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Thread: Fork springs, tight coils up or down? Thanks.

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    Fork springs, tight coils up or down? Thanks.

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    Administrator 20774's Avatar
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    From some notes by Tom Cutter, the tighter-wound end goes up, because it is the sprung end, and you always want to keep unsprung weight to a minimum. But given the relative weights of things, it probably doesn't make that much difference.
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    If the closer coils are softer I think that they should go in first. The reason is the rest of the spring would remain relatively sill in the tube as the close coils compress and expand.

    If the close coils are softer and placed at the top of the tube the entire spring would have to move back and forth before the softer close coils compress.

    Maybe I should put on my tinfoil hat.

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    Unfunded content provider tommcgee's Avatar
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    One reason why I like straight rate springs over progressive rate...
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    Enjoy The Ride saddleman's Avatar
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    On springs that have coils closer to each other on one end that end should always go to the end that does not move. On forks or shocks it would go on the top side. On a valve spring in a cylinder head it would go against the head.
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    Aspiring Profligate jeff488's Avatar
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    Quote Originally Posted by saddleman View Post
    On springs that have coils closer to each other on one end that end should always go to the end that does not move..
    Can you explain why, please?
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    Registered User dmftoy1's Avatar
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    I can't answer bikes, but on jeeps it goes that way. The way it was explained to me is that the lower portion compresses first and more easily. . . Could be bunk as I'm not a spring scientist but it's DEFINATELY how they tell you to do it on lift kits

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    Small road corner junkie pffog's Avatar
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    Quote Originally Posted by jeff488 View Post
    Can you explain why, please?
    The unsprung weight comment partly explains it. But basically the tighter coils are denser, thus have more mass to move, plus more inertia on rebound. The KISS answer, would you rather quickly pick up a bowling ball or a tennis ball, and which one could you do so without moving the rest of your body and not just your arm.
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    Aspiring Profligate jeff488's Avatar
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    Quote Originally Posted by r80andr100rt View Post
    If the closer coils are softer I think that they should go in first. The reason is the rest of the spring would remain relatively sill in the tube as the close coils compress and expand.

    If the close coils are softer and placed at the top of the tube the entire spring would have to move back and forth before the softer close coils compress.

    Maybe I should put on my tinfoil hat.
    I always thought that the closer ones are softer, too.
    It doesn't seem to me that unsprung weight is a critical factor in a vehicle as agricultural as an airhead,
    and also seems to me that one would want the soft part of the spring to be affected first by the compression. I'm no engineer. Just curious.

    I don't know about how lift kits affect suspension geometry, and how the supposed use of the lifted vehicle makes a difference, but it seems that there would be factors between the two types of vehicle that make a comparison an iffy proposition.
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    Small road corner junkie pffog's Avatar
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    Quote Originally Posted by jeff488 View Post
    .........................
    and also seems to me that one would want the soft part of the spring to be affected first by the compression. I'm no engineer. Just curious................
    The soft part of the spring IS effected first, regardless of its position in the spring. Remember the basics, every action has an equal and opposite reaction. a spring is just a long torsion rod, that is coiled, so the compression really imparts a twisting force in the cross section. If the soft end is at the top, it ill still be compressed first, regardless of which end is moved, because the reaction is the mass and gravity pushing on the top.
    2010 F800GS Full Ohlins package, '04 R1100S Replika
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    Aspiring Profligate jeff488's Avatar
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    So, then the only reason to put the closer wound coils at the top is to reduce unsprung weight?
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    I put the tighter wound coils on top because that is what the manufacturer (Wilbers) recommended for my F800GS. Can't see an appreciable difference between airhead and F suspensions in that regard.
    I figure Wilbers knows suspension much better than I, so their recommendation is sufficient.

    it's sort of like asking "how does counter-steering work?" Who the hell cares? Just knowing that it does is sufficient, and my knowing/not knowing changes nothing in the application of the technique.
    Ride Safe, Ride Lots

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    Aspiring Profligate jeff488's Avatar
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    I wasn't trying to be contentious, but just want to know why.

    Curiosity often leads me to ask why a thing should be done one way rather than another. That understanding, aside from satisfying the desire to know, can help do something in a better way.

    I was curious about counter-steering too, and having learned how it works, also learned to be a slightly better rider.
    '04 Silver R1150RT "Big Oel". '05 Yellow KLR 650
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    Registered User toooldtocare's Avatar
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    The last time I replaced a set of fork springs with progressive springs (95 R100RT in 1998) I remember putting the tighter coils up. I think it was because I would not have to recalculate how much fork oil to put back in since the coils did not displace anymore than the stock ones. That was my reasoning anyway, at the time.

    Wayne

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    Quote Originally Posted by jeff488 View Post
    I wasn't trying to be contentious, but just want to know why.

    Curiosity often leads me to ask why a thing should be done one way rather than another. That understanding, aside from satisfying the desire to know, can help do something in a better way.

    I was curious about counter-steering too, and having learned how it works, also learned to be a slightly better rider.
    I fully agree with the curiosity aspect, and that sometimes understanding how leads to a better overall comprehension of the subject.
    however, I would love to hear how your understanding the physics of exactly how counter-steering works translates into superior performance with its usage. much like other laws of physics, "how" is an esoteric realm, and matters naught in the functionality. to wit: we have only a rudimentary understanding of all the dynamics of gravity, especially as it relates to interplanetary objects, yet no one seems to have trouble operating under the premise that things fall down, not up.
    It is much the same with countersteering- the exactitude of "how" it works is relatively inconsequential when compared to the realization of how to make it happen. and THAT does not require any understanding of the dynamics of how.
    care to describe how it might have been different than that for you?

    (apologies for the mini-hijack, but the "coils up or down?" question seems to have been answered)
    Ride Safe, Ride Lots

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