.
     
  10. 2935ford
    Joined: Jan 6, 2006
    Posts: 2,992

    2935ford
    Member

    ^^^^^
    No just the dirt illusion of two.....only one there.

    Ok, so my measurements are this:
    perch: C to C is 47 1/2"
    shackles: C to C 1 1/2"
    My main leaf un sprung reverse spring eye C to C measurement should be ????
     
  11. Generally with tube shocks you're looking more for 2/3 up travel and 1/3 down, not 50/50.
     
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  12. 2935ford
    Joined: Jan 6, 2006
    Posts: 2,992

    2935ford
    Member

    ^^^^
    Ok thanks....did not know that.
     
  13. 2935ford
    Joined: Jan 6, 2006
    Posts: 2,992

    2935ford
    Member

    I understand attaching the A rear main leaf spreads 6" (3" per side) for tension leaving the shackles parallel until the body weight is applied then everything settles to the 45 degree......?????
     
  14. BenD
    Joined: Mar 5, 2001
    Posts: 1,590

    BenD
    Alliance Member

    That main leaf is "reversed eye" which is hitting the axle/mount when compressed. Reversed eye lowers the car, but is causing your problem. A stock main leaf would roll counter clockwise at the shackle, if that makes sense?


    Sent from my iPhone using H.A.M.B.
     
  15. alchemy
    Joined: Sep 27, 2002
    Posts: 13,538

    alchemy
    Member

    There is no formula for calculating the correct spring length. There are too many variables. A large spring with three curves in it, a car with who knows how much weight on it, and adding and removing various leaves. All these different things will make your car totally different than any other out there.

    Just eyeballing that pic makes me think an inch out of each side would be good. Take your main leaf to a spring shop and have them make the exact same shape and thickness, but two inches shorter.
     
  16. 2935ford
    Joined: Jan 6, 2006
    Posts: 2,992

    2935ford
    Member

    ^^^^^
    Thanks.
    As mentioned....I have already replaced a spring with a narrower one but only to have it settle and still be too long.
    I believe I did not account for the necessary tension or stretch of the spring and once weight was applied.....so, I just keep trying having them make me leaves until one of them finally works!
    I think I have a plan for the right width.....see what happens.
     
  17. alchemy
    Joined: Sep 27, 2002
    Posts: 13,538

    alchemy
    Member

    And every leaf you pull out to soften the ride will also allow it to settle making the spring wider.
     
  18. 2935ford
    Joined: Jan 6, 2006
    Posts: 2,992

    2935ford
    Member

    ^^^^
    Yup, that I understand but I now have the right amount of leaves so I just need the right main leaf
    Thanks
     
  19. I am about as far from an early Phord guy as you can get so bear with me, but I am a long time hot rodder and have built my share of many different suspensions and the principles don't change. That spring stanchion looks bent, but maybe that is the way it is supposed to be? Looks to me if it were straight up, the spring would clear the rear axle tube nicely and the shackle would lay out properly and allow the spring to work properly. If you need those 2 long second leaves to carry the load, that is preferable to short ones that stiffen the ride a lot more.

    Oh, and if a shorter main leaf is the answer you don't need to buy a new one. If you have a lot of trucking in your neighborhood, there is a spring shop to service them. They can roll a new end on that spring or even reverse the ends for a few shekels.
     
    Last edited: Aug 28, 2017
  20. Yes, that's the way it's supposed to be.
     
  21. 2935ford
    Joined: Jan 6, 2006
    Posts: 2,992

    2935ford
    Member

    ^^^^^
    Yup. Thanks.
    I purchased those perches as they look. They mimic originals except they get welded to the axle housing but a little closer in than stock.
     
  22. I think you are on the right track, the shackles need to be a bit flatter to work properly.
     

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