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Thread: Senior Moment: Brake Bleeding

  1. #1
    RK Ryder
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    Senior Moment: Brake Bleeding

    Am I correct in remembering that when filling the front brake reservoir, the level should be at the halfway mark of the sight glass? (With DOT 4 of course. )
    Paul F. Ruffell
    Retired and riding my RTs, the '87 K100 & the '98 R1100 !
    Knights of the Roundel #333

  2. #2
    SURVIVOR akbeemer's Avatar
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    Can't say that is way it is stated in any manual, but is logical and the way I do it. I just make sure the line of the fluid level is visible in the window. If you can't see it because it is too high or too low, then the window is useless.
    Kevin Huddy
    Silver City, Montana
    MOA# 24,790 Ambassador

  3. #3
    RK Ryder
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    As I thought.

    Thank you Kevin!

    Paul
    Paul F. Ruffell
    Retired and riding my RTs, the '87 K100 & the '98 R1100 !
    Knights of the Roundel #333

  4. #4
    MOA #24991 Pauls1150's Avatar
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    ...with the handlebars centered, so the front wheel is pointing straight ahead.

  5. #5
    RK Ryder
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    Quote Originally Posted by Pauls1150 View Post
    ...with the handlebars centered, so the front wheel is pointing straight ahead.
    😀 That I hadn't forgotten. 👍

    What surprised me was how clean/clear the year old fluid was on both bikes. The R1100 was ridden zero kms last year and the K, only 10,000. COVID, not lack of desire was the reason for such pitiful riding in 2020. 😕
    Paul F. Ruffell
    Retired and riding my RTs, the '87 K100 & the '98 R1100 !
    Knights of the Roundel #333

  6. #6
    Pepperfool GSAddict's Avatar
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    Quote Originally Posted by akbeemer View Post
    Can't say that is way it is stated in any manual, but is logical and the way I do it. I just make sure the line of the fluid level is visible in the window. If you can't see it because it is too high or too low, then the window is useless.
    It is covered in each BMW Model specific CD
    Section 00
    + Checking Brake Fluid Level


    Below are the instructions copied from the CD's

    R1150GS

    Note:
    The volume of the brake fluid (MIN/MAX) is sufficient
    for lining thicknesses from new to the wear limit.
    It is not normally necessary to top up the fluid to accommodate lining wear.
    If the level drops below the MIN mark, this indicates
    some other fault

    Required level with new brake pads:
    (Initial fill quantity)
    .. make sure that no bubbles are visible in the sight
    glass
    • Handlebar centred.
    • Check that the front wheel is on the ground.
    Minimum fluid level
    Brake pads worn: not less than...............................
    ........................................... half way up sight glass
    Brake fluid grade .........................................DOT 4




    R1150RT:

    Note:
    The brake fluid level in the sight glass/brake fluid
    reservoirs of control circuits remains constant despite wear of the brake pads.
    If the level drops below the MIN mark, this indicates
    some other fault.

    Front brake
    • Place the motorcycle on its centre stand.
    • Turn the handlebars fully to the left.
    • Check brake fluid level at sight glass.

    Specified level
    not below .................................................. ....... MIN
    (top edge of the marking ring)
    • Correct the fluid level if necessary.



    R1100S:

    The brake fluid volume (between MIN and MAX) is
    sufficient for the complete range of pad wear from
    new to the wear limit.
    It is not normally necessary to top up the fluid to accommodate pad wear.
    If the level drops below the minimum mark, this indicates some other fault.

    • Handlebar centred.
    Required level
    Brake pads new .............................................. MAX
    • Turn the handlebar fully to the left.
    Required level
    Brake pads worn: not less than........................ MIN
    Brake fluid grade .........................................DOT 4



    R1100 GS, RT, RS, R

    • Remove reservoir cover together with diaphragm.
    • Add brake fluid up to the MAX mark.
    • Fit diaphragm and reservoir cover.
    • Carefully tighten retaining screws.
    Brake fluid grade:
    Use only brake fluid of DOT 4 quality classification
    (e.g. ATE "SL“ brake fluid)




    Image for R1150RT & R1100S
    Attached Images Attached Images
    Last edited by GSAddict; 05-13-2021 at 05:36 AM.
    '
    Ufda happens..........

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  7. #7
    RK Ryder
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    Unhappy

    So the brake bleeding on the R1100 was uneventful and then on to the '87 K100.

    Well it was uneventful until as I was almost finishing the bleed on the K's final front line, the hose slipped off spilling brake fluid on the floor and a bit on the wheel. Spayed the bike and floor, then wheeled the K outside and hosed it down. Never had this happen before as I use a tight fitting hose and always cut the tubing back before putting it onto the nipple and even put a clip over the hose.

    The next morning I re-bled both front Spiegler lines on the K to remove the air that got into the lines. After a full bottle of DOT4, the brakes are now feeling spongy, despite no air bubbles appearing in the fluid being extracted.

    Suggestions to resolve this would be appreciated.

    Paul
    Paul F. Ruffell
    Retired and riding my RTs, the '87 K100 & the '98 R1100 !
    Knights of the Roundel #333

  8. #8
    Pepperfool GSAddict's Avatar
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    Whenever I replace brake lines I fill the lines from the caliper up with a syringe.
    Pushing air up is much easier than pulling down.
    Wrapping the threads with a little teflon tape will seal the bleed screws to avoid any leak by.
    Also helps with the normal bleed process.

    The item on the hose is a shutoff valve.
    Attached Images Attached Images
    '
    Ufda happens..........

    Need your R11xx Hall sensor rewired? PM me.

  9. #9
    Registered User
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    My experience has shown that in many instances on a number of bikes I've owned the front brake will feel spongy for a period of time even when properly bled. I've heard others explain it as "micro-bubbles" needing to work their way upward to the master cylinder. Seemed far fetched but I don't have a better explanation. After a day or two with use the handle always firms up.

    On a few of my bikes, the Ducati's come to mind, depending on the orientation of the front master cylinder it helps to lean the bike to the left as far as you can and pump the handle. Air can get trapped where the line attaches to the master cylinder.... doing this allows it to escape into the reservoir.

    This is where some would add "YMMV".... I won't because I can't stand that expression (grin).

  10. #10
    RK Ryder
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    Overnight I left the cover off the brake reservoir. After my last post this morning, I placed the cover back on and bounced the K off its' centre stand which resulted in full front braking! The bounce must have caused the remaining air bubbles to travel upwards to the reservoir. All appears to be well. Also this morning I picked a few 1/4" hose clamps to secure my 3/8" tubing for future brake flushes. Thanks to GS Addict and GIARCG for their advice on this issue. 👍


    Paul
    Paul F. Ruffell
    Retired and riding my RTs, the '87 K100 & the '98 R1100 !
    Knights of the Roundel #333

  11. #11
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    Paul - Glad it worked out.

    As an FYI brake fluid is hygroscopic (absorbs moisture), it draws it right out the air.... not good for the brake system. Leaving the lid off the reservoir or cap loose on a container is not a best practice. Mentioning with the assumption it was done intentionally.

  12. #12
    RK Ryder
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    Quote Originally Posted by GIARCG View Post
    Paul - Glad it worked out.

    As an FYI brake fluid is hygroscopic (absorbs moisture), it draws it R ight out the air.... not good for the brake system. Leaving the lid off the reservoir or cap loose on a container is not a best practice. Mentioning with the assumption it was done intentionally.
    GRIACG, the purpose in leaving the
    cover off was allow any air in the lines to flow upwards and I did get a number of air bubbles when I pumped the brake lever. There was more resistance this morning than last night. The final couple d'etat at removing the air was obviously taking the bike off the centre stand. If I should ever be unfortunate to have this issue again, bumping the off the centre stand will my first step to dislodge any stubborn air.

    I am not too concerned about a bit of moisture in the K's braking system as I alternate which bike gets ridden the most in a season. This year is the R's turn for the majority of rides and with a COVID summer in Ontario, I am unfortunately looking at only day trips for the second summer in a row. 😠👎
    Paul F. Ruffell
    Retired and riding my RTs, the '87 K100 & the '98 R1100 !
    Knights of the Roundel #333

  13. #13
    Curmudgeon nrpetersen's Avatar
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    Paul F - I just finished installing Spiegler lines on my 2005 K1200LT and had the same experience of a soft front brake and slight amounts of "micro-foam" while bleeding. Again the spongy feeling seemed to disappear as things happened to be left open for a couple of days.

    Yes, each bike (of the 3) has a mission.
    Retired w 2005 K1200LT, 2000 R1100RT, & 1975 R90/6

  14. #14
    Gerard jagarra's Avatar
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    After I finish any brake bleeding and system refill and after I get a good feeling brake I always pump up the lever and wrap a bungee cord around it to hold it on pressure and leave it overnight. The next morning or whenever it always has a nice firm brake action. All the micro bubbles are gone.
    1994 R1100RS-(5/93)-,1974 R90/6 built 9/73,--1964 Triumph T100--1986 Honda XL600R

  15. #15
    RK Ryder
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    Quote Originally Posted by jagarra View Post
    After I finish any brake bleeding and system refill and after I get a good feeling brake I always pump up the lever and wrap a bungeen cord around it to hold it on pressure and leave it overnight. The next morning or whenever it always has a nice firm brake action. All the micro bubbles are gone.
    I pumped the lever a good number of times and than wrapped a velcro strap around the brake handle/handle bar and left it overnight. However the feel was too spongy for my liking in the morning so I took it off the centre stand to ride around our circle. Bike did not need to leave the garage to know that all was well as there was suddenly lots of pressure when pulling the brake lever. The bounce from leaving the centre stand apparently dislodged the remaining air bubbles/pockets. 👍
    Paul F. Ruffell
    Retired and riding my RTs, the '87 K100 & the '98 R1100 !
    Knights of the Roundel #333

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