F800GS: Anyone done 17" front?

Discussion in 'Parallel Universe' started by Steffo, Dec 3, 2009.

  1. Schtum

    Schtum Free Genie

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    Sorry Mac but I think you'll find this is incorrect. The computer takes into account the difference in rotation speeds between the front and rear wheels and uses this information to make decisions about ABS operation. So if you fit different sized wheels you have to re-program the ECU to take account of this, otherwise you bugger up the ABS operation.
    #61
  2. grndzr0

    grndzr0 its Ground Zero

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    Not sure where I read it... but one of the BMW techs around here said that when you first start moving, it is sort of an ABS calibration period. At this time, it figures the difference in wheel speeds for different size wheels. Also, several people have done wheel size conversions without reprogramming anything and did not have any adverse effects.
    #62
  3. Schtum

    Schtum Free Genie

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    If that's correct then that's great and it might be that's why it takes a couple of wheel revolutions before the Brake Failure light extinguishes each time you fire up the bike and ride off. However, I think it's as well to know that and the fact that the ABS begins to take effect long before the wheels lock up.
    #63
  4. grndzr0

    grndzr0 its Ground Zero

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    true, it does measure a difference in wheel speeds. This is why the ABS does not work if one sensor is missing or broken..
    #64
  5. Steffo

    Steffo Been here awhile

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    On the ABS..

    What I did was to order a new ABS rotor, for 17" front wheel, with the new wheel and it works flawlessly.

    I have only one regret with this new wheel. I should have done it two years ago. :evil
    #65
  6. nutter_on_the_bus

    nutter_on_the_bus Who? Me?

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    Steffo

    Where did you get the new ABS ring from? With the original one the ABS switches off after hitting 30.
    #66
  7. nutter_on_the_bus

    nutter_on_the_bus Who? Me?

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    as search engines often come up with unfinished queries

    I have come across a Wunderlich part for the old F650GS single, http://www.wunderlichamerica.com/motorcycle/8160576.html which is the ABS ring for their 17" conversion for the single,and as this has the same PCD it should solve the problem.

    Tried this and it works. :D
    #67
  8. Hamish71

    Hamish71 Been here awhile

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    So, apologies if reviving an old thread is a crime but I have read many many threads, on many forums trying to resolve this issue.

    It would appear, you CAN, fit a 17 inch wheel to the front, as long as you use the wunderlich part for the abs ring. Correct?

    As an alternative, has anyone made the F800R front wheel fit the f800gs yet?
    #68
  9. sailer

    sailer trained Cirus Bear

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    My winter project
    #69
  10. tazakos

    tazakos F800gs black&yellow

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    did u do it?
    #70
  11. Motorfiets

    Motorfiets Long timer

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    :evil

    [​IMG]
    #71
  12. tazakos

    tazakos F800gs black&yellow

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    wow, a beast! where is the front system from?
    nice work man:clap
    #72
  13. Motorfiets

    Motorfiets Long timer

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    it is a WP ktm front end with a ktm SM wheel
    #73
  14. tazakos

    tazakos F800gs black&yellow

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    sorry for repeating the question, but which KTMs front end was that? do you still have ABS?

    thanks a lot
    #74
  15. Baitfish

    Baitfish Adventurer

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    I decided to see if I could have 2 bikes in 1.
    I got sick of changing between road and dirt tyres depending on who I was riding with, so the obvious solution was 2 sets of wheels with tyres and brakes ready for quick swaps.
    Even better, how about tubeless 17" super sticky road rubber to really mess with the sports bikes :evil.
    For playing in the dirt it looks like this -
    [​IMG][​IMG]

    And here's what it looks like with a 120/70-17 on a 3.5" front and 180/55-17 on a 5.5" rear ready for the street -
    [​IMG]

    Uses custom lasercut ABS rings to keep the speedo correct and the ABS happy.
    Changeover is pretty quick if I don't remove the pannier racks, bash plate toolbox, etc. Simply pull axles, swap wheels, drop rear preload, add 1/2 turn rear damping, add 4 clicks front compression and 4 clicks front rebound damping.
    Turns like a sports bike. :clap Sports bike wheels are light too. :wink:
    Probably need a lower front guard to complete the look but that's just another time adder when changing over.

    I doubt this will be one of a kind for long, I already have 3 mates with F8s (all serious dirt riders) who want me to do a set of 'tards for them too.

    [​IMG]
    #75
  16. klimtachakka

    klimtachakka Adventurer

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    Sweet!
    Where did you get the wheels from?
    #76
  17. Baitfish

    Baitfish Adventurer

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    Any 600+ sports bike.
    Pick something with 20mm bearings to make it easier.
    5.5" seems to be as wide as possible for the rear, so modern liter sports bike wheels (6") are out of the question.
    Mine were Kawasaki wheels.
    Had to make axle spacers and some adapter plates for the brake rotors as well as the ABS rings.
    Took a little more time than I expected but most of that was making sure everything would go together. And it does. :clap
    #77
  18. ReBandeira

    ReBandeira n00b

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    Hello friends, I'm Alexandre Marques, Sao Paulo - Brazil. I have a F 800 GS bike and changed the front wheel rim 21 by another rim 17, after some time running, the ABS stops working, anyone have solution for this problem? Thank you.
    #78
  19. Baitfish

    Baitfish Adventurer

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    ABS usually stops working because the computer sees a fault when there is a difference in the wheel speeds. You need a different ABS ring for the front wheel - it has to have less slots. Stock one has 48 slots, you need one with about 41 slots. My road wheels have 41 slot front and 46 slot rear and the dirt wheels have the stock 48 slot front and rear. Speedo is as accurate on the road wheels as it is with the dirt wheels (107 indicated = 100 on GPS) and the ABS works fine.

    Disclaimer :deal: Those slot counts suit my choice of road tyre size - 120/70-17 Front & 180/55-17 Rear and may not be correct for your tyre choice. They will be a lot closer than the stock ones though :wink:

    So, what 17" front wheel did you use?
    #79
  20. ReBandeira

    ReBandeira n00b

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    Thank you for your interest in replying friend.
    Front wheel use Michelin 120/70 ZR 17.
    Where can I buy the ring that matches?
    #80