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Bleedin' brakes!

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    Bleedin' brakes!

    Been working on the brakes. I wasn't having any trouble with them, but wanted to add stainless lines and to replace the rubber bits in the caliper.

    So far:

    Cleaned and rebuilt the caliper
    Pulled the MC off and cleaned it

    I've read the threads:

    1. Did the squeeze, open, close release dance--no joy
    2. Pulled out the Mighty Vac and cranked it up--same result

    I can't get the brake lever to stiffen up. Much softer than it was with the old rubber line and old rubber parts.

    It is sitting out in the garage with the lever pulled back and tied down. Hoping that trick will let the air bleed, but seems like a last resort.

    Any thoughts as to what I ought to do next?

    #2
    keep pumping, fresh lines take forever to fill. I usally fill the calipers before I start.

    Comment


      #3
      So far I've run entire bottle of DOT 4 through it. Any thoughts on how much it ought to take?

      Comment


        #4
        Entire bottle should do all the brakes and have left overs. Still got some air someplace I would say. Did you use new crush washers on the banjos bolts?
        MY BIKES..1977 GS 750 B, 1978 GS 1000 C (X2)
        1978 GS 1000 E, 1979 GS 1000 S, 1973 Yamaha TX 750, 1977 Kawasaki KZ 650B1, 1975 Honda GL1000 Goldwing, 1983 CB 650SC Nighthawk, 1972 Honda CB 350K4, 74 Honda CB550

        NEVER SNEAK UP ON A SLEEPING DOG..NOT EVEN YOUR OWN.


        I would rather trust my bike to a "QUACK" that KNOWS how to fix it rather than a book worm that THINKS HE KNOWS how to fix it.

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          #5
          Yes, new crush washers. No apparent leaks anywhere.

          Comment


            #6
            Maybe it is your master cylinder. Did you hose it out with some sort of solvent?

            Solvent, even brake cleaner will sometimes distort the rubber seals.

            If your not getting air with your vac pump I would think the problem is the master cylinder. If fluid is escaping around the seals inside the master cylinder it will not build pressure.

            I am an automotive mechanic and have seen on several occasions if the brake system goes dry due to a leak the master cylinder will not build as much pressure when refilled. Usually its because someone has been letting it leak and adding fluid until they get it fixed.

            Sounds like you did it all correctly and if there are no leaks at the caliper banjos or master thats the only other thing it could be.

            I always let gravity do the work for me. Put a small rubber hose onto the bleeder, crack the bleeder open, have a few pops and check it.

            Comment


              #7
              Did you prime the MC before hooking up the lines?
              Did you clean the bleeder-nipples before attaching a might-vac to them?

              If your bleeders are clogged, rusted or loosened too much, you can end up pulling outside air threw the threads, instead of sucking air out of the lines.

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                #8
                Well, that could be the issue. I did spray the MC down with brake cleaner.

                With the top off the MC the second hole shoots fluid into the air quite nicely.

                I am getting air with the vacuum pump and I think the hose is tight around bleeder nipple. Can get to 20 psi vacuum and the needle drops only very slightly on the pressure gauge.

                Comment


                  #9
                  Originally posted by 1_v8_merc View Post
                  Did you prime the MC before hooking up the lines?
                  Did you clean the bleeder-nipples before attaching a might-vac to them?

                  If your bleeders are clogged, rusted or loosened too much, you can end up pulling outside air threw the threads, instead of sucking air out of the lines.
                  I did not prime the MC before hooking up lines. Didn't see any mention of that process in the procedures, but perhaps I read too quickly.

                  Could be the bleeder threads are too loose. Saw Ed's (?) suggestion to put teflon tape on the threads after I had filled the system.

                  Comment


                    #10
                    If it was me, I would take out the bleeder nipples, be sure they are clear, then use some anti seize or teflon tape on the threads to help seal them. Air will get sucked down the threads most times. Then I would pump the mighty vac till the suction guages is almost pegged and crack the nipples open ..WAY OPEN and shut before the guage is all the way down. I find that if you do the way open method a few times it really sucks a lot of the air out of the lines faster and easier. Then tie back the handle overnight.
                    MY BIKES..1977 GS 750 B, 1978 GS 1000 C (X2)
                    1978 GS 1000 E, 1979 GS 1000 S, 1973 Yamaha TX 750, 1977 Kawasaki KZ 650B1, 1975 Honda GL1000 Goldwing, 1983 CB 650SC Nighthawk, 1972 Honda CB 350K4, 74 Honda CB550

                    NEVER SNEAK UP ON A SLEEPING DOG..NOT EVEN YOUR OWN.


                    I would rather trust my bike to a "QUACK" that KNOWS how to fix it rather than a book worm that THINKS HE KNOWS how to fix it.

                    Comment


                      #11
                      I 'm telling ya this is not uncommon with fresh dry lines...keep going

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                        #12
                        Well, I'm gonna call it for tonight. I'll let it set overnight and get back to it after work tomorrow.

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                          #13
                          Absolutely use ant seize or tape on the bleeder threads. Even Vasoline or wheel bearing grease.

                          Comment


                            #14
                            I had the same problem with my mity vac, until I wrapped the the bleeder threads with plumbers tape. Cost me a second can of brake fluid, but lesson learned.
                            Old age and treachery will beat youth and skill every time1983 GS 750
                            https://c1.staticflickr.com/5/4256/3...8bf549ee_t.jpghttps://c1.staticflickr.com/5/4196/3...cab9f62d_t.jpg

                            Comment


                              #15
                              Sounds like good advice. I did get better results today after strapping the brake lever down overnight. Better...but not great. no brakes until the lever is halfway back....strong then...but not right.

                              Soon had a track meet tonight...so no work tonight.

                              Will update later.

                              Comment

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