HIGH SPEED WOBBLES on my F800 GS

Discussion in 'Parallel Universe' started by fractalsource, Jul 18, 2012.

  1. fractalsource

    fractalsource Adventurer

    Joined:
    Jul 9, 2012
    Oddometer:
    90
    Location:
    Idaho. USA
    At about 70 mph. or 112.65 kilometers per hour my bike began to feel wobbly on asphalt.
    I'm running new TKC 80's.
    I assumed it was the non-adjustable, upside-down forks and replacing them, - replacing the springs, and using heavier weight oil was an option for a remedy.
    - My local BMW dealer told me it was my tires. - I checked my tire pressure and wear.
    I adjusted my bike for my ride, using:
    http://www.photos4aidan.com/actions/F800GSPreload.html

    On the Interstate without wind or trucks to give me turbulence -
    Still, a wobble.

    So I bought a steering damper.
    Installed it.
    Adjusted it, as prescribed.
    Wobble gone.
    - Stabilized in Idaho.
    :rayof
    [​IMG]
    #1
  2. itsatdm

    itsatdm Long timer

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    There have been many complaints about the wobble. Most have been with tkc80 tires. At about 300 miles the wobble goes away. I initially jacked up the rear preload and dropped the forks 1/4" inch and the wobble went away.

    Since that time I have changed out the front springs and cartridge tube. I added a Hyperpro spring to rear and added some preload.

    It was a very good pavement bike. I have since added a Scotts stabilizer for off road. It made the bike feel like a heavier bike.

    All together, the thing is a rock. I do not care what tire is has on it, it goes where where you point it. The most stable bike I have ever owned.
    #2
  3. itsatdm

    itsatdm Long timer

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    Easy fix. Go ride in the dirt. Never wash it. :evil It must effect more than others, never bothered me.
    #3
  4. amackenzie

    amackenzie Adventurer

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    I run the TKC80s and I found airing up the tires helps, especially the front. I've never really had much of a problem with it though.

    If you're going to do a lot of high speed highway I'd keep them pretty hard.
    #4
  5. Snowy

    Snowy Long timer

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    Yep.

    Forks...shit. Options...shit. Solutions...like your link says:

    Things like this stopped me in my tracks. Then there were the failures that started to emerge with the kits.

    I have 2 motoX front ends awaiting that perfect moment where I have a surplus of time and money.

    Then the BMW front end goes the way of the Dodo.

    Front wheel clacking is most likely the disc pads floating in the caliper. Mine makes a hell of a noise. If you pull the front brake on and pump the forks see if it makes the noise then. It'll be the pads for sure.

    The wobbles - itsatdm has the way of it. It's a geometry thing most likely. Play with rear pre-load and front height. Raise the rear and drop the front each by 20mm and it changes everything about the way it behaves at freeway speeds.

    Some blame tyres, some blame pre-load...I just know this works after figuring it out on my own and then seeing that others agree.
    #5
  6. Dream Rider

    Dream Rider Servant

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    Location:
    Anywhere in the Northwest
    justbought 2012 f650gs. told dealer front wobbles then settles when i push left/right quick as inavoidance maneuver. usually above 65 mph. However, since the bike settles on its own that is "normal???" bike handles fine other wise. A little more shakey thatn my 1200 GSA behind semi's or in wind,but the bike is about 150 lbs lighter. Is this the same suspension as the 800 GS?
    #6
  7. fractalsource

    fractalsource Adventurer

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    I'm pretty sure you have adjustable front forks on the 2012 F650 GS.
    The F800 GS has upside down, non adjustable front forks. (What were they thinking?)

    I like the diagrams for adjusting a bikes suspension, on pages 12 and 13 of this pdf. from Ohlins.
    See: http://www.ohlins.com/Products/OwnersManuals/OM_07241-02.pdf

    Having said all that:
    I weigh too much for my suspension. (300+)
    So, I am getting an upgrade from:
    See: http://sasquatchrider.com/products.html

    My Scotts steering damper took out my high speed wobbles.
    That damper works really well. I like it very much.
    It does raise my bars. I can't use some wind screens, like the Windshield - VStream Touring Windshield - by ZTechnik without hitting my mirrors on the sides. Even with the mirror extenders. (I bought one and returned it.)
    See: http://www.ascycles.com/detail.aspx?ID=76186

    Now, I just have a bottoming out, issue. And a few noises I need to dampen.
    Someday, I will dial in, this bike. :jkam
    #7
  8. Kevfoley

    Kevfoley LocoRojo

    Joined:
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    Location:
    Cayman Islands

    I have the same problem on my F800 Trophy when running TKC80s, no problem when off road but a total pain when getting between places. Thanks for the solution.. looks like i need a damper..
    #8
  9. Full Power

    Full Power Long timer

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    Before you start throwing money at "Solutions", I recommend that you adjust the steering head bearing preload, according to factory specs.
    You may actually have a well designed, stable motorcycle, already in possession...... with loose bearings.
    #9
  10. chris73

    chris73 Been here awhile

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    Can you post a link for the method of doing this? Mine does this as well
    #10
  11. itsatdm

    itsatdm Long timer

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    Stock suspension and what do you weigh?. My now 5yr F800gs would get the weave on a new TKC80. My bike did not have a loose steering head nut.

    The unladen bike has more weight on the rear than the front and my theory is, it does not take much to start the weave on a set of new soft knobbys.

    See if this has any impact. Scrunch up as close as you can to the faux tank. If moving your body weight forward improves things, you can either jack up rear preload substantially or raise the forks about 10mm below the line inscribed on the forks.

    Even after I re sprung my bike, I still run the forks up a bit. Dirt or pavement it just goes where I point it.

    Stabilizers are nice too, I crank mine down on soft terrain or rocks.
    #11
  12. Full Power

    Full Power Long timer

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    Head Bearing preload is set thus:
    Remove handlebar clamp bolts, lift and secure handlebars, for clearance.
    Loosen (4) upper fork pinch bolts.
    Remove decorative BMW logo from 10mm hex steering stem bolt
    Tighten to 25nm
    Turn steering 3 times lock to lock.

    Loosen 60 degrees
    retorque to 11nm.
    Tighten fork pinch bolts to 19nm
    replace handlebars, tighten front bolts first, rear bolts last
    #12
  13. Kevfoley

    Kevfoley LocoRojo

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    interesting, worth checking the various options, weighing in at 74kg (163 lbs),

    It started on Motorways when travelling with loaded bike, increasing the preload on the rear suspension did help, but ultimately it did not fix the issue, same goes for tire pressures, increasing the air in the front tyre would increase stability up to a point but not eliminate the wobble, which when travelling at speed can get a little hairy!

    Will check the bearings, and see, but it does not seem loose.
    Scrubbed in TKC's or brand new dont seem to make much difference, just a but less bumpy on old ones ;)
    #13
  14. Snowy

    Snowy Long timer

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    On third set of steering head bearings.

    Steering damper.

    RMZ front end.

    They last longer now with the RMZ front end than before. But I need more kms on it before that is "factual". If I can get double the kms then I'll blame it on the standard front end.

    I don't suffer as many rim dings now, I've noticed. I'm much nastier to it than I used to be.
    #14
  15. Ceri JC

    Ceri JC UK GSer

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    I also have this on TKCs on my F800GS. Fitting a Rallemoto (RM2) steering dampener and setting it accordingly, means that it doesn't become a problem until about 100mph unladen and 90mph fully laden.
    #15
  16. too old for dirt

    too old for dirt Been here awhile

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    Had some minor head shake/vibration at speed and do not know what caused it. Adding preload cured it, but I like a softer suspension on the rear. Added a GPR stabilizer and the bike feels much better and I can run less preload on the rear.:clap
    #16
  17. Snowy

    Snowy Long timer

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    I thought for a long while that lowering the front end fixed this...or stiffening the rear. With the standard front end it definitely seemed to.

    But my RMZ front end is 40mm taller, with the same axle offset and basic measurements in fork centres to steering bearing etc.

    No wobbles. Even with the steering damper turned right down.

    Effectively I have increased rake and trail slightly.
    #17
  18. adkfreeridex

    adkfreeridex Adventurer

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    My 2012 would wobble at speeds greater than 80 mph, so I always cruise at 70. Last Wednesday i got the wobbles so bad that It made me crash. I don't remember it, but witnesses say I wobbled hard then went down. Had a TKC 80 on the front.

    I love my bike and am not going to give up on riding, but I need to know this wont happen again. I will go through and install a new rear spring, as the bike sit lower than most F8s because I think the previous owner really gave it a work out. Check head bearings. I'll look into lowering the front end and put a damper on it. Im going to have woodies build me a new front wheel. What are some more stable front tires that are still decently capable of road. Is there anything else I can do to enhance stability?
    #18
  19. RobbieO

    RobbieO Muskokatard

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    I had the same problem when I tried a TKC-80 too!

    Took the tire off and installed another brand, wobble gone!
    #19
  20. B_C_Ries

    B_C_Ries Long timer

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    The TKC-80 front seems taller than some other front tires, I think that may effect geometry, I Crank up rear preload when I mount my TKC-80's and back it off with other tires. I've noticed that if I am riding and I get wobbles with TKC-80's laying down on the tank (or whatever you call the stuff where other motorcycles have a tank) makes the wobbles go away.
    #20