2010 F800GS Brake Lever Swap

Discussion in 'Parallel Universe' started by Gebirgekind, May 9, 2020.

  1. Gebirgekind

    Gebirgekind Rockies

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    I've got to overhaul the front brakes on my '10 F800GS, and thought it might be a good time to get rid of the old bobble head reservoir. I'd like to get away from the plastic entirely and move to an integrated reservoir/lever.

    Is there any reason I couldn't use the newer (2013+) R1200GS lever/cylinder assembly? Would there be any issues with the ABS or wiring?

    I know in the past folks have successfully used the KTM 950/990 levers, but it requires some rewiring. I can find used BMW and KTM assemblies for around the same price, so was just hoping the newer R1200GS would be a cleaner swap over.

    Thanks for your collective wisdom!
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  2. JRWooden

    JRWooden Homeless motorcycle vagabond ... and ... loving it

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    There's an old thread on it here:

    https://f800riders.org/forum/showthread.php/36114-Change-the-Brake-Fluid-Reservoir

    My comment:
    It was originally thought that the bobble-head was there because there was a risk of "foaming" of the brake fluid.
    It later years of the twins, the bobble-head went away, but AFAIK no one knows if there there other changes to the design to mitigate the "foaming"
    issue or if BMW just figured out it wasn't an issue and went back to a traditional mounting ...

    and for good measure here is a comment from a thread somewhere on ADVRider (sorry don't have a link ... ):

    To answer your question, you would most likely get away with it knowing that the conditions that cause a problem are so rare. As for fitment you'll have to figure it out. If you *must* have it then I'd also buy the foam insert used as a band-aid in the K bikes. It's a cheap large celled yellow insert that fits into the front brake reservoir and is supposed to dampen the vibrations of the fluid enough to save lawsuits. No one is going to tell you "yeah, no prob, you'll be fine, no worries mate!"
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  3. Duitser

    Duitser Been here awhile

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    They used to call it the flying urine sample
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  4. bmwroadsterca

    bmwroadsterca RadioFlyer

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    Your 2010 has a microswitch at the lever to activate the brake light. Later years used a pressure switch at the ABS unit. Whatever you use you need to account for how the brake light is to be actuated.
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  5. Gebirgekind

    Gebirgekind Rockies

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    Thanks @bmwroadsterca, that's what I was wondering. What kind of mod would that take for the pressure switch? Would I have to replace the ABS unit as well, or is there a way to rewire at the master cylinder? Could I make the newer R1200GS cylinder work with the microswitch?

    Electronics are my Kryptonite :D. Thanks for your help!
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  6. bmwroadsterca

    bmwroadsterca RadioFlyer

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    The master cylinder you choose may have a switch built in. In that case wire the switch to the existing connector or harness. If not you can buy a pressure switch.and you would have to plumb it in and connect it. Since the wires are already present at the handlebar it would be easiest to plumb the switch at the master cylinder.
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  7. Gebirgekind

    Gebirgekind Rockies

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    That makes perfect sense now, and easy enough to plumb something in if needed. I appreciate your experience! Thanks again everyone, happy riding!
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  8. ROMAD

    ROMAD Been here awhile

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    When swapping out any MC you want to ensure the Piston diameter is the same, unless you know exactly why you need a bigger/smaller diameter as the effects are usually backwards from what people think will happen.

    I used one off an 04 R1200GS and it works like a champ and got rid of the bobblehead. The resevoir is white in color like the rear MC but there are others out there with the smoked color resevoir if that's what you want.
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  9. Gebirgekind

    Gebirgekind Rockies

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    Thank you everyone for your tips. With your help and some time with various microfiche, I've gathered some helpful data that may benefit others here. I'll post it on the original forum about this swap as well. It seems like others have had success with master cylinders from a variety of sources, so compatibility is up to rider and riding style. Here are some definitive numbers for anyone looking to change:

    F800GS all years: 15mm master cylinder, driving 2 x 2-pot calipers, 30mm and 32mm

    KTM 640/950/990: 15mm master cylinder, driving 2 x 2-pot calipers, 30mm and 32mm - replaces remote plastic reservoir with integrated, cast reservoir; requires relay to change microswitch from normally open (KTM) to normally closed (BMW). Instructions here: https://advrider.com/f/threads/hydraulic-brake-light-switch-with-reversed-switching.629811/

    R1200GS all years: 16mm master cylinder, driving 2 x 2-pot calipers, 32mm and 36mm - some report success with this swap

    Direct Mounting R1200GS Plastic Reservoir to F800GS Master Cylinder, part #32727723416 - this essentially matches the change BMW made with the 2013+ models; consider using the foam insert as well for alleged foaming issue


    For single disc conversion:


    G650GS (Sertao): 13mm master cylinder, driving 1 x 2-pot caliper, 30mm and 32mm - replaces remote plastic reservoir with intergrated, cast reservoir

    G450X: Unknown master cylinder, driving 1 x 2-pot caliper, 28mm and 28mm - replaces remote plastic reservoir with integrated, cast reservoir; Twalcom had success using this MC with a single F800GS caliper on their Erzberg Rodeo race bike
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