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Thread: 1990 R 100 GSPD front brake master cyl bleeding

  1. #1
    not lost til out of gas 128521's Avatar
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    1990 R 100 GSPD front brake master cyl bleeding

    morning all, I had to rebuild my brake caliper, when I took it apart I let the brake line dangle and the fluid dribbled out. now that I put it back together I can't get the master cyl to pump. my Clymer manual says to bleed the master cyl first then each union. all I get is a little pressure at the end of the master cyl, then nothing. any suggestions would be appreciated
    don't know where I'm going, but I'm making good time. 1990 R 100 GSPD, 2005 R 1200 GS

  2. #2
    Administrator 20774's Avatar
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    I don't have any experience with dual front brakes. But general things to consider would be to try the method of sucking the fluid out of the bleed valves. You may need to pull the hand lever down about half way and tie it off, leaving it that way over night. This can help to let air bubble up.

    Hopefully, the seal in the master cylinder isn't ripped. When bleeding, it's a good idea to not pull the lever through the full range of motion, but rather to move it over the normal range you would use during braking. That way, the piston seal is traveling over previously swept areas of the bore. Much more than that leads to the possibility that the seal will encountered hidden rust, thus tearing the seal.
    Kurt -- Forum Administrator ---> Resources and Links Thread <---
    '78 R100/7 & '69 R69S & '52 R25/2
    mine-ineye-deatheah-pielayah-jooa-kalayus. oolah-minane-hay-meeriah-kal-oyus-algay-a-thaykin', buddy!

  3. #3
    not lost til out of gas 128521's Avatar
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    morning all, operator error, when I installed the piston in the caliper I nicked the seal. I finally went and bought a hand pump to bleed the brake , which worked really good. once I had pressure fluid gushed out of the bad seal, so I removed it and reinstalled one of the old ones. no leaks and the brakes work great. I took apart the master cyl just to inspect it, it looked good so I put it back together. I guess the problem, other than the bad seal, was the master cyl is so small it has a hard time filling a new system. anyway the hand bleeder made short work of that, I should have got one of those a long time ago. thanks
    don't know where I'm going, but I'm making good time. 1990 R 100 GSPD, 2005 R 1200 GS

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