Front fork spring question
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Thread: Front fork spring question

  1. #1
    Junior Member marovn's Avatar
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    Front fork spring question

    I was thinking about adding a spacer under the spring retaining nut in my 73 cb450 in hope of stiffening them up by adding a little preload. Any thoughts or opinions out there? Thanks

  2. #2
    Super Moderator outobie's Avatar
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    Oil weights effect damping very different than preload.

    the objective starting g point for preload and spring weight selection is achieve about 20% static sag with the bike fully loaded

    it takes 3 people to set up suspension sag

    the rider in full gear
    one person to balance and steady the bike with the rider on in riding position
    one person to take and record suspension compression measurements

    when corrected for stiction, a bike with 5" of total travel should be set to 1" of sag fully loaded
    im me if interested in the full procedure
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  3. #3
    Senior Member Old Putz's Avatar
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    Preloading a spring doesn't stiffen it- it just raises the bike up on the suspension by whatever amount of preload you add.

    If you're having problems with the suspension bottoming out, you may want to go to stiffer springs. If half the bike's static sag (see outobie's note above) is taken up by just your weight on the bike, you may need to. Preload is great for fine-tuning ride height, but first you need to establish your static sag and use that as a starting point.
    Yeah, I've been doing this for a while...

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  5. #4
    Senior Member WintrSol's Avatar
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    Reducing the air volume above the oil effectively increases the spring stiffness, up to a point; adding fork oil, a small amount to each in equal measure, may achieve your desired results.
    Rick

    Mine is a mostly 1970 CB450K3

  6. #5
    Junior Member marovn's Avatar
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    Thanks guys, I'll recruit some help and check the sag. I have a feeling new springs may be the answer but i'll see if cleaning, oil change and seals make things better.

  7. #6
    Senior Member WintrSol's Avatar
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    Quote Originally Posted by marovn View Post
    Thanks guys, I'll recruit some help and check the sag. I have a feeling new springs may be the answer but i'll see if cleaning, oil change and seals make things better.
    If you remove the gaiters (assuming you have them), you can use a small tie-wrap. Lift the bike, put the tie-wrap on so it is snug, but not overly tight, lower the bike and sit on it.While balancing in your normal riding position, lift both feet briefly; I would hold the front brake on for stability. Then, lift the bike and measure how much the tie-wrap moved. It doesn't take three people to test sag, if you do it this way.
    Lefty likes this.
    Rick

    Mine is a mostly 1970 CB450K3

  8. #7
    Junior Member marovn's Avatar
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    Thanks Wintr, great suggestion. I'll get next to something to help balance and I should be able check the sag without help.

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