Universal, one-size-fits-all penny-tech rear axle alignment tool

Discussion in 'Thumpers' started by creeper, Aug 24, 2006.

  1. creeper

    creeper Still alive...

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    So while I was finishing up the brake DIY guide it dawned on me that although I’ve referred to a rear axle alignment gauge, I’ve never gone into much detail on how it works, how to make one or what it looks like… and I’ve never shown a photo of one.

    OK... so it's not universal. The rod length will vary from bike to bike and it's of no value on a bike with snail cam adjusters like a DRZ for example... or a shaft drive anything. So I lied... so sue me. :deal


    What you need:
    All you need to make one is a 35 cent piece of steel 1/8” welding rod... about 36" worth, and a zip-tie. For a total investment of what? 40 cents maybe. You can make this tool tricker and fancier... but I doubt you can make it cheaper.
    Get at least 1/8" steel rod for this... smaller diameter or softer materials are too flexy and inaccurate.


    Why you need it:
    Rear axle alignment, with few exceptions, is usually only as accurate as the axle block and swingarm hash marks… which is to say not very accurate at all.
    Rear axle misalignment can cause unstable tracking down a straight road, “odd” handling in corners, accelerated tire wear, brake pad wear and chain and sprocket wear.


    How you make it:
    Cut the rod to length so it is a few inches longer than the approximate distance from your swingarm pivot shaft center to the rear axle center… in the case of the KTM LC4, about 29-30” is fine.

    [​IMG]

    Grind a point on one end of the rod and bend that end at a 90 degree angle. The length of this bend will vary from brand to brand, model to model, but the idea is to have the major length of rod parallel with the swingarm when measuring.
    In the case of the KTM LC4, a handy length is about ¾”.

    Now grab a zip tie, put it tight over the long end of the rod and cut the tail off short and to a point. Congrats… you have made a tool.

    [​IMG]

    If you need to, you can make more complicated sets of bends to clear things that are permanently in the way. The drawing is an approximation of a tool for a '79 to present Harley-Davidson with a rubber mount driveline.

    [​IMG]

    How it works:
    On a KTM LC4, there are rounded plastic buttons in both ends of the swingarm pivot shaft and one on the fixed end of the rear axle… and then an aluminum axle nut.

    It doesn’t matter which side you start on. You place the pointy end in the center of the plastic button on the swingarm pivot shaft...

    [​IMG]

    ... and slide the zip-tie so the pointy end of it aligns with the center of the axle… that is the "reference length" for one side.

    [​IMG]

    Now you transfer the tool to the other side and see where the center of the axle is in relationship to the reference length.

    [​IMG]

    Adjust that side of the axle (or both sides, more or less) until both sides measure the same distance by the tool, then using the current alignment as a baseline, readjust your axle for proper chain tension for your particular bike.
    That's it... you done. :clap


    This is the "whole tool"... complete with blatant promotional background. :evil

    [​IMG]


    Small example of why alignment is a good thing:
    It’s hard to believe, but with a 40 cent tool, you can get your axle aligned to an accuracy of less than one millimeter.
    Can you screw it up? Sure you can... I did once recently because I wasn't paying attention, and my rear brake pads looked like this with a less than 2mm misalignment:

    [​IMG]

    So there ya go,
    C
    #1
  2. MF1A

    MF1A Ride with the Wind

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    Hey Creeper , great info thanks dude :freaky
    #2
  3. Odysseus

    Odysseus Stoic Philosopher

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    Yesterday we get an awesome DIY brake guide, and now today this!! Creeper you are truely a gentlemen mechanic, thank you again.
    #3
  4. creeper

    creeper Still alive...

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    One kinda fell in line with the other... this took about an hour and half to do, so no biggie.

    Hope it comes in handy. :D
    #4
  5. tedder

    tedder irregular

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    That is kinda cool.

    I use the Motion Pro chain guide- it's something like $20, easy to use on any bike (even the DRZ).
    #5
  6. meat popsicle

    meat popsicle Ignostic

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    What TDC-C is to valve adjustments, rear axle alignment is to drivetrain adjustment. (cut me some slack, it's not perfect)

    Dotting all yer i's and crossing all yer t's - good man.

    I will have to mate this with your brake DIY thread, since I note you snuck most of the adjustment method in a post about your tool. No wait, that came out wrong... :arg
    #6
  7. creeper

    creeper Still alive...

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    Your thinking of Colin...
    #7
  8. meat popsicle

    meat popsicle Ignostic

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    Freudian slip? Oopsie...
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  9. RMac

    RMac Cheese!

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    Thanks Creeper. I've seen other methods but this is elegant and best of all, cheap.
    Ditto for the brake guide too.
    #9
  10. creeper

    creeper Still alive...

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    Hear that Meat? I'm fuckin' elegant. So I gotcher Freudian slip right here buddy. :ksteve
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  11. slideways

    slideways permanent ex-pat

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    That deserves a cool tool award.
    #11
  12. KenR

    KenR Long timer

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    Excellent!

    BTW, that tool will also work real well for measuring suspension sag on the bike without fussing with a tape measure every time. Just use a Sharpie to mark the rod in 1/2" increments and you've got a quick way to measure the effect of your spring preload adjustments.
    #12
  13. DaFoole

    DaFoole Erudite inchoate...

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    Thanks Creep!!:clap Great idea even I can build....:lol3 Ummm...why can't you use it on a "snail-cam" bike??? Aren't the reference points the same???:ear
    #13
  14. creeper

    creeper Still alive...

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    You can use it on a snail cam axle, but you really can't do anything about it if it's misaligned.
    I imagine there are a few ways you could even align it... one that comes to mind off the bat is to grind down the register pin a bit on the swingarm on the "long side" to even things up. :dunno
    If that worked, and assuming the snail cams match, that would be the first and last time you'd need the gauge. :lol3
    #14
  15. creeper

    creeper Still alive...

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    Yep... or a few more zipties. One for wheel off, one for static and one for rider weight. Hell, a few more just for fun... maybe in colors. :lol3

    Colors... huh, that's not such a goofy idea. :scratch
    #15
  16. meat popsicle

    meat popsicle Ignostic

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    You did that on purpose :rolleyes
    (you can't use fuckin' and elegant side by side... :rofl)
    #16
  17. dagwood

    dagwood Banned

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    :lol3
    you've got way Way to much time on your hands
    :augie
    :zilla
    #17
  18. creeper

    creeper Still alive...

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    You'd like to think that, wouldn't cha. :D
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  19. creeper

    creeper Still alive...

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    Sure I can... you did. :evil
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  20. dagwood

    dagwood Banned

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    :huh

    the hell you can't.
    "she looked fuckin Elegant bent over the back of my KTM"

    See. Done...:deal
    #20