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Loose rear end

Discussion in 'Mechanics Garage' started by baartmjf, Apr 9, 2012.

  1. baartmjf

    baartmjf New Member

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    I have a 2009 VFR800 and I am experiencing a sort of a bouncing swing in the rear end of my bike when I go through corners. When i have a pillion on the back it reduces the effect but it is still there. Any idea what could cause that?
     


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  2. Rainbow7

    Rainbow7 New Member

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    You need to adjust your preload.
     


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  3. Meatloaf

    Meatloaf New Member

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    You also should increase your rebound adjustment on your rear shock. How much do you weigh? What setting is your preload for your rear shock.

    Just an FYI, make small adjustments to your rebound as a tiny bit can make a huge difference.
     


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  4. baartmjf

    baartmjf New Member

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    Must the preload be softer or harder?
     


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  5. baartmjf

    baartmjf New Member

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    I have tried to increase the rebound but it didnt do much. If you say I must make small adjustments is that like a 1/4 turn at a time? I weigh 100kg. Can it be that my preload is to soft? I never had this problem and I was thinking that maybe the spring needs a bit more tention now.
     


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  6. Rainbow7

    Rainbow7 New Member

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    Firmer, if you're experiencing wallowing.
     


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  7. baartmjf

    baartmjf New Member

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    Thanx I'm going to try that.
     


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  8. kennybobby

    kennybobby New Member

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    Heart of Dixie Georgia Boys mighta been usin' dat
    Has it been dropped? Are the wheels aligned? What is the condition of the tires--are they rounded over from riding corners or worn in the middle with a squared off profile from riding interstate roads? Squared off tires definitely cause wallowing in corners.

    Wallow is a low-frequency instability. If it's not the tires then i would think adding more damping on both compression and rebound would be needed to solve the issue. Increasing stiffness/preload (or adding a passenger) might change the frequency or amplitude but won't damp it out.

    To quickly find the best damping i like to go full range at first to see if it is in the right direction, then cut it in half to dial it in. e.g if it has ten turns adjustment go fully in or out, try it to see if better or worse. If worse go to the other end, but if better then cut it back 5 turns and test again. If worse then turn it in 2.5 turns, or if better then back it out 2.5. Test again and adjust +/- 1.25 turns. Test, adjust +/- .75 turns, etc...
     


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  9. Meatloaf

    Meatloaf New Member

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    A 1/4 turn is a quite a big adjustment, especially when you are getting close to your settings.

    You weigh almost the same as I do. I run with the preload on the 6th notch (one from max preload) and my rebound adjustment is set at about 1/4 turn from full hard.

    Kennybobby has a really good suggestion. Set the setting in one direction as far as it will go and see if it takes you in the direction you are wanting... then go full opposite just to see what you experience. Just be a little easy on the bike as it is probably going to react much differently than you would expect. Then you can start dialing things in the way you want them. It took me a good 3 months to get things where I wanted them once I got the bike. Small adjustments here and there made a huge difference and I would ride for a week or so in various conditions before I'd make a change.
     


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  10. DaHose

    DaHose New Member

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    I am about 115 kilo and my settings are the same as Meatloaf. Heavy rear preload and high damping make big boys happy.

    Jose
     


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  11. baartmjf

    baartmjf New Member

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    I replaced the tyre and had the wheel balanced. Didnt check the alignment. How is that done? I did increase the preloead but then it got worse but when I also made the rebound harder with the increased preload it improved a lot. It was so bad that I couldnt corner at 120 kph but after the adjustment I felt comfortable at 180kph in corners. I will still have to do a bit of adjustment to get it to 100%. Thank you for the advise.
     


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  12. baartmjf

    baartmjf New Member

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    My preload is at the 4th notch now where it used to be on the third and my rebound is at a full turn out. Im going to increase the reboung a bit more to see what happens. With these settings my bike is a lot more stable though nor 100% yet. Above 180kph i still get some swinging.
     


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