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a different 3 link

Discussion in 'The Garage' started by randyb12, Oct 15, 2005.

  1. randyb12

    randyb12 Registered Member

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    I am considering a 3 link front setup, but with a twist:
    The center link will be a torque arm. Like a radius arm.
    The outer links will attach at the horizontal center line of the axle tube and angle in 12 degrees.
    The links will all attach to a crossmember on the same axis so that the pivot points are all on the same horizontal plane.
    The arms will be 42"' long.
    I will be useing a track bar as well. The track bar will be at the same angle as well as attach at the same points in relation to the drag link.
    The links are made of 2x2x0.25" tubing and the rod ends are from Suicide doors.
    http://www.suicidedoors.com/4Link_Parts_Square_4-Link_Bar_Bung_Kits.php#
    The Coil over shocks are Sway-a-way racerunners with dual rate springs.
    This is in a heavy truck that sees some hwy miles to and from the trails.
    So...
    I am trying to eliminate the twisting force caused by a standard 3 link when 1 tire has more traction than the other under heavy loads like a panic stop from 60mph on the hwy.. As well as reduce the stress on the links and brackets. I think that with the links all directly behind the axle tube the chance of a bracket failure is greatly reduced.
    In my case a standard 3 link with the center link on top won't work. It will have to be reversed so that the center link is on the bottom and the outer links are on top. To get the seperation I need with my 46" tall tires the top brackets would have to be 6" tall. If you think about it the brackets would have a treamendous amount of stress on them under braking.and the single bottom link would have the rotational force as well as the braking force on it.
    I just want it as safe as it can be.
    I think this setup will act like radius arms but still flex like a 3 link.
    What do you all think?
     
  2. BigOrange90Jimmy

    BigOrange90Jimmy 1/2 ton status Premium Member

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    You're going to have to run a trac bar, or panhard, whatever you want to call it. You will not be creating a triangulated geometry to keep the axle from shifting side-to-side. I would also want more than one "radius arm" to help with the rotational forces.

    In other words, just 4-link it and be done.
     
  3. Geargrinder

    Geargrinder 1/2 ton status

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    :rolleyes:
    I would buld that rad. REAL stout ;)
     
  4. randyb12

    randyb12 Registered Member

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    No room or I would have done that. Unless you like rock anchors on your rig.
     
  5. randyb12

    randyb12 Registered Member

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    Yeah, I know. This is stronger than a standard 3 link. Which relies on a single arm to keep the axle from rotating. The center link would have 2 2x2x0.25" arms that join at the chassis with a single rod end. Their would be 9" of seperation at the axle end with 2 rod ends. Each with 1-1/8" shanks, actually all links will have these big rod ends.
    Any thoughts on how this would work compared to a standard radius arm or 3 link?
     
  6. BigOrange90Jimmy

    BigOrange90Jimmy 1/2 ton status Premium Member

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    Since when did a 4-link become a rock anchor? Doesn't seem to deter many custom buggies these days, and it sure isn't hurting the Jeep crowd.

    FWIW, if the links aren't hanging lower than the diff, they aren't rock anchors.
     
  7. sled_dog

    sled_dog 1 ton status

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    That was his point, he couldn't fit a convential setup without running links below the axle.

    Can you draw what you are saying? I read it a few times and still don't quite grasp the image.
     
  8. ryan22re

    ryan22re 1/2 ton status

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    i think he wants to build a suspension like the late model f-bodies have two links and a torque arm. with a panhard rod of course.

    it sounds like it should work, but i would recommed currie's johnny joint over whatever joints he was planning on using. (johnny joints are cheaper it seems and you can get them with the threaded rod of course.)

    it seems to me that in order to work properly the torque arm would have to be much longer than the other two links. if i remember correctly the length of the torque arm has alot to do with your instant center, and being too short could cause it to jack up in the front end under accel and squat real badly on decel. which may not be a bad thing.

    whats wrong with leaf springs anyway?

    ryan
     
  9. sled_dog

    sled_dog 1 ton status

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    you are quite right, a short torque arm would lead to scary characteristics which is exactly what he is trying to avoid.
     
  10. randyb12

    randyb12 Registered Member

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    Sorry, I am blind and have no way of doing that.
    picture a HP D60 with a ladder bar in the center of the axle and a control arm on each side of the axle by the spring perches. The outer links will be mounted so that they are even with the horizontal center line of the axle.--O the dashs are the link and the O is the axle.
    Does that help.

    As for a short torque arm, I did my homework and decided on a 42" long arm mounted to the trasmission crossmember. The crossmember will be reinforced with a piece of 3/8 bar stock 4" wide. the plate will be welded to the crossmember and bolted to the frame with the stock bolt plus 2 1/2" bolts for good measure.
     
  11. randyb12

    randyb12 Registered Member

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    All 3 links would have to be the same lenth or it would try to pull itself apart when it moves up and down.
    With 46" Baja Claws leafs kill your turning radius.
    And as memtioned above the torque arm will mount at the rear of the transmission.
     
  12. sled_dog

    sled_dog 1 ton status

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    should be interesting to say the least. I don't feel like drawing it out and thinking over the design, build it let us know how it works, ha.
     
  13. randyb12

    randyb12 Registered Member

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    thanks, wheres the tech?
     

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