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Front brake problems

Discussion in 'General R1200RS Discussions' started by folagana, Aug 17, 2017.

  1. m1bjr

    m1bjr Member

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    If you are bleeding after the alpine work, you over cooked the fluid...
    RBF600 does well on my track cars. Much higher boiling point and lasts just fine needing no special treatment or regime.
     
  2. folagana

    folagana Well-Known Member Contributor

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    Yesterday I finished the 30.000 service activities on my RS.

    I did also the front and rear brake oil change by using GS911 wifi tool to bleed also the ABS pump. I cleaned (as Richard suggested) the caliper cyclinders.

    Some cylinders were not moving easily others yes. In my experience/opinion there aren't blocked cylinders or really damaged.

    At the end of the job the brake is worser a bit. The lever stroke is a bit longer and it is still spongy.

    Surfing on internet, I found on a GS forum (which has the same brake pump) a lot of users watercooled head GS which are not happy (like me) with the front brake.

    I understood the front pump is from magura and now BMW started a lawsuit against magura. So, I do suspect the pump quality is not good enough.......
     
  3. folagana

    folagana Well-Known Member Contributor

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    Finally I found the problem. Not easy!
    I was wrong, the pistons are not moving correctly 3 of 4 are a bit sticky on the left side (right side not yet checked).

    I'll try to clean them again and to put a lubrificant to improve the movement. I hope it will help.

    Looking to the pistons I don't know if they can be turned easily, do you have some suggestion?

    I also found an additional screw to bleed the caliper (I do suppose)
    $_57.JPG
     
    Last edited: Sep 12, 2017
  4. Stef

    Stef Member

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    The front brake system is, due to its integration with the rear brake system and the ABS complicated enough to have it maintained by a professional, such as a BMW dealer. When I see all different comments I can only conclude that no-one apparently really knows the system thoroughly.
     
  5. folagana

    folagana Well-Known Member Contributor

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    On monday, I have bring the bike to the dealer to check the brakes. I complained of the long stroke and the soft and spongy brake response.

    The professional BMW dealer say: "it is normal";
    Me: "Sure? I never driven a bike with such kind of brakes";
    BMW: "yes, we know but we assure you, it is normal";

    Unfortunately I'm an engineer then I don't believe to the fables
     
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  6. Richard230

    Richard230 Well-Known Member Contributor

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    If brake caliper pistons can be turned, I have never heard anyone say so, or read any article that even mentioned the possibility.

    If you removed the pistons, I imagine that you could polish them with some sort of emery paper, or the like. I know that calipers can be completely rebuilt, but doing so would probably be best left to a specialist who has a proven track record. Plus, you probably will need new piston seals as the old ones might be damaged when the pistons are removed. Maybe an attempt to find a video showing how brake calipers are rebuilt (if there is such a thing) would be worthwhile checking out. The more knowledge and information you have the better you know what to do - or, if someone else is doing the work, you will have some sense if they are doing it correctly.
     
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  7. folagana

    folagana Well-Known Member Contributor

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    Folks

    I fixed 80/90 % of the problem. I cleaned the (left only) caliper and put a silicone spray on all pistons (compatible with the seal rubber) to lubrificate and the stroke now is definetely better and the brake engage is now like a new bike (no soft or spongy).

    next step, continue the job on the right caliper



    I 've gotten a lot of info on the GS forum (our calipers are the same of the GS), like some car calipers ours must be turned to be removed and there are some special tools to do it. On the DVD-ROM this kind of job is not reported because Brembo do not allow BMW dealer to do the job, also the dealer must send to brembo or approved affiliate, the calipers to be rebuilted.

    I didn't turn them yet, but it is not necessary any more

    You are right, removing the piston is a job to be done by a specialist. Even if it is not complicated (I saw a lot of video on internet) the BMW caliper are a bit different from tokina or others and as I said they need some tools and the seal kit cost about 100€ per caliper.
     
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