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Thread: Mushy brakes & Brake Flush - what's up? 2007 R1200R

  1. #1
    Barback King rapiddog's Avatar
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    Question Mushy brakes & Brake Flush - what's up? 2007 R1200R

    I had an issue where the brake lever was pulling back nearly to the handlebar before braking began.
    Actually not quite that severe but was worse/more pronounced in hot weather.
    The first inch of pull there was nearly nothing, ten it would catch and brake if that makes sense.

    So, I took the bike in for a complete system brake flush and everything was great.
    Lever was firm and braking with just one finger.

    2 month later and 2 rides, maybe 300 miles and I can feel it's starting again.
    The first inch of lever pull and it's almost nil before the brake begins to actuate.
    Makes braking notchy.

    Called the dealer, service guy tells me that they can't honor anything because it's been too long since the flush.
    He said it may be a bad master cylinder or 'maybe some air got in the system'...
    So I assume I'd have to pay for another flush and $95 an hour for them to 'diagnose'.

    I'm a bit miffed at having to do the dealer dance.
    Can't talk to a wrench. They are all back in the inner sanctum.
    In L.A. you are at the mercy on dealrism...

    Oh how I long for the good old days.

    2007 R1200R with ABS
    13K miles
    Last edited by deilenberger; 09-15-2013 at 01:06 AM. Reason: added year/model to title
    "...the burble of my exhaust unwound like a long cord behind me. Soon my speed snapped it, and I heard only the cry of the wind...." Larry of Arubia

  2. #2
    Survivor akbeemer's Avatar
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    The R1200R is a fairly simple bike to do a brake fluid flush on. There are detailed instructions in the DYI section of the Hexhead forum. Take a look and maybe you'll see that it is a job you can handle.
    Kevin Huddy
    Tm Pterodactyl MT Outpost

  3. #3
    Barback King rapiddog's Avatar
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    I've bled several ABS systems, R11S, R1150RT, etc
    I do all my own maintenance.
    This time due to time I decided to bite the bullet and get it done by a 'pro' thinking it would be a sure thing.
    There in lies the frustration...
    "...the burble of my exhaust unwound like a long cord behind me. Soon my speed snapped it, and I heard only the cry of the wind...." Larry of Arubia

  4. #4
    Ponch ponch1's Avatar
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    Make it Progresso or make it yourself.
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  5. #5
    Barback King rapiddog's Avatar
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    ...let me rephrase this question,

    When I pull the brake lever not much happens the first inch of pull, then the brakes grab and come on strong.
    Just had a brake flush at the dealer 2 months ago.
    Anyone experience similar?
    "...the burble of my exhaust unwound like a long cord behind me. Soon my speed snapped it, and I heard only the cry of the wind...." Larry of Arubia

  6. #6
    Benchwrenching PGlaves's Avatar
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    I have had a similar experience on the rear brake on Voni's F800. I will bleed the brakes until there is no air and a very solid pedal with little travel. After a couple of months it will begin to require more pedal travel and to feel somewhat soft. When I re-bleed the brakes there will be a little bit of air in the system. There is no sign of fluid leaking out anywhere.

    I am fairly sure that the air is being sucked in past the master cylinder piston but it could be past the wheel caliper piston too. I can't be sure. I haven't yet thrown parts at it to cure the problem, but I watch it very carefully so as soon as I detect abnormal pedal travel - I marked a line on the engine case with full pedal depression right after it was bled - I bleed the system again.
    Paul Glaves - "Big Bend", Texas U.S.A
    "The greatest challenge to any thinker is stating the problem in a way that will allow a solution." - Bertrand Russell
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  7. #7
    Barback King rapiddog's Avatar
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    I wouldn't worry about it and it's livable but it makes braking hard (er) to finesse.
    After the brake flush I was spoiled, amazed how much better the bike braked.
    Frustrating...
    "...the burble of my exhaust unwound like a long cord behind me. Soon my speed snapped it, and I heard only the cry of the wind...." Larry of Arubia

  8. #8
    A bozo on the bus deilenberger's Avatar
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    Lightbulb

    Actually - one of "they all - or most - of them do that.." with the R1200R. I chased it for quite a while, and after discussing it with someone I really trust on braking systems decide it's somewhat normal. The R1200R front calipers are different than other R1200 models. Like most calipers they use a square seal that rolls a bit when the piston is extended (brakes applied) and is by design supposed to pull the piston back away from the pad just a tiny bit when the brakes are released.

    As the pads start to wear - the pull-back seems to grow a bit. I did the same with flushing the system, and had the same result. It was initially firm, then it started to grow a bit of freeplay. Nothing excessive or dangerous (you can adjust the lever away from the grip with the screw adjuster), just enough to be noticeable. I did get the master cylinder replaced under warranty (the dealer's diagnosis) - and again - initially it was nice and tight, and it gradually gained more freeplay.

    The GS911 has a function to bleed the ABS modulator which seems to have helped just a bit, so if you know someone with one, doing that with new pads and a flush might make it stay firmer longer, but I wouldn't count on it. Eventually you won't even notice it..
    Don Eilenberger http://www.eilenberger.net
    Spring Lk Heights NJ NJ Shore BMW Riders New Sweden BMW Riders
    '07 R1200R (current ride) and some bimmers.. and a Porsche

  9. #9
    Barback King rapiddog's Avatar
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    Thumbs up Gratsi!

    Thankyou Thankyou and Thankyou!
    This is the answer I was looking for, though not the good news..

    Much apreeciated.
    I wouldn't have noticed the improvement had I not had the brakes bled, but they where in dire need anyway.
    It was getting so the lever was pulling nearly to the bar , especially in hot weather as I said.

    I asked the service guy if the price included a 'complete system flush' as described in the maintenance schedule.
    He said it did.
    I'd assume that meant the ABS modulator...
    "...the burble of my exhaust unwound like a long cord behind me. Soon my speed snapped it, and I heard only the cry of the wind...." Larry of Arubia

  10. #10
    A bozo on the bus deilenberger's Avatar
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    BTW - since I'm back home at the main computer.. (after 3,200 miles of bliss on the R12R..) per: http://www.bmwmoa.org/forum/showthread.php?46055 - I'm adding year/model to your thread title.
    Don Eilenberger http://www.eilenberger.net
    Spring Lk Heights NJ NJ Shore BMW Riders New Sweden BMW Riders
    '07 R1200R (current ride) and some bimmers.. and a Porsche

  11. #11
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    Don, Rapidog
    No debate about what you're experiencing with systems but not sure the explanation re seal pullback makes any sense.
    Yes, square seals are the norm in most stuff and they are cut/installed in a manner to create pad pullback. What I don't get is how some use can have any effect to increase that compared to a new system. Never seen it in all the brake systems I've mssed with, admittedly mostly cages, but in extreme use conditions.

    What I have seen a bunch of is increased pad knockback caused by a whole bunch of different things, from flexing mounts to shaking wheels by imbalance from about anything you can imagine (eg handfuls of gummy worms collecting on the inside of the wheel). The knckback created extra pedal travel can be an issue for simply having adequate brakes but more often is significant nuisance because by creating extra pedal travel it interferes with proper "heel and toe" (which in reality is both sides of one foot) simultaneous control of brake and gas pedal.

    Anyway, cage racers have a simple fix for this that I've never seen anyone use on a bike but in principle it should work the same. What is done is inserting a small very light pressure spring into the caliper behind the piston to provide a very light steady pressure. Keeps pad travel to a minimum without creating excess pad heat or wear. For racing cage calipers. like APs, these are available from caliper makers and their wholesalers/dealers. They are 1 lb-2 lb rated springs for disc brakes.
    If I wanted to experiment with this for a bike I'd get the lightest spring that would fit from one of the brake system dealers and give it a go.

    Knockback tends o be a self limiting thing- any wheel mount system has a max amount of knockback it will allow and once that amount has been reached it gets no worse.

  12. #12
    A bozo on the bus deilenberger's Avatar
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    The reason I feel it's seal pullback is simple. If the bike is stationary (none of the external influences you mention), first time you pull the lever it comes with about 1" of the grip. If you release and then pull it again immediately - it comes to about 1.5" from the grip. If you release and then wait about a minute and pull it, it's back to the 1" position.

    The only thing I can think of that would account for that is the seal pullback. There really isn't anything else going on. Air in the system won't make that happen (it will always feel mushy.) And it happens more when the pads are worn. With new pads it's not really noticeable (which is how they sell new bikes I guess..)
    Don Eilenberger http://www.eilenberger.net
    Spring Lk Heights NJ NJ Shore BMW Riders New Sweden BMW Riders
    '07 R1200R (current ride) and some bimmers.. and a Porsche

  13. #13
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    I can understand the variable aspect but not any relationship to older pads.
    Seals provide only a few thousandths of movement and that amount is virtually nothing compared to pad thickness.

    Variability can sometimes be caused by tiny air bubbles trapped somewhere that move around. Most often this is in the m/c but can be anywhere (many do not know how to properly bleed a master cylinder- the best way by far is the recirc loop method because it provides visual proof that all bubbles are gone- they are sometimes very difficult to remove and simply pushing a small amount of fluid out the bleeder may not do it on some systems). Am not familiar enough with the line routings on the R to suggest any more specific location. As you know, a characteristic of many problems caused by air bubbles is that the system can be "pumped up" to minimize them and if pumped rapidly stays that way- then if left for a while returns to the previous state.

    The problem you describes seems to be model specific in that its not something I've heard reported for other models. So the obvious question would be what is unique about the R brakes? Are the calipers, m/c's and other bits the same as other models, for example, or are the seals and caliper design unique? The line routing would have to be somewhat different but what else is?

  14. #14
    A bozo on the bus deilenberger's Avatar
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    Quote Originally Posted by racer7 View Post
    The problem you describes seems to be model specific in that its not something I've heard reported for other models. So the obvious question would be what is unique about the R brakes? Are the calipers, m/c's and other bits the same as other models, for example, or are the seals and caliper design unique? The line routing would have to be somewhat different but what else is?
    As I mentioned above - the calipers ARE specific to the model. AFAIK, it's the only R1200xx model using these calipers (which are by Brembo..)
    Don Eilenberger http://www.eilenberger.net
    Spring Lk Heights NJ NJ Shore BMW Riders New Sweden BMW Riders
    '07 R1200R (current ride) and some bimmers.. and a Porsche

  15. #15
    Benchwrenching PGlaves's Avatar
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    Based on the discussion it seems the first thing the OP needs to do is figure out if the problem is the caliper pistons retracting; or, air in the system. On Voni's F800 it is absolutely air being drawn into the system. On Don's it seems to be the pistons witdrawing too far requiring that they be poushed back before the pedal/lever is firm again.

    Some careful observation, a feeler gauge, and maybe a careful bleed looking for bubbles seems to be in order.
    Paul Glaves - "Big Bend", Texas U.S.A
    "The greatest challenge to any thinker is stating the problem in a way that will allow a solution." - Bertrand Russell
    http://www.bigbend.net/users/glaves

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