Register now to get rid of these ads!

Rear Spring Over Suspension

Discussion in 'The Hokey Ass Message Board' started by keeper, Dec 6, 2012.

  1. keeper
    Joined: Jul 24, 2006
    Posts: 398

    keeper
    Member
    from So Cal

    I had a thread talking about this a while back but for the life of me I cannot find it so I would like to get the discussion going again since I am finding some time here and there to work on my car.

    I don't know why but I am just banging my head against a wall to figure this out. I have z'd the frame in the back and I am running a spring over the axle.

    This is pretty much where I sit now.

    IMG_2012-07-06 001404_3.jpg

    And this is what I was thinking about for the bars.

    rear bars.jpg


    - Am I just way off?
    - Can I just run the bottom bar if I have a spring over set up?
    - Do I need to triangulate if I have a transverse spring?

    Please help me work this out.
     
    Last edited: Dec 6, 2012
  2. Beau
    Joined: Jul 2, 2009
    Posts: 1,884

    Beau
    Member

    Lots of ways to skin this cat. Four bar being the least traditional and ugliest.

    I have a load of info and links to threads in my build for how I did it. I'm making a "wishbone" for the rear.

    Basic ladder bars seem to be the way most people go for your type of build.
     
  3. You can run a single link on each side, but you still need 2 attachment points at the axle (like a hairpin) to restrain pinion angle. DO NOT run triangulated uppers with the buggy spring in back. The weight of the car should hold the axle centered if you have the shackles at a 45deg angle at ride height.
     
  4. NortonG
    Joined: Dec 26, 2003
    Posts: 2,117

    NortonG
    Member Emeritus


  5. keeper
    Joined: Jul 24, 2006
    Posts: 398

    keeper
    Member
    from So Cal

    What are the concerns if I have to run such short bars?
     
  6. I used radius rods for my ladder bars.JW[​IMG]
     
    Last edited: Dec 7, 2012
  7. need louvers ?
    Joined: Nov 20, 2008
    Posts: 12,903

    need louvers ?
    Member


    Pinion angle change mostly. The shorter the arms are, the greater the curver the rear end will go through as it moves up and down.
     
  8. keeper
    Joined: Jul 24, 2006
    Posts: 398

    keeper
    Member
    from So Cal

    I should not have too much travel with a transverse spring, do I need to be concerned about travel?
     
    Last edited: Dec 6, 2012
  9. need louvers ?
    Joined: Nov 20, 2008
    Posts: 12,903

    need louvers ?
    Member

    The problem you'll have with the short arms and a transverse spring is that the arc the rear travels in will have a tendency to put the spring itself into a bind. A super short arm like that is better suited to a suspension medium such as coils where there is some fore to aft movement available. Also, as drawn, with a shorter upper arm than lower arm, you are running in actually two arcs as the rear travels. With the shorter arc on top, the pinion angle will want to point down as the rear rises. Trying to keep the lengths all the same, and as long as possible is usaully key with a four bar set up. for the sake of packaging, I would really say take a look at the Pete and Jakes ladder bar set up on the link above. That with a transverse spring works really well.
     
  10. Beau
    Joined: Jul 2, 2009
    Posts: 1,884

    Beau
    Member

  11. keeper
    Joined: Jul 24, 2006
    Posts: 398

    keeper
    Member
    from So Cal

    Am I reading it right that they are saying this will work? Some times building this thing I feel so over my head.
     
  12. need louvers ?
    Joined: Nov 20, 2008
    Posts: 12,903

    need louvers ?
    Member

    That is a good link for further info. The one thing though that strikes me with all of the setups on that thread is the length of the four bars used in all of those set ups. My deal with the set up shown here is how short and compact everything is. ElPolacko touches on that a bit in his explanation of how it works. He does a lot of torque arms and single lower arms and has this deal down, but part of it is how long stuff is.

    Just as a side point, the picture of the '46 he and I put together almost twenty years ago did indeed use a triangulated four bar of unequal length, but I have always been convinced that part of what made it work soooo well(and that thing handled beautifully!) was how the spring was mounted to the axle. We used stock Corvette mounts along with the Corvette cross leaf spring. Instead of being shackled at the ends of the spring, it is hung from a single center point both top and bottom, so it can work with the arc or pinion change without binding. ext time you see a seventies Corvette, lookat how the spring is hung from the suspension and you'll see what I mean.
     
  13. need louvers ?
    Joined: Nov 20, 2008
    Posts: 12,903

    need louvers ?
    Member

    Actaully one of the last pictures on that thread shows the Corvette type link that I'm yammering about.

    keeper, I'm not telling you it won't work. it's just not ideal as far as setting stuff up, and I personally see a couple of places that could be a problem. And, that's not from a safety issue, just a performance stand point. A trianglulated four bar with a transverse spring is sort of a belt and braces approach that is a bit redundant. Also, greater length will reduce the amount of arc to the point that everything will "free up" and be much more mobil and resisitant to bind. You might look at the linked thread a bit closer at the picture ElPolacko posted of transverse springs with a three link or torque arm. The torque arm especially will be easier to package and work very well with you rear spring.
     
  14. keeper
    Joined: Jul 24, 2006
    Posts: 398

    keeper
    Member
    from So Cal

    I really appreciate all of the help, I'm afraid I might have put my self in a position of limited options.
     
  15. fiftyv8
    Joined: Mar 11, 2007
    Posts: 5,394

    fiftyv8
    Member
    from CO & WA

    Yeah, Kevin, that Pete & Jake setup would be the way to go if it will work with what you have done so far.
    Any progress pic's coming up?
     
  16. Kerrynzl
    Joined: Jun 20, 2010
    Posts: 2,906

    Kerrynzl
    Member

    3-link it!

    Run parallel arms under the axle and forward.
    Then have a triangle top link off the centre of the rear end.

    There is enough arch in the spring to clear the upper link ,and you won't need a panhard with this set-up
     

    Attached Files:

  17. need louvers ?
    Joined: Nov 20, 2008
    Posts: 12,903

    need louvers ?
    Member

    He doesn't need a panhard with a properly set up transverse spring in the first place.
     
  18. 26 roadster
    Joined: Apr 21, 2008
    Posts: 2,019

    26 roadster
    Member

    Why couldn't you move the upper bar over on the rear end and make it the same length as the lower and through bolt it in the frame?

    then no arc to bind the spring
     
  19. Beau
    Joined: Jul 2, 2009
    Posts: 1,884

    Beau
    Member


    Why?

    Either use a 4 link and coil overs, or use ladder bars with what you have.

    Why are you so stuck on using a 4 link?
     
  20. chopt top kid
    Joined: Oct 13, 2009
    Posts: 959

    chopt top kid
    Member

    To use the shorter four bar set-up with the traverse spring, all four bars need to be equal lengths. The shorter bars on top with the longer bars on the bottom will cause the rear axle to rotate as the suspension moves up and down, which will bind the rear spring and shackles. Ladder bars however are mounted solid to the rear axle and pivot farther forward. They do not allow the axle to rotate, but let it swing thru a large arc without binding the rear spring and shackles.
     
  21. keeper
    Joined: Jul 24, 2006
    Posts: 398

    keeper
    Member
    from So Cal

    Yes I will be starting to post more pics again. Finally getting back into the swing of things, but I only get to work on it when my boys are asleep. There is not a lot of quiet work on a hot rod.

    Would this set up still work if the base of the "Y" was significantly longer?

    I'm open to just about anything but I don't want to start from scratch on my chassis. I have a very narrow rear end so I can't get ladder bars to the outside of the frame. The kick up blocks me from running inside the frame.

    If I move the top bar axle mount in so the bars are the same length, as mentioned earlier, would that work? Then it is a triangulated 4 link though, right?
     
  22. Beau
    Joined: Jul 2, 2009
    Posts: 1,884

    Beau
    Member

    Last edited: Dec 7, 2012
  23. NortonG
    Joined: Dec 26, 2003
    Posts: 2,117

    NortonG
    Member Emeritus

    "I have a very narrow rear end so I can't get ladder bars to the outside of the frame. The kick up blocks me from running inside the frame."

    I don't see why you couldn't use the pete & jakes bars I posted running close to the inside of the frame rails. They don't have to use the center mount in the picture on thier website.
     
  24. Dreddybear
    Joined: Mar 31, 2007
    Posts: 6,084

    Dreddybear
    Member

    Hey man, I have spring over. I'm running those p&j ladders. You can see them in this pic. If you look closely you can see that I cut down the bars to clear under the body. Honestly cant see why you cant do what I did..

    [​IMG]
     
  25. Dreddybear
    Joined: Mar 31, 2007
    Posts: 6,084

    Dreddybear
    Member

    In this pic you can sorta see how the ladder bars were modified. Cut the center out and squeeze them together then weld it back together and then bend (or cut n weld) the back up to match the holes.

    [​IMG]
     
  26. chopt top kid
    Joined: Oct 13, 2009
    Posts: 959

    chopt top kid
    Member

    Is the picture you put up in the first post your chassis??? The distance between the mounting brackets of a P&J's ladder bar is only 31 1/4", and they have two styles of forward mounting crossmembers, one installs above the driveshaft and the other installs below???
    But , if you're set on four-bars, here's another thread: model t 4-bar insanity check

    P.S. Lookin' good Dreddybear!!!
     
  27. need louvers ?
    Joined: Nov 20, 2008
    Posts: 12,903

    need louvers ?
    Member

    Errr, well basically, yes they do have to. The whole idea behind that arrangement is the triangulation presented by mounting them close together at the front like that. It can be done other wise, and truth be told I HAVE done them out on the frame rails, but it is not a great compromise.
     
  28. need louvers ?
    Joined: Nov 20, 2008
    Posts: 12,903

    need louvers ?
    Member

    Keeper, I'm not sure why you are so tied to having a triangulated four link on this car. A transverse spring when properly set up really doesn't need a panhard rod or any form of side to side control. That's part of the beauty of Henry's basic design. More with less and all, ya know? Beau's picts (although personally I would add a single torque arm into the mix, but that's just me) and DreadyBears or both good ways to go with this deal that will ride well, handle well and be trouble free for as long as you own the car. Look very close at both.
     
  29. Cali4niaCruiser
    Joined: Aug 30, 2005
    Posts: 599

    Cali4niaCruiser
    Member

    This sounds familiar! I'm working my way through the same issues right now. I too am building a heavily z'd / low car with a transverse rear spring. I first built a ladder bar suspension (bolted solid to the axle). I too, only have room for rather short trailing arms. When finished the ladder bar idea was incredibly stiff! I knew it would break something down the road, so I scrapped it. I retrofitted my setup with a single bushing in the back (allowing the axle to pivot) and I am adding a 3rd link on top to keep the pinion angle constant. From all the reading and advice I've got off of here, low cars like ours dont do so awesome with transverse springs and four links. Although not traditional, I wish I would have just gone with a 4 link and coil overs. Something to think about.
     
  30. keeper
    Joined: Jul 24, 2006
    Posts: 398

    keeper
    Member
    from So Cal

    So you think I could just use the spring and a torque arm on each side. I think this is would be what I wasn't to go after if possible. Simplest and cleanest solution, I like " more with less"

    I'm assuming I should make the torque bars adjustable, right?
     

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.