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

  1. #16
    A bozo on the bus deilenberger's Avatar
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    Quote Originally Posted by PGlaves View Post
    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,

    The feeler gauge is a good idea - but may be tough to actually measure, since the use of the gauge will tend to push the piston back. As far as bleeding - been done quite a few times, both by me and by the dealer. The results don't seem to change. And one point that might have been missed.. if there was air being drawn into the system I'd expect the symptoms to get worse with time. These symptoms don't. The amount of pull on the lever really doesn't change, first stroke is longer than the second, but the first stroke travel is consistent, over a period of months (and thousands of miles) of use. I did the last flush/bleed using the feature on the GS911 that activates the ABS to bleed it. It didn't really seem to make any difference.

    When I had my master cylinder replaced - the mechanic doing it was the shops "master" tech, who also happens to ride an R1200R. His comment was "they all do that.." and "It will feel better for a while, then it will come back.." I know the "all do that" comment is always suspect, but since he rides the same bike, and has the ability and parts to fix it if it was fixable, in this case - I think he wasn't talking nonsense. He was happy to do the job since BMW was paying for it.

    Maybe I'll try figuring out how to mount a dial-indicator so I can read the pad travel.. not sure if that's possible, but I'll take a look.
    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

  2. #17
    Barback King rapiddog's Avatar
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    The amount of pull on the lever really doesn't change, first stroke is longer than the second, but the first stroke travel is consistent,...
    That's exactly right. The day I had the brakes flushed by the dealer the lever was at full pressure right at the atart of the lever stroke.
    I liked the brakes on this bike more than any boxer I've owned, but I was even more impressed with them up to snuff.
    Now I'm back to square one.

    I traded my R12RT for this bike back in November last. The R12R had 11+K miles.
    I did a full 12K maintenance on it including bleeding the brakes at the calipers.

    Not sure I mentioned, the brakes seemed fine for the first 6 months I've owned the bike, but then started getting progressively worse at the lever.
    When the hot SoCal weather came the lever was pulling nearly to the grip.
    That's when I decided to take it in.
    "...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

  3. #18
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    Not familiar with line routing on the R. Any chance any of the lines go someplace where they pick up motor or exhaust heat? That would expand any air bubbles or encourage air dissolved in brake fluid to create new bubbles. (Doesn't seem that it should be all that different than any other R1200 model where they go up over the tank from the routing up the fork- but I don't service any R1200R's so don't know)

    Seen a few track cages with this sort of problem where some teams have gone to extreme of heating brake fluid to drive out dissolved gases before filling a system. Others (more commonly) just end up bleeding these things after every track session...

  4. #19
    A bozo on the bus deilenberger's Avatar
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    Quote Originally Posted by racer7 View Post
    Not familiar with line routing on the R. Any chance any of the lines go someplace where they pick up motor or exhaust heat? That would expand any air bubbles or encourage air dissolved in brake fluid to create new bubbles. (Doesn't seem that it should be all that different than any other R1200 model where they go up over the tank from the routing up the fork- but I don't service any R1200R's so don't know)

    Seen a few track cages with this sort of problem where some teams have gone to extreme of heating brake fluid to drive out dissolved gases before filling a system. Others (more commonly) just end up bleeding these things after every track session...
    The lines all run under the tank on an R.. unlike our plastic covered brethren - the R tank is the exterior of the bike (and damn good looking too!) It's possible they get warmer under the tank (where the ABS modulator also lives.)

    I haven't noted a heat relationship with the lever pull, but I'll have to note it and see if it appears. Today the lever was nice and firm - and it was about 50F out.
    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

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