Register now to get rid of these ads!

Technical Acceptable front axle spring shackle angle

Discussion in 'The Hokey Ass Message Board' started by 01mikep, Feb 5, 2016.

  1. 01mikep
    Joined: Jul 26, 2014
    Posts: 125

    01mikep
    Member
    from California

    My question is in reference to the angle of the front axle spring shackle and what is acceptable and what is not. There are plenty of posts on the HAMB stating that horizontal and vertical angles are not good and that 45 degrees is the ideal dimension.

    My angle sits at 27 degrees after installing a different spring stack. Before the swap the angle was 45 degrees. I replaced the previous spring in order to install a spring with more arch in order to raise the front of the car two inches. I had Morse Spring make up a new primary spring leaf. I removed my old primary spring and added more arch to the remaining leaves to match the new spring leaf. The center to center dimension between the eyes are the same for both springs. Installed with weight ,the shackle angle is 27 degrees though.

    Is that fine and I should forget about it or should I add a bit more arch to achieve the ideal 45 degrees.

    Below is my shackle as it sits.

    image.jpeg
     
  2. gimpyshotrods
    Joined: May 20, 2009
    Posts: 18,146

    gimpyshotrods
    ALLIANCE MEMBER

    Not good. One bump and the spring and shackle will smack into the batwing.
     
    olscrounger likes this.
  3. BJR
    Joined: Mar 11, 2005
    Posts: 6,905

    BJR
    Member

    Bounce it hard, I bet it hits the mount.
     
    olscrounger likes this.
  4. tfeverfred
    Joined: Nov 11, 2006
    Posts: 15,792

    tfeverfred
    Member

    Shackles should be parallel, unloaded. 45* loaded. I forget where I read that. You need a shorter spring.
     
    olscrounger and Harms Way like this.

  5. BLACKNRED
    Joined: May 8, 2010
    Posts: 333

    BLACKNRED
    Member

    Put your original main leaf back in, if you need more height add a spacer, if you need stiffer suspension add more leaves.
     
    clem likes this.
  6. The arch on your spring looks incredibly tall. They should ride much closer to flat. Your spring is way too long.

    The shackle angle isn't the main point, it's the quick look proof that everything is right. When the carried weight and pre load tension are correct the shackles will be at 45. When the length of the spring is correct the shackles will be at 45. there's more but I thing you can get the idea
     
    olscrounger likes this.
  7. 01mikep
    Joined: Jul 26, 2014
    Posts: 125

    01mikep
    Member
    from California

    I worked the spring pack a little at a time and shortened up the eye to eye distance by a bit over an inch. With no weight on the spring the shackle angle is near horizontal but with weight it rests at 38 degrees after repeated compression cycles.

    Yes 31 Vicky, the spring is a high arch design. I am working on a 60's altered type build. Many of the cars that inspired this build used this design. Below is as the car sits now.
    image.jpeg image.jpeg image.jpeg
     
  8. clem
    Joined: Dec 20, 2006
    Posts: 3,362

    clem
    Member

    Go with one of these options
     
  9. Kerrynzl
    Joined: Jun 20, 2010
    Posts: 2,283

    Kerrynzl
    Member

    They should be horizontal with about 1" of droop in the suspension [just enough to allow the wheel to drop into potholes]
    45 degrees loaded will get death wobble when the axle shifts sideways and one shackle is horizontal and the other side is vertical

    Jack the car up 1" from normal ride height and set the shackle angle from there
     
  10. gimpyshotrods
    Joined: May 20, 2009
    Posts: 18,146

    gimpyshotrods
    ALLIANCE MEMBER

    I am lazy. I would just take a couple of measurements, and then move the batwings (if they can be, without hitting the steering arm).
     
    Dirty Dug likes this.
  11. Kerrynzl
    Joined: Jun 20, 2010
    Posts: 2,283

    Kerrynzl
    Member

    You beat me to it ^^^^^ . I was going to suggest that , but thought I might get flamed off for it.
     
  12. gimpyshotrods
    Joined: May 20, 2009
    Posts: 18,146

    gimpyshotrods
    ALLIANCE MEMBER

    I am not afraid. Let 'em.
     
    lothiandon1940 likes this.
  13. tfeverfred
    Joined: Nov 11, 2006
    Posts: 15,792

    tfeverfred
    Member

    Excuuuuuuse me. I meant horizontal or parallel to the axle.:) And if you look at a PROPERLY set up system, the shackles are at 45* under load. If someone has an axle that's shifting sideways, they have a lot more issues than shackle angle. And while I don't mind being corrected, what is the shackle angle you suggest?

    Check this out. Seems to work.
    [​IMG]
     
    Last edited: Feb 6, 2016
    lothiandon1940 and olscrounger like this.
  14. Neat car.
    Not sure which cars inspired you, there's a bunch I'm sure.
    But these guys have a normal transverse spring but a dipped crossmember (raises ride height) and blocks on the springs ( also raises ride height.)

    image.jpeg
    image.jpeg

    In comparison, you're perch mount is setup to lower the stance or ride height.
    That perch is working against the direction you want to go. There is 8" or so to be had by flipping the the perch so it's under the frame.
    image.jpeg

    Moving the bat wings and spring mounts out closer to the wheels will give you more stability.

    The transverse spring is simple, but there's a lot involved. Pre load tension is a big part of it. As far as i know, these are the only leaf spring mounted in tension- so they are figured differently.
     
    Last edited: Feb 6, 2016
  15. 01mikep
    Joined: Jul 26, 2014
    Posts: 125

    01mikep
    Member
    from California

    I don't feel comfortable with lift blocks in front. I have been apart of the 4x4 world a bit and lift blocks up front are s no-no.

    A lower perch would be nice or a crossmember over spring would be nicest. It is not an option at this time. Batwings con move out no further.

    I'll stick with this one. 40-45 degrees is the target I see often and I get 39 degree shackles and 4 inches of down travel with no contact. My shocks only give me 2 1/2 inches up and down so I can't get 4 inches anyway.
     
  16. I figured the 4x4 lift spring thought process was being applied toward your ride height. Sadly the way a transverse spring supports the load and rates are different. They are different because the transverse spring is mounted in tension and lots of it. There's no preload tension in 4x4 springs, just the weight of the vehicle.

    Moving perch centers and altering preloads is going to be a design process.


    Look at like this,,,
    Normally When the spring goes flat from a jolt, or landing the shackles are still less than vertical. That's because the eye to eye measurement of the flat spring is what it is and within the perches. If your spring heads towards flat, how far beyond the hangers does it go?
     
    Last edited: Feb 9, 2016
  17. Harms Way
    Joined: Nov 27, 2005
    Posts: 6,869

    Harms Way
    Member

    Main leaf needs to be under a slight "Pre-Load" at a neutral un-sprung position.... Take a center to center measurement of your shackle mounts. Then take your center to center measurements on your shackles (Probably 1-1/2" CtoC) Add that together ,... so 3"...... Now subtract your 3" from the measurement of the shackle mounts..... And subtract another 1" to 1-1/2" for Pre-Load.... This will give you the "eye to eye" measurement you should have on your main leaf...( In a unpacked situation)

    Hope this makes sense to you,.... I know what I am trying to say... Just having a little trouble saying it.. o_O
     
    aussie57wag and lothiandon1940 like this.
  18. 3banjos
    Joined: May 24, 2008
    Posts: 472

    3banjos
    Member
    from NZ

    Just to open up an old wound. My dilemma is, one shackle sits at slightly more angle than the other.
    Could this simply be spring weak on one side, binding shackle one side. ????
    I've tweaked it over with a pinch bar, which had them equal. Go for blast and it goes back at odd angle.
    Your thoughts.
     
    redlineracer42 likes this.
  19. 3banjos
    Joined: May 24, 2008
    Posts: 472

    3banjos
    Member
    from NZ

  20. woodiewagon46
    Joined: Mar 14, 2013
    Posts: 1,863

    woodiewagon46
    Member
    from New York

    I think the Speedway, Speedy Tip, said it all. "The spring will be at a 40 to 45 degree angle when everything is properly installed and under load". Your set up is dangerous, something is going to break.
     
  21. gimpyshotrods
    Joined: May 20, 2009
    Posts: 18,146

    gimpyshotrods
    ALLIANCE MEMBER

    Is that a trailer spring?
     
  22. You should start your own thread.
    This one is muddled and nothing but confusion on who's talking about your car vs the original posters car.
     
  23. Probably, it's BS first then it's something else
     
  24. gimpyshotrods
    Joined: May 20, 2009
    Posts: 18,146

    gimpyshotrods
    ALLIANCE MEMBER

    Tie rod is out front, and for no apparent reason, too.
     
  25. mgtstumpy
    Joined: Jul 20, 2006
    Posts: 8,789

    mgtstumpy
    Member

    I'm with everyone else, it needs work. Apart from having incorrect Ackerman angle, do you propose to run friction or other shock absorbers on the front axle? In current configuration the frame will move side to side like a pendulum at the shackles when driving as the hairpins are parallel to frame. They need to be triangulated and wider at the axle to stop this from occurring. This motion will cause the steering drag link to continually push and pull as the suspension cycles.
    I would personally use larger diameter tubes on hairpins and steering with more wall thickness due to length. Plus the hairpins are in single sheer, what about using clevices? The rear hairpin mounting looks too light on for me as well. The only reason I say the above is that our engineering standards are a lot more stringent and our cars need to go through a certification process three (3) times prior to registration.
     
    Last edited: May 15, 2017
  26. gnichols
    Joined: Mar 6, 2008
    Posts: 10,974

    gnichols
    Member
    from Tampa, FL

    Could you remount the spring ahead of the axle, on mounts a little wider spaced than the batwings? Gary
     
  27. coilover
    Joined: Apr 19, 2007
    Posts: 651

    coilover
    Member
    from Texas

    Whenever I'm concerned about spring travel I use just the main leaf and then a jack to put the axle through it's whole travel range while checking for trouble spots. An air jack on the frame give full drop and a floor jack on the axle will raise to full compression height. If no binding or clashing with other parts through the full travel then stick the other spring leafs back in and drive the hell out of it. Remember to also check the travel in the left lock and right lock position as well as the straight ahead. Same on coils only you just set the springs aside while working suspension through full travel.
     
  28. quicksilverart46
    Joined: Dec 7, 2016
    Posts: 460

    quicksilverart46
    Member

    I agree in part with mgtstumpy. Tie rod must be behind the axle or Ackerman will be all F'd up. And these transverse springs will be all over the road because originally the wishbones were triangulated to the center . With split wishbones or parallel radius rods like this the axle will swing from side to side like a pendulum and be a handful to keep straight.!
    There are two ways to fix the wandering and handeling issue and that is with a panhard bar that locates the axle to the frame rail. The longer the better. If a short bar must be used then the suspension travel in compression and rebound Needs to be limited. Short shocks and stiffen up the spring pack will help.
    The second and rarely used remedy is to box in one side of the spring perch and eliminate the shackle . This is on one side only. This is an old dirt track/sprint car trick to improve handling and steering response. The main leaf acts as a panhard bar . The drawback is the spring is limited on that side and will act stiff but it is safe and will handle great .


    Sent from my iPhone using The H.A.M.B. mobile app
     
  29. 3banjos
    Joined: May 24, 2008
    Posts: 472

    3banjos
    Member
    from NZ

    Yeah, cheers for that. I think I'll try a new spring. When jacking evenly both sides from frame horns, the spring opens up (spreads apart)on one side quite a bit. Leaves stay together as they should on other.
     
  30. quicksilverart46
    Joined: Dec 7, 2016
    Posts: 460

    quicksilverart46
    Member

    P.S. Nothing wrong with the top mounted spring. If its going to be a Gasser than this is the right place to be. Check out the axle setup on very successful 1968 Hot Rod cover car "Tabasco" . The Blairs Speed built '55 Chevy D/Gasser!


    Sent from my iPhone using The H.A.M.B. mobile app
     

Share This Page

Register now to get rid of these ads!

Archive

Copyright © 1995-2021 The Jalopy Journal: Steal our stuff, we'll kick your teeth in. Terms of Service. Privacy Policy.

Atomic Industry
Forum software by XenForo™ ©2010-2014 XenForo Ltd.