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Can any rear radius rod handle SBC/open drive line combo?

Discussion in 'The Hokey Ass Message Board' started by poboyross, May 11, 2011.

  1. 8flat
    Joined: Apr 2, 2006
    Posts: 1,392

    8flat
    Member

    Ditto..
     
  2. chop32
    Joined: Oct 13, 2002
    Posts: 1,077

    chop32
    Member

    I guess I should have been more clear when I talked about cutting the bones loose and mounting them seperately. The idea goes along with 8flats Idea...basically building my own 4 link (doesnt really need to be triangulate since im running a cross spring) and just using the ford bones as the lower arms (with bushings added at each end) and standard 4 link upper bars.

    Hotrodpro: thats the picture I was refering to earlier, thanks for posting it again!
     
  3. lorodz
    Joined: Jul 26, 2009
    Posts: 3,727

    lorodz
    Member

    i used stock 40's radius rods on the rear spread to the inside of the frame like you would do to the front split bones and found when i depress the clutch the rear twists alot wich is from the torque, and isnt very good to drive it like that so im going to make a torque arm kinda running like the torque tube straight down the middle from the banjo to the cross memeber which should keep the rear from twisting ..look up thunderbirdesq's builf he built one and im sure it works well. its a must
     
  4. Ford rear radius arms were not designed to control pinion roll with accel and decell. The torque tube took care of that. Because of that, breakage will happen when the parts are missused.
     
  5. F&J
    Joined: Apr 5, 2007
    Posts: 13,222

    F&J
    Member


    If you mean your 40 radius rods are now parallel? , that will cause a rod to break. Does not matter if you add a torque arm, does not matter if it's open or closed drive, it will fail at some point.

    Most likely will fail at the rear forging. there are old pics somewhere on hamb...a super nice A roadster broke the forging and the owner said no warning signs, it just broke in two.
     
  6. lorodz
    Joined: Jul 26, 2009
    Posts: 3,727

    lorodz
    Member

    can you find that picture so i could see how it was set up?
     
  7. Hnstray
    Joined: Aug 23, 2009
    Posts: 12,355

    Hnstray
    ALLIANCE MEMBER
    from Quincy, IL


    Yes, Hot Rod Pro.........you are!..........very, very nice !!

    Ray
     
  8. 8flat
    Joined: Apr 2, 2006
    Posts: 1,392

    8flat
    Member

    That's a good point, I wondered that myself. Are they weaker than your typical tubing used in 4-link systems? Maybe there's a significant wall thickness difference?
     
  9. A while ago someone posted some pictures of a suspension setup that achieved the look
    of split rear bones; but was designed to permit proper movement. The axle brackets
    were built like the lower brackets for a triangulated 4 bar. The stock Ford wishbones
    were attached to these brackets with a urethane bushing and the forward end was
    was mounted with a Ford tie rod end for appearance. There was torque arm mounted
    rigidly to the side of the banjo housing with the front end mounted with a urethane
    bushed shackle arrangement. The shackle compensated for the length difference between the torque arm and wishbones. This was a buggy spring set up and did
    not have a panhard bar. It looked like a good system; but I don't know how it
    worked out. I saved the pictures; but not savvy enough to post them. Have to get
    my kid to show me how someday.
     
  10. poboyross
    Joined: Apr 29, 2009
    Posts: 2,142

    poboyross
    Member
    from West TN

    Sounds cool...PLEASE, if you can get those pics posted, PLEASE DO!!! :)
     
  11. Zombie Hot Rod
    Joined: Oct 22, 2006
    Posts: 2,452

    Zombie Hot Rod
    Member
    from New York

    [​IMG]

    '37 rear radius rods on the bottom, tubing on the top, and a gusset in the middle.

    The top links keep stress off of the cast ends of the radius rods under acceleration.
     
  12. 39cent
    Joined: Apr 4, 2006
    Posts: 1,569

    39cent
    Member
    from socal

    HOT ROD PRO,s is close to what I did on my 32 tub in 1959. Only I welded some ribs on top and bottom of the arms. Used a 49 Mercury X member [turned upside down], and hooked up the 32 ball just like his.

    After checking this problem out for awhile, I have changed my outlook and would use a torq arm for triangulation. I think its best if the torq is controlled off the differential just like the old torq tube does. This way both thrust, and housing twist is controlled properly.
     
    Last edited: Jul 21, 2011
  13. 8flat
    Joined: Apr 2, 2006
    Posts: 1,392

    8flat
    Member

    Here are the pics and response from Rich:

    On the drawing I think the connection to the axle should not be in line with the tube; but offset like the ones pictured.

    The picture called "torque arm pictures 3" shows a different set up with the forward link
    going down instead of up. I think the original post said it worked either up or down,
    which ever worked best for the application.

    Hope this info helps
     

    Attached Files:

  14. The wall thickness does't play into the puzzle. Ford had used a FORMED TUBE WELDED ON THE UNDERSIDE, and a welded component--butt welded, butt welded.
    Add some math into what I know.
    Driveshaft parts that fit into a tube, NOT PIPE, have a correct press fit tolerance of .007" tp .010". It doesn't matter if the tubing is .065 or .259 thick. Because of that, the press fit keeps the weld together too. A butt weld CANNOT do the same job as a press fit.
    Ford did not make torque rods or wishbone welds to be press fit shaped or parts made to fit the shapes.
    Usage, application, modifications will cause either fun or breakage. Grab your welding hat and make something happen. You will have one or the other.
    With that, nobody said you can't make elongated triangle gussets with bolted pickup points and welded to the bones to take the torque that Henry didn't allow for. Road condition induced torque is as much as a factor as the powerplant and road induced whatever will tear up stuff as well as a heavy foot on the loud pedal.
    Triangles are very good in the right application.
     
    Last edited: May 13, 2011
  15. justpassinthru
    Joined: Jul 23, 2010
    Posts: 524

    justpassinthru
    Member

    Here is a few photos of the rear suspension that Ionia Hot Rod Shop is fabricating for my somewhat mid 50s period correct Flathead powered 32 Ford. I dont like the look of ladder bars or bones on the outside of the frame, so this is what they came up with. I think they addressed any and all issues of strength or twist. They also added a panhard bar that is not shown. I just hope my Flathead has enough horsepower to pull all that weight!
     

    Attached Files:

    29EHV8 likes this.
  16. Hnstray
    Joined: Aug 23, 2009
    Posts: 12,355

    Hnstray
    ALLIANCE MEMBER
    from Quincy, IL


    Workmanship looks nice enough but I think they "missed the boat" on the engineering/geometry issues with bones rigidly mounted to the axle housing at the rear. They did improve considerable on what is often done in this regard, by moving the bones front pivots inboard, but, In my opinon not close enough with the rigid rear mounts. IF they had provided a pivot on the bones at the rear as well, with the third link handling axle 'wrap', they would have pretty well nailed it. But then, IF my Aunt had balls, she'd be my Uncle. :eek:


    Ray
    Ray
     
  17. chop32
    Joined: Oct 13, 2002
    Posts: 1,077

    chop32
    Member

    Ive learned alot from this thread, but it seems that everyone is thinking that the axle wrap (or the upward rotation of the pinion) under acceleration is the only thing thats breaking parts. Every time the chassis raises up on one side and down on the other, such as pulling out of a gas station driveway at an angle, a twisting stress is imparted to the rigid axle-to-wishbone mounts, which will eventually cause them, or the forged wishbone ends, to bend or break. (see pic in post #4).

    The only way I can see to get around this, without rubber mounting the bones to the axle, is a ball pivot like Hotrodpro used, or making some sort of frame mounted, stationary driveshaft hoop and having a larger hoop which rides on bearings around it, and mounting the forward point of your bones to this outer hoop with rubber bushings, tie rod ends or heim joints. Rather cumbersome and impractical, and not very good for controlling axle wrap, but it I feel it illustrates my point.
     
  18. racemad55
    Joined: Dec 14, 2005
    Posts: 1,149

    racemad55
    Member

  19. Rpmrex
    Joined: Nov 19, 2007
    Posts: 664

    Rpmrex
    Member
    from Indiana

    Apparently your not going to use the rearend I sold you? Im gathering that you think it's ugly? It would solve all your problems except the need for a pan hard bar.
    You must be looking to build something older looking, If thats the case,more power to ya. ;)
    How's the build coming? SBC I guess?
     
    kidcampbell71 likes this.
  20. poboyross
    Joined: Apr 29, 2009
    Posts: 2,142

    poboyross
    Member
    from West TN

    ? No, I'm using the rear end. I just figured out that I don't like the look of the hairpins or ladder bars in general...hence why I was asking about swapping them out for radius rods...move the mounts out to the outer perimeter of the axle.

    HOWEVER, I must admit, if I had the cash to spring for an original Halibrand Quickchange...man, I don't think I could pass it up! XD The Bishop/Tardel book has me spoiled.....I've figured out that I *do* like older looking stuff, if it fits within budget. I'm going to be rolling on 35 wire wheels and such.

    Doing the SBC, its just easier and cheaper to deal with. I'm apparently not hard core enough to put a flathead in it....oh wait, I do like spending my money on frivolous things like food and bills! XD lol......
     
  21. poboyross
    Joined: Apr 29, 2009
    Posts: 2,142

    poboyross
    Member
    from West TN

  22. VoodooTwin
    Joined: Jul 13, 2011
    Posts: 3,453

    VoodooTwin
    Member
    from Noo Yawk

    How about using something like this, in conjunction with a torque arm? Hot Rod Works offers them, I believe....

    [​IMG]
     
  23. Bad Daddy
    Joined: Nov 13, 2010
    Posts: 829

    Bad Daddy
    Member

    Not sure if this helps, but this is how the old man set up the rear in the coupe. . .
     

    Attached Files:

  24. Rigid mounting the bones at the rear, like they did in the Iona pics, is no different than how common aftermarket (pete n jakes) ladder bars work. And therefore not much different from how Henry engineered the original rear setups with torque tubes.

    They're not missing the boat...you're missing the point. Sorry to be blunt...but guys like Danny (hotrodpro) and the Iona boys are all over it and totally nailing it %100...without question.

    And seriously though...how nice is Danny's setup!?!?!? F'N awesome...looks like an original piece and lets you run open drive. Genius...will be copying in the future!!!!
    -Steve
     
  25. V4F
    Joined: Aug 8, 2008
    Posts: 4,382

    V4F
    Member
    from middle ca.

    i dont have a sbc , but i do have a hopped banger / 5 speed . im going to build new arms , but im going to heim joint both ends & use better material , as molly tubing . under power on a rough road my rear end jumps . i know stay off rough roads . steve
     
  26. V4F
    Joined: Aug 8, 2008
    Posts: 4,382

    V4F
    Member
    from middle ca.

    how nice is Danny's setup

    which one is his ????????? .. steve
     
  27. plym49
    Joined: Aug 9, 2008
    Posts: 2,802

    plym49
    Member
    from Earth

    Not so fast. The setup in question is NOT 'just like Henry's' and it is 100% -- wrong.

    Ford had a closed drive line and the center of connection was exactly in line with the drive line. It was a perfect triangle and the rear could articulate (one wheel up and the other down) with no interference movement at all, because the pivots formed a perfect triangle.

    As soon as you move to an open drive line, you lose the triangle and the best you can do is approximate a triangle with a trapezoid. Look closely at the front end where the two tie rod ends are located. When the rear articulates, even though each ball can twist a little, the arms will twist. They HAVE to. They have no choice.

    On a dragster or Bonneville car, this is not a problem as the suspension rarely articulates.

    On a street car with extremely limited suspension travel, the problem becomes more pronounced.

    On a full street car, like a shoe box, you are asking for trouble if you design a suspension that depends on a flexing of the arms or axle to accommodate the interference movement induced by articulation.

    It does not matter that a lot of cars are built this way, or that a lot of aftermarket firms sell them that way. Wrong is wrong, geometry is geometry, and facts are facts.

    As you move the nose of that trapezoid closer together, and more in line with the longitudinal axis of the tail shaft, you can minimize the interference. Likewise by making the base of the trapezoid as wide as possible.

    But the finishing touch demands a front-end connection that can accomodate the interference movement without flexing the arms or axle. Tie rod ends are not the solution. Neither are Heim joints. Or hard polyurethane bushings. What you need is a soft rubber bushing (soft in yaw) or one of the fancy joints the hard core off-road people use. (In a off-road machine, articulation is all-important, so the off-road after market industry has developed some clever joints that can articulate as described. However, they are probably too large and heavy and expensive to be used on a street machine).
     
  28. V4F
    Joined: Aug 8, 2008
    Posts: 4,382

    V4F
    Member
    from middle ca.

    plym49
    do you have a pic or drawing of what you mean ? thank you .. steve
     
  29. plym49
    Joined: Aug 9, 2008
    Posts: 2,802

    plym49
    Member
    from Earth

    I don't.

    But here is something you can try with a piece of paper (science class time!).

    Cut a long isosceles triangle (the two sides equal length and longer than the base).

    Hold the very tip on the tabletop with your finger tip. Now you can raise or lower the rear, or articulate it, and the triangle does not flex. This is how a closed drive line is set up - the front ball joint can handle up-and-down (jounce and rebound) and articulation completely in line with the axis of the driveshaft.

    Now, instead, cut a trapezoid. The top will be closer together and the base, the same width as the base on that triangle. Hold the top down on the tabletop with two fingertips - right at the tips. 'Work' the suspension as you did before. Now, you see that the trapezoid must deflect to accommodate articulation. That's because the trapezoid cannot handle the interference motion. There is no interference motion with the triangle.

    As soon as you go to an open drive line with a transverse spring, the best you can do is to try to get your trapezoid to be as triangle-like as possible. That's why the common wisdom is to have the front as close together as possible and in line with the axis of the tranny's output shaft..

    The flaw is when you use a Heim joint or tie rod end. A Heim joint can only accept the tiniest of articulation. A tie rod end can accept a tiny bit more. After that, parts have to deflect to accommodate the articulation. A street vehicle sees a higher range of articulation than standard Heim joints or tie rod ends can handle

    The problem is avoided with semi-elliptic springs. Or a closed drive line. Or front bushings designed to accept the required amount of interference motion. Anything else is slim shady. The setup in question, regardless of the beauty of the welds, how long they have been in business, or how much the shop gets its back up with 'that's how we do it' rhetoric is slim shady.
     
    Last edited: Sep 6, 2011
  30. DICK SPADARO
    Joined: Jun 6, 2005
    Posts: 1,887

    DICK SPADARO
    Member Emeritus

    Now girls, no need to get in a wedgee pantie war. There is nothing wrong with the rigid mount rear and rotational mount front radius rod set up. While you are science class dissecting the torsional twist of the radius rod you forgot to figure in the fact that there is a pivot point at the front. In this design it is actually triangulated however the pivot point of triangulation is not at the convergence of the arms but at a point equidistant rearward. This actually allows the beam to have same degree of unencumbered torsional twist as a torque tube design pivot. The unit with the tie rod end provided a radial pivot for the arm as it moves in an arc is a good design. Looking at three axis, it locates the longitudinal position, triangulation locates the lateral position when combined with a panard rod and the ability to rotate about the locating mount just about cures the most severe torsional strain on a the control arm. The key is the ball pivot mount which allows more axial rotation than a hiem end or urethane mount. If you examined this under 6-8 " of delection bump you would see that there is minute amount of twist. Even a hiem end has 20-30 degrees rotation to eliminate the twist factor, the most ridgid of the 3 would be a urethane mount as it only allows for about 10 degrees of roll before it binds up.
     
    kidcampbell71 likes this.

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