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Thread: Is My Timing Wrong? Or When to Bleed Brakes?

  1. #1
    RK Ryder
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    Is My Timing Wrong? Or When to Bleed Brakes?

    With both my K100 an R1100 RTs, I put them away for the winter with a full service, either the 10,000 or 20,000 km, with the exception of bleeding the brake lines. That I do in either late March or early April before either bike is back on the road.

    It has been bought to my attention that bleeding the brakes would better for the system if done before the bikes sit for the winter, rather than in the spring.

    So, spring brake bleeding or just before winter hibernation?
    Paul F. Ruffell
    Retired and riding my RTs, the '87 K100 & the '98 R1100 !
    Niagara Riders & Knights of the Roundel #333

  2. #2
    Liaison 20774's Avatar
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    I'm going to add a little context to the thread title. I thought it might have been about ignition timing!
    Kurt -- Forum Liaison ---> Resources and Links Thread <---
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    mine-ineye-deatheah-pielayah-jooa-kalayus. oolah-minane-hay-meeriah-kal-oyus-algay-a-thaykin', buddy!

  3. #3
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    Quote Originally Posted by 20774 View Post
    I'm going to add a little context to the thread title. I thought it might have been about ignition timing!
    So did I!!
    To lend a prospective to the question.
    I would most certainly bleed the brake system when the fall service is done.
    Brake fluid attracts moisture, when moisture and brake fluid are mixed together it becomes acidic. Thre mixture then eats away at the aluminum in your master cylinders and calipers. Think about the riding you did all season, the weather you rode through, the temperture changes from warm days to chilly evenings. These conditions creat condensation in your system, that brake fluid is sitting in your brake system through out the winter. Replace it with new and clean for storage. My $.02....

  4. #4
    Fortis Fortuna Adiuvat Omega Man's Avatar
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    Quote Originally Posted by CNRed View Post
    So did I!!
    To lend a prospective to the question.
    I would most certainly bleed the brake system when the fall service is done.
    Brake fluid attracts moisture, when moisture and brake fluid are mixed together it becomes acidic. Thre mixture then eats away at the aluminum in your master cylinders and calipers. Think about the riding you did all season, the weather you rode through, the temperture changes from warm days to chilly evenings. These conditions creat condensation in your system, that brake fluid is sitting in your brake system through out the winter. Replace it with new and clean for storage. My $.02....
    I like this explanation.
    I donít worry a ton on BB as it is a sealed system unlike the constant opening and closing of a fuel system (ethanol) allowing the accumulated moisture to cause the same corrosion problems.
    OM
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  5. #5
    Left Coast Rider
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    Agreed with all of the above. Change all the fluids and be ready for spring.

    And if you haven't already, change any rubber brake lines for something from Spiegler.

  6. #6
    rabid reader dbrick's Avatar
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    Quote Originally Posted by Omega Man View Post
    I donít worry a ton on BB as it is a sealed system unlike the constant opening and closing of a fuel system (ethanol) allowing the accumulated moisture to cause the same corrosion problems.
    OM
    I disagree. A vehicle hydraulic system is not sealed, as there must be a way for air to enter (and leave) the system to accommodate pad wear. Pad wear will cause the wheel cylinder pistons to "rest" in different positions within the wheel cylinders, thus affecting the working volume of fluid within the system.

    It's not a lot of air, as the volumes we're talking about in bike systems are small. But air does enter, and over time, brake fluid is degraded. There's a reason the manufacturers put "brake fluid replacement" in the maintenance schedules. On bikes, fluid change is usually called for at shorter intervals than in cars and trucks, because a) the master cylinder (where the vent must be located) is more exposed to weather on the handlebar compared to a car's master cylinder under the hood, and b) because a car's system, being larger, has a larger volume of brake fluid, and can tolerate a longer period between changes.

    As to changing in the fall of spring, I think fall makes the most sense.
    David Brick
    Santa Cruz CA
    2007 R1200R

  7. #7
    RK Ryder
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    Well I will now have one less task to perform in the spring since I'll be bleeding the brakes in the fall.

    Thank you to all who replied.

    Besides doing the bleeds in the fall, would there be any advantage to doing a partial bleed mid-summer or is the fall service sufficient for all of the following riding season?
    Paul F. Ruffell
    Retired and riding my RTs, the '87 K100 & the '98 R1100 !
    Niagara Riders & Knights of the Roundel #333

  8. #8
    '99 '03 '06 National Co-Rally Chair Friedle's Avatar
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    When bleeding brakes, make sure you use ethanol free genuine BMW supplied leeches exclusively !

    Friedle
    Ride fast safely

  9. #9
    RK Ryder
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    Quote Originally Posted by Friedle View Post
    When bleeding brakes, make sure you use ethanol free genuine BMW supplied leeches exclusively !

    Friedle
    Excuse me, but I thought that everyone used the ethanol free genuine BMW leeches! If they didn't, how could they possible get ride of those pieces of gunk that are otherwise impossible to remove from the lines?
    Paul F. Ruffell
    Retired and riding my RTs, the '87 K100 & the '98 R1100 !
    Niagara Riders & Knights of the Roundel #333

  10. #10
    Registered User WWeldin's Avatar
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    Does fresh fluid absorb less moisture than 1 year old fluid? Seems like it would be affected by the same condensation through the time of the storage.
    2000 R1200C, 2019 R1250RT

  11. #11
    Registered User AKsuited's Avatar
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    FWIW, I figure the best time to change brake fluid is when the humidity is lowest to keep from absorbing moisture during the fluid change, which for me would be mid-winter. The bike resides in the mudroom I built for it at the back of my house and connected to the house. The air is shared with the house and that air is driest mid- or late-winter.

    Harry
    My fleet: 2015 R1200GS, 2017 Toyota Prius Prime (plug-in hybrid)

  12. #12
    RK Ryder
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    Quote Originally Posted by AKsuited View Post
    FWIW, I figure the best time to change brake fluid is when the humidity is lowest to keep from absorbing moisture during the fluid change, which for me would be mid-winter. The bike resides in the mudroom I built for it at the back of my house and connected to the house. The air is shared with the house and that air is driest mid- or late-winter. Harry
    My very well insulated garage is attached to my house. The garage's temperature varies throughout the winter between 45-50 F and up into the low 60s with a small heater when I working out there. The 13' high ceiling has fan, always on, pushing the rising warm air, back down.
    Paul F. Ruffell
    Retired and riding my RTs, the '87 K100 & the '98 R1100 !
    Niagara Riders & Knights of the Roundel #333

  13. #13
    Left Coast Rider
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    Quote Originally Posted by AKsuited View Post
    FWIW, I figure the best time to change brake fluid is when the humidity is lowest to keep from absorbing moisture during the fluid change, which for me would be mid-winter.
    Where I live that would be mid-summer. Relative humidity in my heated garage is 76% right now. In the summer its about 40% or so. Your theory makes sense but I'm not sure it makes a practical difference.

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