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Technical The old beam axle shimmy at speed

Discussion in 'The Hokey Ass Message Board' started by 325w, Aug 15, 2020.

  1. Bought this car earlier this year. At 45 it started the shimmy. Toe in set front wheels balanced. It still shimmys. Has a Speedway front end under it. Swapped out the steering box for a borgeson. Shimmy didn't start till about 54. Much tighter and more response than the speedway box. Angle finder on the upper part of the axle beam. It shows about 6 degrees on both sides. Has hair pin radis rods. So how do I adjusts the hairpins. Thinking I want to lay it back a bit. On the 32 coupe I had it was four bar. Took both top bars off and adjusted the to cause the axle to lean back. So do I do the hair pins the same way?
     
  2. Fordors
    Joined: Sep 22, 2016
    Posts: 5,410

    Fordors
    Member

    EDE855D6-B944-407F-B7F2-8BE6C4B7AD46.jpeg

    Adjust your caster with the clevises, screw the top one in and the lower out, just be sure to leave an adequate amount of thread in the tube.
     
    AHotRod likes this.
  3. What condition are the king pins and bushings in?
     
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  4. fiftyv8
    Joined: Mar 11, 2007
    Posts: 5,394

    fiftyv8
    Member
    from CO & WA

    Also tie rod ends, check for wear...
    What angle are the front shackles on?
     

  5. All seems very tight
     
  6. fortynut
    Joined: Jul 16, 2008
    Posts: 1,038

    fortynut
    Member

    Tie rod ends? Not worn and no slop. How about the adjustment of the Panhard bar? It does have one, right? Also, available from some vendors is a shock absorber device that locates off the tie rod to stop shimmy. Originally used by VW, it aids in this very issue.
     
    hotrodjack33 and dana barlow like this.
  7. Has a panhard bar. What about the panhard adjustment. It appears to be evenly located.
    Should it be pushing one way are another
     
  8. 2OLD2FAST
    Joined: Feb 3, 2010
    Posts: 5,262

    2OLD2FAST
    Member
    from illinois

    Buy a steering damper . Install the steering damper . Enjoy driving your car ! Or ......drive yourself insane spending a bunch of time and money to TRY and solve a problem that may not be solvable ! BTDT
     
    Last edited: Aug 15, 2020
  9. Mimilan
    Joined: Jun 13, 2019
    Posts: 1,230

    Mimilan
    Member


    What is the caster?
    And what is the scrub radius?
    Too much caster can create lift on a lightweight vehicle [instead of self aligning the steering]


    This is usually triggered over a slightly uneven surface by too much scrub radius [caused by smaller overall diameter wheels / or wheels widened to much outwards]
     
    Last edited: Aug 15, 2020
    farmalldan likes this.
  10. fordflambe
    Joined: Apr 9, 2007
    Posts: 573

    fordflambe
    Member

    Before you go too far with the chassis, check your tires for out of round or separation.
     
    lothiandon1940 likes this.
  11. I always set the axle at 7 degrees, check all the tie rod ends and jack the front end up and see if you. HRPhave in play in the king pins/
     
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  12. hotrodjack33
    Joined: Aug 19, 2019
    Posts: 4,154

    hotrodjack33
    ALLIANCE MEMBER

    @2OLD2FAST is absolutely correct...buy a steering dampner.
    I spent over 10 years chasing the gremilins causing the wobble on my 32 Ford. Finally bought a SoCal steering stabilizer as a last resort and my problems were fixed ! If I had done that in the first place, I could have saved myself a lot of wasted $
     
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  13. hotrodjack33
    Joined: Aug 19, 2019
    Posts: 4,154

    hotrodjack33
    ALLIANCE MEMBER

  14. krylon32
    Joined: Jan 29, 2006
    Posts: 9,471

    krylon32
    ALLIANCE MEMBER
    from Nebraska
    1. Central Nebraska H.A.M.B.

    I have a steering damper on all 4 of my deuces and the 40 and they drive perfect.Some people think they are a crutch but I think they make a straight axle chassis more enjoyable. I started using them on my own cars about 15 years ago.
     
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  15. 2OLD2FAST
    Joined: Feb 3, 2010
    Posts: 5,262

    2OLD2FAST
    Member
    from illinois

    If you like to fab your own stuff , you can save a few bucks by ordering a VW beetle( mid 60's) steering damper ( just like the one shown) for around $20 ... Then fan your own brackets ..
     
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  16. bchctybob
    Joined: Sep 18, 2011
    Posts: 5,245

    bchctybob
    Member

    I’m a fan of using the steering damper too but you do need to look at all of the front end components and be sure there is no slop anywhere. Also some spindle, drum, wheel combinations make for a poor scrub radius which can make the front end more susceptible to shimmy. Can you post a few pictures?


    Sent from my iPad using The H.A.M.B. mobile app
     
    olscrounger likes this.
  17. While a steering damper may help I've never needed one if the front end components were in good condition...
     
  18. alchemy
    Joined: Sep 27, 2002
    Posts: 20,519

    alchemy
    Member

    Do you have heim ends on your tie rod? What is the toe-in set at? Show us some good clear pics of the components, and nice side and front shots so we can see the angles of stuff.
     
  19. Boneyard51
    Joined: Dec 10, 2017
    Posts: 6,451

    Boneyard51
    Member

    Increase or decrease your caster, a little at a time until the shimmy goes away. This is assuming, everything thing is tight and your wheel/ tires are round and balanced and your toe in is correct. “ Your” caster may have to be a little more or less than the other guy’s.








    Bones
     
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  20. Marty Strode
    Joined: Apr 28, 2011
    Posts: 8,910

    Marty Strode
    Member

    This, borrow another set of wheels and tires to try on the front, process of elimination.
     
  21. nutter_street_rodder
    Joined: Sep 16, 2011
    Posts: 102

    nutter_street_rodder
    Member
    from Nevis MN

    the "old way" of stopping it was to set the toe out 1/16".... and it is a patch for the real problem of something loose.
     
  22. Where exactly is this? A beam is not flat on top.
     
    Boneyard51 and gimpyshotrods like this.
  23. Dirty Dug
    Joined: Jan 11, 2003
    Posts: 3,712

    Dirty Dug
    Member

    What tire pressure are you running?
     
  24. 25 lbs tire pressure. Using an angle finder on the front of the axle vertically. The king pin top is not level enough to set the finder. Will have to ask Thomas what he set toe at.
     
  25. Dampner help a bunch. But it's not there yet.
     
    Boneyard51 likes this.
  26. sdluck
    Joined: Sep 19, 2006
    Posts: 3,193

    sdluck
    Member

    A socket or piece of pipe on the kingpin boss
     
  27. Why didn't I think of that.
    Moved one side to close to seven. Other side I could only get it to 9. That was using way of measure. It helped able to drive 60. Right side the bat wing is not straight with the hair pin. Will try again.
     
  28. made it to 70 very little shimmy. Panhard bar was ove tightened.Made right bat wing crooked. Broke it loose and you could feel the suspension relax.
    Thank you sdluck. Your idea was spot on! I owe ya!
    Thanks again
     
  29. sdluck
    Joined: Sep 19, 2006
    Posts: 3,193

    sdluck
    Member

    Glad I could help,as are all of us.
     
    kadillackid and X38 like this.
  30. To date I made 70 mph with only a little shimmy are vibration. New Borgeson steering box to replace the Speedway. New Borgeson steering column vibaration steering joint. A steering dampner also. Now to the rear and get the tires balance checked. Then replace the Speedway coil overs.
     

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