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More 1/4 elliptic rear suspension questions

Discussion in 'The Hokey Ass Message Board' started by Tony Travers, Apr 29, 2011.

  1. Tony Travers
    Joined: Jan 11, 2010
    Posts: 61

    Tony Travers
    Member

    G'day
    I'm planning a small light vaguely lakes inspired T. I've looked at ways to get the chassis lower than traditionally but don't want to step the rear and have decided one option maybe rear 1/4 elliptics. I've searched the HAMB and I a question. Why do I need a shackle or an eye on the axle?
    On the assumption my chassis rails aren't parallel so it tapers from front to rear about 6" if I ran rear 1/4 elliptics they would likewise be wider at the rear. Why can't I mount them fixed at each end without an eye or shackle. The vertical movement (yes I know the rear axle would be traveling in an arch) would be no different to so called NASCAR truck arms, the side ways movement would be contained by the splayed layout and any body roll would be minimized as the springs would twist and resist it. I don't think the springs would wind up any worse than a set up with top arms - I'm not planning any big power. I saw a pic of a '20's something Buick (?) that was not unlike what I'm proposing but it would have had a torque tube.
    Cheers
    Tony
     
  2. Ghost28
    Joined: Nov 23, 2008
    Posts: 2,874

    Ghost28
    Member

    I don't know if I could answer your question, but here is a 26 buick rear assembly.
    [​IMG]
     
  3. Ghost28
    Joined: Nov 23, 2008
    Posts: 2,874

    Ghost28
    Member

    And another. The buick mounting at the axle is a rotating unit that with the torque tube is needed, but with a u joint setup on your third member it most likely would not be needed. I am gonna use this same stock setup in the 26 but without a torque tube rear, but mount the spring on the bottom of the axle without the rotating part.
     

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    Last edited: Apr 29, 2011
  4. Malcolm
    Joined: Feb 9, 2006
    Posts: 6,589

    Malcolm
    ALLIANCE MEMBER
    from Nebraska

    Here's a couple shots of the rear QE setup on my Roadster chassis.
    I think it's similar to what you are talking about --- no shackles.


    [​IMG]


    [​IMG]




    Malcolm
     
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  5. Ghost28
    Joined: Nov 23, 2008
    Posts: 2,874

    Ghost28
    Member

    Malcolm. I really like that setup. CLEAN
     
  6. FiddyFour
    Joined: Dec 31, 2004
    Posts: 8,983

    FiddyFour
    Member

    you need the shackles due to the change in spring "length" relative to suspension travel... bind and broken springs will result otherwise
     
  7. Malcolm
    Joined: Feb 9, 2006
    Posts: 6,589

    Malcolm
    ALLIANCE MEMBER
    from Nebraska


    I'm going to try to prove you wrong... we'll see what happens :)
     
  8. Tman
    Joined: Mar 2, 2001
    Posts: 29,861

    Tman
    Member

    Two words TORSION BARS
     
  9. FiddyFour
    Joined: Dec 31, 2004
    Posts: 8,983

    FiddyFour
    Member


    i like what i see, and i really, TRULY hope i am proven wrong bud
     
  10. The37Kid
    Joined: Apr 30, 2004
    Posts: 17,715

    The37Kid
    Member

    I was going to suggest you Google Bugatti GP or Type 40 for a photo of their rear spring setup, then I looked at Malcolm's photos. That setup looks very much like a Bugatti only the springs are in front of the axle. Is there a build thread on that chassis? Really like the looks of the tube work. Bob
     
  11. The37Kid
    Joined: Apr 30, 2004
    Posts: 17,715

    The37Kid
    Member

    That may be why the Bugatti setup has an oval eye in the main leaf that allows the bolt to slide back and forth a good inch if memory is correct. They had a torque arm that ran from the center section of the rear to the trassmission to center things. :)
     
  12. 28dreyer
    Joined: Jan 23, 2008
    Posts: 670

    28dreyer
    Member
    from Minnesota

    Here's my Speedcar with a set of splayed 1/4 ellipticals with the axle end free to slide in a containment open ended box which is built on to the radius rod which also terminates with the big end of a connecting rod that allows the axle housing slight rotation during travel.

    This is a torque tube drive line and we have included a panhard rod as the springs are narrow and the cornering forces high.

    We have also mounted the spring and special U bolts to a pad that has a short piece of sawed off torsion bar welded to the pad that passes through a bushed spud welded through the tube frame with a splined torsion bar stop on the inside of the frame to provide ride heighth adjustment.

    Are you in the Barossa Valley?
     

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    Last edited: Apr 29, 2011
  13. FiddyFour
    Joined: Dec 31, 2004
    Posts: 8,983

    FiddyFour
    Member

    it would work, and WELL, if and if... both the spring and the bar move in a parallel arc and hit the apex at the same instant... i cant tell if nicks is going to be like that at ride height or no...

    if im wrong, i;d rather be told what the reality is so then i know more than i do now
     
  14. The37Kid
    Joined: Apr 30, 2004
    Posts: 17,715

    The37Kid
    Member

    28dreyer, that is the exact same design used on a Type 59 Bugatti, much better IMO that the earlier oval eyed spring hole. Ever see a Dreyer Wiggle Front End, with two long springs and Model T Ford axle parts?
     
  15. Mr48chev
    Joined: Dec 28, 2007
    Posts: 17,763

    Mr48chev
    ALLIANCE MEMBER

    This T modified was in one of the recent Rod and Custom issues. Here are the photos I took at the Yakima Vintiques run last year.
    [​IMG]
    [​IMG]
    [​IMG]
    [​IMG]
    [​IMG]
    It does have shackles because it runs split bones and the shackles keep the spring from binding as they don't act as a lower half of a fourbar.

    This is a different modified with quarter elliptic springs on the front.
    [​IMG]
    [​IMG]OSLYN05RUN062.jpg[/IMG]
    [​IMG]
    Ok, I've been wrong for the past 7 years, the black car does have split bones with the spring mounted without shackles. I always had it in my mind that it used something more like the lower half of a fourbar so the spring acted as the top half. I'm inclined to think that the spring might want to bind a bit on this one.
    It will work fine the way Malcom showed with his but with the split bones like the two I showed going without a shackle would probably cause the spring to bind.
     
  16. fossilfish
    Joined: Dec 16, 2010
    Posts: 315

    fossilfish
    Member
    from Texas

    Just look at a 1959 Austin Healey Sprite rear axle assembly. They were 1/4 elliptic. One of the better road race designs ever. I am putting a version on my bobber. Works great for drag racing too...if you set it up properly
     

  17. You only need shackles if the axle is located by other means.
    Four bar, hair pins, triangulated 4 link, etc.

    If the springs help locate the axle, with no binding,
    you don't need shackles.
     
  18. FiddyFour
    Joined: Dec 31, 2004
    Posts: 8,983

    FiddyFour
    Member

    read my next post... explains my thought better
     
  19. 28dreyer
    Joined: Jan 23, 2008
    Posts: 670

    28dreyer
    Member
    from Minnesota

    This is a Dreyer 1/4 elliptical front end on a mid 30's Big car but propably not what you are referring to. Don't see any Model T parts here.

    Notice the straight tubular front axle ala today's sprint cars and midgets. I'm not enough of a Dreyer person to know when he might have started doing that and how long it might have continued.
     

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  20. jelp
    Joined: Oct 1, 2009
    Posts: 17

    jelp
    Member
    from australia

    Jaguar MK11 cantilever rear suspension the front half of the springs mount inside the chassis rails a bit smoother than 1/4 ellipticals due to longer effective length
     

    Attached Files:





  21. Ever see a triangulated 4 bar, where the
    upper and lower links are different lengths ?

    How about a 3 bar, with a short upper link ?

    Or a Torque Arm, typically longer than the lower links ?


    Forget "parallel arcs and the apex" whatever that is.
     
  22. bct
    Joined: Apr 4, 2005
    Posts: 1,432

    bct
    Member

    imagine malcomes 1/4 elip. flattened out .........the length could change by over an inch....the top link isn't going to change ....pinion is going to move down when hitting a bump possibly when the drive shaft is level
     
  23. Tony Travers
    Joined: Jan 11, 2010
    Posts: 61

    Tony Travers
    Member

    G'day
    I just had a read of your reply's and of my post again. What I didn't make really clear is by fixing the arm and both ends without a shackle or an eye I would be using the spring also as the only suspension arm - No top arm or radius rods. If you imagine the two link layout under a c10 pick-up or NASCAR but using the springs as the lower arms.
    And to who ever asked I'm in the Barossa.
    Cheers
    Tony
     
  24. DrJ
    Joined: Mar 3, 2001
    Posts: 9,401

    DrJ
    Member

    Early Bug-eye Sprite setup, similar to what Tony just described:

    [​IMG]
     
  25. [​IMG]


    Notice the upper and lower links are different lengths.
     
  26. No parallel arcs and/or apexes.
     
  27. krylon32
    Joined: Jan 29, 2006
    Posts: 3,278

    krylon32
    Alliance Vendor
    from Nebraska

    I did a rear suspension like Malcolms in a deuce roadster I built back in the early 80s I used a 40 front spring split in half with the triangulated bars/no shackle and I see the car every year at the LARS and it's still going strong with about 150K on the speedo. I currently do the 1/4 rears with a Posie kit with shackles and P&J ladder bars and to date I haven't had the need to add a panard as the spring is captured in the bracket which prevents side movement.
     
  28. falcongeorge
    Joined: Aug 26, 2010
    Posts: 9,922

    falcongeorge
    ALLIANCE MEMBER
    from Surrey BC

    Have you calculated how much that "change" in length actually is? I have, I think you are in for a surprise. I am doing basically the same thing (no shackles) but with the torque tube as the upper link. Guys always get lost in the engineering on here, and forget to do the math.
     
  29. If the springs are relatively flat, the length change is nothing to worry about. I'd be real careful about the combination of a fixed mount on the torque arm and any serious arch in the spring pack. The torque arm doesn't work the same way as a set of upper links that will allow some pinion angle change....
     

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