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Thread: tail spring re-arch

  1. #1
    rdooley79's Avatar
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    Default tail spring re-arch

    I've got a shimmy that was there with my old hard Maule tail wheel. Just replaced with the 8" wide matco single arm and it's a major improvement. Still shimmies though. I've got the dampening springs and the chains aren't tight or loose. I think it's caused by the spring flattening out.
    I'm running two leaves and want to get them re-arched the same.

    How would a guy re-arch the springs?
    Kitfox IV - 1200 (1994) #1830
    Rotax 912
    Grove Gear, Wheels, Brakes
    22" Desser Tundra Tires

  2. #2
    Super Moderator Av8r3400's Avatar
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    Default Re: tail spring re-arch

    Use a press to re-arch them.

    I am lucky to have a spring shop in my town. They do it for a couple bucks.
    Av8r3400
    Kitfox Model IV
    The Mangy Fox
    912UL 105hp Zipper
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  3. #3
    rdooley79's Avatar
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    Default Re: tail spring re-arch

    I'm not so lucky....

    I was thinking of getting new springs made but a couple inches longer to extend the wheel out and provide a little more dampening. Has anyone done this or is it not a good idea?

    What about using a thicker single piece of spring steel rather than two thinner ones? Or alternately four thinner pieces sandwiched together with the total thickness the same as stock?

    Just curious, I'd just like to find a press to re-arch my springs with for now and go fly!
    Kitfox IV - 1200 (1994) #1830
    Rotax 912
    Grove Gear, Wheels, Brakes
    22" Desser Tundra Tires

  4. #4
    Senior Member cap01's Avatar
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    Default Re: tail spring re-arch

    Funny you should bring this up as I just rearced mine last week. The spring I have on mine isn't a kitfox spring , rather a three piece spring that was for a piper . It required rearcing when I first installed it and worked pretty good for several years until last summer when I developed a shimmy . I only had the shimmy landing on hard surface . I'd don't use had surface very often so it wasn't a urgent problem but this spring I decided I'd better address the issue .
    I have been able to use one of those bottle jack hydraulic presses to get the job done . I did have the foresight to trace the spring on paper so I have a referance . I would re arc one spring then match the other two springs to that he first one so they are all the same arc . Kind of a guess about how much to rearc until the spring is reinstalled and the weight of the plane is back on the tailwheel . Since I've rearced mine I've made several landings on hard surface with no problems .
    chuck
    kitfox IV 1050
    912ul warpdrive
    flying B , yelm, wa

  5. #5
    Senior Member jrevens's Avatar
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    Default Re: tail spring re-arch

    Quote Originally Posted by rdooley79 View Post
    I'm not so lucky....

    I was thinking of getting new springs made but a couple inches longer to extend the wheel out and provide a little more dampening. Has anyone done this or is it not a good idea?

    What about using a thicker single piece of spring steel rather than two thinner ones? Or alternately four thinner pieces sandwiched together with the total thickness the same as stock?

    Just curious, I'd just like to find a press to re-arch my springs with for now and go fly!
    Hi Rhett,
    A couple of thoughts - as far as extending the spring length, a lot depends on the spring rate of the assembly itself - material, length, thickness, temper, etc., but I think you can run the risk of adding extra force & stress at the fuselage attach points because of the additional leverage. IMO, a thicker solid single leaf might not be good. Ideally with a tail spring, you want to match the spring rate of the main gear as close as possible - this can potentially improve 3 point landings. I've been intrigued with the solid rod (Whitman style) tailsprings, and curious if Lowell (Highwing) had any luck with his... maybe he will chime in.
    John Evens
    Arvada, CO
    Kitfox SS7 N27JE
    EAA Lifetime
    Chap. 43 honorary Lifetime

  6. #6
    Senior Member HighWing's Avatar
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    Default Re: tail spring re-arch

    Quote Originally Posted by jrevens View Post
    I've been intrigued with the solid rod (Whitman style) tailsprings, and curious if Lowell (Highwing) had any luck with his... maybe he will chime in.
    John,
    Interesting that you ask. I guess the best answer would be what kind of luck are you referring to. The real answer is that there were issues I was not able to address. When making the receiver for the spring, I could ream to precise internal dimension, but there is nothing out there spring wise that is dimensioned quite so accurately. I found that anything ordered would be guaranteed to be within a certain tolerance and my machine tools were not able to make things work.

    I was chatting with this guy, but nothing really hit home.
    http://www.irondesign-airparts.com/f...eel%20page.pdf
    Lowell Fitt
    Goodyear, AZ


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  7. #7
    Senior Member Dusty's Avatar
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    Default Re: tail spring re-arch

    We have found over here one of the best tail spring arching tools is a log splitter
    I have a grove? alloy tail spring which has no give.It has to go ,I have to hold the tail up in the rough,sooner or later it will end in tears!
    A slightly longer three leaf would bo a good idea

  8. #8
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    Default Re: tail spring re-arch

    Chuck -

    Can you describe how you rearced your spring with a bottle jack? Did
    you make some sort of fixture for doing it? I want to rework mine, and
    while the spring shop isn't very expensive ... I figure if I can do it myself
    for free that's even better.

    Thanks,
    Jeff

    Quote Originally Posted by cap01 View Post
    Funny you should bring this up as I just rearced mine last week. The spring I have on mine isn't a kitfox spring , rather a three piece spring that was for a piper . It required rearcing when I first installed it and worked pretty good for several years until last summer when I developed a shimmy . I only had the shimmy landing on hard surface . I'd don't use had surface very often so it wasn't a urgent problem but this spring I decided I'd better address the issue .
    I have been able to use one of those bottle jack hydraulic presses to get the job done . I did have the foresight to trace the spring on paper so I have a referance . I would re arc one spring then match the other two springs to that he first one so they are all the same arc . Kind of a guess about how much to rearc until the spring is reinstalled and the weight of the plane is back on the tailwheel . Since I've rearced mine I've made several landings on hard surface with no problems .

  9. #9
    Senior Member
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    Default Re: tail spring re-arch

    I think he was referring to a press that uses a bottle jack for the power source. I have a 20 ton press like this from Harbor Freight, and have used it to rearch tail springs. Works great. Jim Chuk

  10. #10
    Senior Member jiott's Avatar
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    Default Re: tail spring re-arch

    So apparently you guys just overbend the spring in a press until it takes a permanent set at the new arch. Do you not heat first and then heat again after and quench, etc.? I didn't know you could cold bend them to a new shape without damage.
    Jim Ott
    Portland, OR
    Kitfox SS7 flying
    Rotax 912ULS

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