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Thread: Tail wheel shimmy

  1. #1

    Join Date
    Jun 2013
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    Default Tail wheel shimmy

    Ok guys- need some help here. There has been a a few landings now where it feels like I have a flat tire, just recently I figured out it was my tail wheel. I have a Matco single arm with the new KitFox triple spring and it only seems to happen on pavement. Is there something I should check on my tail wheel? The tire is a little worn- would that cause it? Any suggestions would be appreciated. I do prefer wheel landings vs. three point- maybe I'm doing something different

    Thanks,

    Scott

  2. #2
    GMKman's Avatar
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    Jul 2016
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    Default Re: Tail wheel shimmy

    Not sure if this the problem you're having but when I owned a Glastar tail dragger, the tail wheel would shimmy when the springs started to "sag" hence changing the caster angle of the swivel bearing. A wedge shim or re-arching the spring would fix it. That's assuming the bolts are tight and the bearings are not bad.
    I hope that helps.
    Brad.
    Last edited by GMKman; 08-14-2016 at 04:15 PM.

  3. #3
    dynomike's Avatar
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    Default Re: Tail wheel shimmy

    I battled a shimmy for a hundred hours in my avid ,I took only a quarter turn on the big nut to preload the joint .cant feel the pressure difference in the rudder pedals but no shimmy in three hundred more hours.

  4. #4
    Senior Member PapuaPilot's Avatar
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    Default Re: Tail wheel shimmy

    There has been a lot of discussion on this forum about tailwheel shimmy. If you search this you will find lots of ideas that will help you.
    Phil Nelson
    A&P-IA, Maintenance Instructor
    KF 5 Outback, Cont. IO-240
    Flying since 2016

  5. #5

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    Jan 2014
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    Australia
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    Default Re: Tail wheel shimmy

    Lots of good stuff can be found on this forum.
    My understanding is shimmy is usually
    1. Angle wrong (sometimes because leaf springs have sagged
    2. Lose chains

    Could the leaf spring be sagging changing the angle slightly and also loosening the chains?

    Jono

  6. #6
    Senior Member jiott's Avatar
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    Default Re: Tail wheel shimmy

    I had the shimmy problem, most likely due to sagging of the 3-leaf spring from rough dirt on/off airport strips. Tried tightening the big tailwheel nut and then the springs-helped a little but no real solution. Was going to have the leaf spring angle reset by a spring shop, but decided it would just happen again for the same reasons. I bit the bullet and installed the Grove solid aluminum spring and no shimmy ever since.
    Jim Ott
    Portland, OR
    Kitfox SS7 flying
    Rotax 912ULS

  7. #7

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    Default Re: Tail wheel shimmy

    Quote Originally Posted by PapuaPilot View Post
    There has been a lot of discussion on this forum about tailwheel shimmy. If you search this you will find lots of ideas that will help you.
    I always look first. 4 threads specific to tail wheel shimmy is not a lot- and every one said re arch the spring(mine have less than 50 hours on them)

    I have tightened the mount bolt, but I don't run my chains tight. The weird thing is it does not happen every time- that's why I was asking flying style?

    Thanks,

    Scott

  8. #8

    Join Date
    Sep 2009
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    coquille oregon
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    Default Re: Tail wheel shimmy

    What do you suspect was the solution?
    The rigidity or the angle of the tail wheel, or both when you went with the Grove tail spring?

  9. #9
    Senior Member PapuaPilot's Avatar
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    Default Re: Tail wheel shimmy

    I upgraded to the Grove single leaf and have not had a shimmy since. My shimmy happened when I was doing my gross weight/aft CG Phase 1 testing. The problem was the angle due to the heavier tail. I have not had a problem since.

    FYI when I experience the shimmy I learned to unload the tail by pushing forward on the stick or by doing wheel landings and holding the tail off as long as possible. Mine didn't do it every time either, it showed up when the chains were loose, aft CG and especially doing 3 point landings that were a little hard.
    Phil Nelson
    A&P-IA, Maintenance Instructor
    KF 5 Outback, Cont. IO-240
    Flying since 2016

  10. #10
    Senior Member jiott's Avatar
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    Default Re: Tail wheel shimmy

    My experience was somewhat similar to Phil's. I have the ABW tailwheel which is quite heavy. I really don't know for sure, but I suspect the success of the Grove is both things: stiffer so it doesn't sag so much, especially over time, and the angle is somewhat better.
    Jim Ott
    Portland, OR
    Kitfox SS7 flying
    Rotax 912ULS

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