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Thread: Gear tracking

  1. #1
    Redbaron180's Avatar
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    Gear tracking

    Some time back I installed Airframes 3 inch extended HD gear, and I have been trying to ignore the fact that it is out of track. It handles fine but yesterday I noticed one of my tires is showing some cord, so before I order up new skins I want to get it right. The Question for you wizards is can I bend those cold or should I heat them up? Thanks in advance.............

  2. #2
    mike mcs repair's Avatar
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    some hits....

    http://www.supercub.org/phpbb2/viewt...racking+adjust

    http://www.supercub.org/phpbb2/viewt...&highlight=bar


    wow ruff week on stars... pitchman billy mays dead too..... one bump on your head and....

  3. #3
    Steve Pierce's Avatar
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    There are issues with mixing and matching certain gear legs with other vendors cabane and lower gear. Vicki at Tamarack in Fairbanks and Steve at Atlees can tell you the combination and fix without having to bend something.
    Steve Pierce

    Everybody is ignorant, only on different subjects.
    Will Rogers

  4. #4
    RedEye's Avatar
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    My guess is the fuselage is out of whack not the gear.

  5. #5
    Redbaron180's Avatar
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    RedEye,
    there is little doubt that the fuselage is out, but it would seem that it would be eiser to adjust the gear than anything else. It flies streight so it doesn't matter to me if it is bent, I just want it to track streight.......

  6. #6
    RedEye's Avatar
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    My 3" gear from Airframes is mounted on my Airframes Inc fuselage. It is towed in just a bit. No visible tire wear, but when pulling it in the hanger it does pull the gear apart a little.

    I would tweak the gear to save the tires n not worry about the fuselage also.

  7. #7
    Redbaron180's Avatar
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    So back to the original question, cold or hot. Someone must know the best way. It looks pretty strong, seems like it might need heat. But then I'll have to repaint, so I was in hopes I could do it cold..........

  8. #8
    Redbaron180's Avatar
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    This morning I went out to the hangar, got out the strings, levels and laser to determine just what I had for track. It turns out that each wheel is towed in 18 inches measured 52 feet in front of the axle in the three point. That looks to be about 1 degree. Not as bad as I thought, but maybe a little excessive.................

  9. #9
    Steve Pierce's Avatar
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    I think 1 degree is good.
    Steve Pierce

    Everybody is ignorant, only on different subjects.
    Will Rogers

  10. #10

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    We found that simply measuring the tire grooves front and back was enough. If they were off by, say, an eighth of an inch you probably wouldn't notice. On airplanes where the difference was 3/4" we could detect slight problems in ground handling at higher speeds. One Stinson was almost unmanageable, and you know how stable the Stinson is!

  11. #11
    Redbaron180's Avatar
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    I can't imagine getting an accurate measurement from the tire, tires are all over the place. I used the brake disk, and that could be suspect. It depends how large of a tire you have but if you can measure 3/4 of an inch on a 6:00 it might be several degrees out, assuming the tire is symmetrical. My 1 degree each side is looking pretty good.................

  12. #12
    mike mcs repair's Avatar
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    for making the cessna shims shown in the video below i have learned: the brake disc is usually the best true surface because it fits in a machined recess in wheel.. but could be warped from use, but you would notice that in pulsing brake pedal....

    but easy to check... just jack up and "track" it by spinning it with an object close by to see if it wobbles...

    I also use the outside of rims, but they are all over the place and not a true machined surface so do the test as above....

    i was gonna post the measurement for a degree change.. but will have to reboot.......

  13. #13
    mike mcs repair's Avatar
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    so couple of examples, if the two points you measure on wheel/disc are:

    5.85" apart
    then the change is 1.22 degrees per 1/8" difference in measurement(2.45 degrees for 1/4" etc.)(forward minus rear measurement or whichever)

    or

    7.10" apart
    then the change is 1.05 degrees per 1/8" difference in measurement(2.10 degrees for 1/4"etc.)

    or so the CAD program said.......

    also a VERY important thing is the strait edge you put in front of gear to put carpenters square against, does not necessarily rest against both tires.... (if one gear is trailing for example the plane will track to the trailing gear side... if strait edge you measure from is just put against tires)

    the strait edge needs to be lined up to center of plane.. ie measure back to tail spring bolt from a point equal distance from center of strait edge by droping plum bob from plane cent between gear....

    did that make sense?

  14. #14

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    Yes. Eliminate parallax. We went for the simple measurement, but of course double checked it at several spots. If your tires themselves are off so much that you cannot measure to the nearest 1/8", then you have problems unrelated to the aircraft. Same with wheels.

    One guy built an incredible rig, including big pieces of steel, laser pointers, the tailwheel, and on and on. You can get all carried away, but the bottom line is - a teeny bit off will simply not affect you - if you can measure it on the tire, front to back, given several tries to average out the parallax, using a simple tape measure, you will know.

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