Just finished adventure modding my F650GS and now it has a terrible steering wobble!

Discussion in 'Parallel Universe' started by Excite-Bike, Dec 26, 2014.

  1. Excite-Bike

    Excite-Bike Been here awhile

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    [​IMG]

    It's a standard height 2010 model and ran as smooth as a missile over 110mph when I first got it a month ago but now that I added everything below it's become frightening above 75mph.
    It had 4,500 miles on it when I got it and just clicked over 5k now.
    Here is a pic from the day I bought the bike

    It also has vibrations that have been causing my left hand to fall asleep too. That may have been present all along but took me a while to recognize because I thought it was my new tight un-broken-in gloves but it's clear now that it's from vibrations not the gloves.

    Mods:
    1. K&N Air Filter
    2. TT Mesh Headlight Guard
    3. Givi Wind Screen
    4. TT 20mm Handlebar Risers
    5. TT Hand Guards
    6. Beak Extender
    7. Wind Deflector
    8. TKC-80 Tires
    9. SW-MOTECH Top Rack
    10. Emgo Travel Trunk
    11. Moose Racing Skid Plate
    12. Hepco & Becker Crash Bars
    13. Leovince Carbon Fiber Pipe
    14. Seat Concepts Tall Seat
    15. Cricket Bat Rubber Grips
    16. Power Controller Throttle Fix
    17. Rivco Highway Pegs
    18. SW-MOTECH Center Stand
    29. Garmin Nuvi 2595LMT GPS
    20. R&G Radiator Guard
    21. Hepco & Becker Side Racks
    22. Caribou/Pelican Hard Cases
    23. Camel ADV 2 Gallon Gas Tank
    24. Osram 65 watt headlight bulbs

    The plan so far:
    1. Test ride the bike with top and side cases on and off to see if the handlebar wobble or vibration changes
    2. Take it to BMW Motorrad to see if they can fix it by tightening various bolts or adjusting the suspension
    3. Purchase Scott's steering stabilizer, Ricor fork valves, soft rubber waffle grips, soft thick leather gloves
    4. Consider dumping the TKC-80 tires for less knobby ones and maybe completely upgrading the front forks

    From the web:
    - Shortening the spacer length used in the forks can help with head shake (What spacers is he talking about?)

    - Cranking up pre-load and raising the forks 2-4mm can help by adding weight to the front
    (As far as the fork clamp goes, I thought it was the opposite and the longer the forks the more stable and slower turning and the shorter the less stable but faster turning. When I installed the bar risers I actually adjusted the forks to be nearly flush with the top of the clamp to get every last bit of height out of them to to compensate for my adding preload height and tall seat height to the rear)

    - Tightening the steering head bearing can cut down on steering looseness and wobbling

    - Adding a 17 tooth front sprocket would move the vibey RPM range up higher on the spedo

    Any other suggestions? BTW, I weight 195 lbs.

    Thanks!
    #1
  2. The Maz

    The Maz Clueless and lost

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    Have you had tkc's before? You will get more vibration from them. Ive heard people say it was a wobble at higher speeds. If you are new to knobs, it might feel unsettling. Beak extender and larger hand guards will both catch more wind which might exasperate the problem.
    #2
  3. Excite-Bike

    Excite-Bike Been here awhile

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    I had them on my old DR-Z400 with no hand numbness problems.

    The wobbling did begin after the tire install and got worse after the top and side cases were installed.

    But the left hand numbness I think was from day one.
    #3
  4. The Maz

    The Maz Clueless and lost

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    Hope you get things sorted...
    #4
  5. MTrider16

    MTrider16 Ridin' in MT

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    I would definately do #1. I've been able to shift weight forward and induce a high speed wobble by turning up the preload on the rear shock and raising the forks a little. However you are doing just the opposite by weighting the rear. Thus I'm not sure what kind of results you would get. I would definately set your suspension sag and see if the behaviour changes.

    I run TKC (something like 6 sets) and don't have a wobble, so unless you have a badly unbalanced tire, I wouldn't think it would be the tires.
    #5
  6. RedHawk47

    RedHawk47 Adventurer Supporter

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    moving the fork tubes in the clamps changes the geometry. I know that the F800gs has a specified amount that is to be above the clamp - but it is a different fork than the F650. (While writing this I realized that this may be why my F800 steering feels weird. I thought it might be because I had been riding another bike and had not ridden it in a while. However, I recently had the fork seals replaced - perhaps they put the fork tubes in the wrong position. I'm out of town so I cannot check that until Sunday).

    I suggest moving the forks tubes back to spec and checking the head bearing adjustment. Too tight can cause them to brinell. Brinelled or too loose can cause wobble.
    #6
  7. Excite-Bike

    Excite-Bike Been here awhile

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    Ok I just took off the top and side cases and got it up to 110mph on the freeway with no wobbles at all so I guess it's not the tires which now that I recall were installed the same day as the top rack and case.

    So now I'll go back and install the cases and try again. Side first, then top, with all of them empty.
    #7
  8. CycleDoc59

    CycleDoc59 Wrench Rider

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    It is quite common to have head shake if the fork
    angle is changed. A properly set up bike drops an
    equal amount at each end when loaded. Which is
    why the rear spring preload is adjustable. Often the
    factory adjustment is not sufficient for heavily loaded
    bikes.

    Moving the forks up is a remedy, as is use of shorter front
    spacers - if installed. This lowers the front of the bike to
    better match the rear height.

    Loading the rear of the bike - passenger/luggage, is the
    primary cause of head shake; if the bike is not leveled,
    expect head shake....

    But there are many other things to consider, such as tire
    pressure (more needed for added weight) steering head
    bearing tightness/condition, tire condition/balance/trueness,
    wheel bearing condition, rear swing arm bearings/tightness...
    #8
  9. Excite-Bike

    Excite-Bike Been here awhile

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    Ok, now I just got back from hitting the freeway with the side cases installed *empty* and was able to hit 110mph without any significant wobbles, though the wind resistance and resultant twitchiness was noticeable at such speeds no scary gyroscope wobble developed.

    So now I'll add on the top case *empty* and make a run before loading any of them with weight.

    And just for the sake of argument, what kind of effects might arise from loading the case on one side with heavy tools and the other with lightweight gear?
    #9
  10. CycleDoc59

    CycleDoc59 Wrench Rider

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    It would then be easier to fall down on the overloaded side..(?) Actually,
    the bike would have to steered with slight counter-steering, much like
    compensating for wind from one side. Not dangerous, should not cause a wobble in itself,
    but not wise to heavily load only one side...

    Also, a top case on some bikes can cause "wind wag", as turbulence
    hits the box from different angles, the bike wanders a slight amount.
    Harleys can have that problem. Your bike should not...
    #10
  11. Woody2627

    Woody2627 Grey Wobbler

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    Screen could be an issue.
    #11
  12. CycleDoc59

    CycleDoc59 Wrench Rider

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    If it might help, my '10 F650 has a pair of Micatech bags,
    a Vario topbox, a large tank bag and Madstad windshield.
    Fully loaded, including a tent and chair across the seat,
    and running well-worn miss-matched tires, It tracks perfectly
    w/no tendency to "wobble" at 76mph. (2,500 mile trip in
    Nov at mostly that speed..) And it still handles
    nicely on bumpy, twisty back roads...
    #12
  13. MTrider16

    MTrider16 Ridin' in MT

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    You should probably check out the comments in Fark Spring Rates thread.
    #13
  14. Indy Unlimited

    Indy Unlimited Long timer

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    Check your sag numbers I bet your rear end is squating too much and causing the front end to be to light. Most likely you will need a much heavier rear shock spring. Might as well change the front end springs to match your sag needs and run the forks 20 mm higher in the triple trees. Also some front tires are less stable so you may want to try another front the next time you change tires.
    #14
  15. BMW-K

    BMW-K Unmitigated Bastard Supporter

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    This was my first thought. You've made a bunch of adds to the bike but haven't changed the suspension. Now the bike just isn't coping the way it should.
    #15
  16. Roy Barnes

    Roy Barnes Riding for the SON

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    The Maz is right on. you are going from radial to byis ply tires.
    #16
  17. MTrider16

    MTrider16 Ridin' in MT

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    He has 19" and 17" combo. Not sure if that would make a difference, but my F8 has 21" and 17" and wobble isn't an issue with my TKC's. Vibs maybe, but my bike seems to trasmit engine vibs. I would make sure all the weights are in the bar ends with the new bark busters.

    I'm having a hard time verifying the bias vs radial comment. The TKC are built by Conti for the R12GS which implies a heavy load rating that would come with radial. The are not a full off road tire, but a dot approved dual purpose. Do you have info on the bias tire rating?
    #17
  18. GeeK_InsiDe

    GeeK_InsiDe Moore Gas!!!

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    I made a 2up trip with 30kg zega pro sidecases and a 11kg bag instead of a topcase, plus gf on my 700GS with Karoo 3 tires.

    No wobbles at all but you have to adjust your suspension.
    #18
  19. Excite-Bike

    Excite-Bike Been here awhile

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    It's the top case.

    As soon as I put it back on and hit the freeway the bike started noticeably wobbling over 75 mph.

    So now what? I want a hard lockable top case on this bike.

    I'm not sure why the top case would cause the wobble and if a better one might not. It is a cheap $60 universal style case. I have it mounted quite firmly but where the Caribou-Pelican side cases could probably withstand a grenade blast, the plastic of this Emgo case is so thin and flimsy I could cut it open with a kitchen knife. Also if you grab it by its handle and muscle it around it does indeed sway around where you push it, which I suppose the wind could be doing.

    http://www.amazon.com/gp/product/B000GVD0VE/ref=oh_aui_search_detailpage?ie=UTF8&psc=1

    So should I fill it up with some weight to see if that helps?

    Or should I just rip it off and buy a new high quality case that may be more aerodynamic but certainly more sturdy?

    This was the one single cheap mod I thought I could get away with on this bike. I'm just glad it wasn't something much more serious or expensive.

    [​IMG]
    #19
  20. Excite-Bike

    Excite-Bike Been here awhile

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    By the way, was it just my imagination, or could there also be some connection between high speed wobbling and riding on grooved hard cement sections of the freeway as opposed to smooth soft black top? :scratch
    #20