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    Brake drags

    Front brakes on the 78 1000 started dragging and i had to pull over and loosen the banjo bolt at the master cylinder and they released as expected. So i took the master apart thinking something had plugged the return port....poked it out and blew air through it. Reassembled and went a mile and i could feel them start again so i used back brake only and got it to the shop. Sure enough the rotors were pretty warm and the bike was a bit hard to push.

    I thought that since the release of pressure when i loosened the banjo bolt it was telling me fluid wasnt returning...which in turn screamed return port problem. But nope. Ive never had this particular problem. Looking for leads please as to whats holding back fluid. New brake lines made by the same place i always get them made at...im stumped.
    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.

    #2
    Since the brakes released by cracking the banjo up at the master cylinder it tells me the problems with the master itself. But the return ports not blocked, so this is why im puzzled as to whats preventing line pressure from being released and causing the pads to drag. Then heat takes over and the brakes get tighter and tighter.
    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


      #3
      I have seen issues with rebuild kits for the master (plunger length).
      Have you rebuilt it ?

      Would be interested if you can see fluid returning when pressing the pistons into the caliper.
      Rijk

      Top 10 Newbie Mistakes thread

      CV Carb rebuild tutorial
      VM Carb rebuild tutorial
      Bikecliff's website
      The Stator Papers

      "The thing about freedom - it's never free"

      Comment


        #4
        Yes...new kit installed. I was actually just thinking this very thing too. Must be a sign...lol

        Its the 16mm bore. Kit came from Dime City. They bought up Z1 from what i gather.
        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


          #5
          Just a thought on the rebuild kit. IF i poke into the return port with the piston installed and it blocked by the rubber seal can i drill an auxillary port to allow pressure relief?. Im thinking add a small hole with a micro drill bit a little bit more toward the brake line??? Think this is a plausible solution?
          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


            #6
            guess that would work.
            But if you have it apart anyway, personally i would compare the plungers (that is, if you still have the old one)
            Thing is, the plungers usually don't wear out i hardly ever replace them.
            The plunger wears a recess in the master and then it starts bleeding past the seal.
            If the seal is old and lost some flexibility. New seal on old plunger usually works a treat.
            Last edited by Rijko; 08-02-2020, 04:43 PM.
            Rijk

            Top 10 Newbie Mistakes thread

            CV Carb rebuild tutorial
            VM Carb rebuild tutorial
            Bikecliff's website
            The Stator Papers

            "The thing about freedom - it's never free"

            Comment


              #7
              Threw old one out and i dont have another body to try out. All it needs is to release the line pressure and alls well. Im betting youre on track about the rebuild kit. Ill swing by the shop after work tomorrow and poke a fine wire into the return port. I bet it hits that rubber seal on the handle end of the piston. If it does i got micro bits and can relocate a bleeder hole easily enough. Sure cant hurt anything.
              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


                #8
                K&L strikes again.
                Ed

                To measure is to know.

                Mikuni O-ring Kits For Sale...https://www.thegsresources.com/_foru...ts#post1703182

                Top Newbie Mistakes thread...http://www.thegsresources.com/_forum...d.php?t=171846

                Carb rebuild tutorial...https://gsarchive.bwringer.com/mtsac...d_Tutorial.pdf

                KZ750E Rebuild Thread...http://www.thegsresources.com/_forum...0-Resurrection

                Comment


                  #9
                  Actually its an ALL BALLS kit.

                  RIJKO...you are the winner. wire hit the rubber cup thing when i tried sticking it through. Squeezed the lever to move the cup and wire passed through. I drilled a hole about 1/8 inch toward the banjo bolt end and rode it around the block a dozen times jacking the brakes to heat them up. Must have applied brakes 200 times and no fails. Done.
                  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


                    #10
                    Glad you got it working Chuck !
                    Rijk

                    Top 10 Newbie Mistakes thread

                    CV Carb rebuild tutorial
                    VM Carb rebuild tutorial
                    Bikecliff's website
                    The Stator Papers

                    "The thing about freedom - it's never free"

                    Comment


                      #11
                      Did you notice that you had to move the lever more before you got braking pressure?

                      Personally, I think I would have shaved a bit off the lever end of the pistone to let it retract just a bit more.

                      .
                      sigpic
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                      Comment


                        #12
                        Yes on lever pull Steve. The end of the piston at the lever is irrelivent. The piston contacts the circlip as it's stop point. In any case I'll source a true known 78 1000 master at some point and replace it.
                        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


                          #13
                          I had a brake line fail internally on a car. It acted like a check valve,and would make the right front drag. Thought it was a seized caliper. I had heard of that, but I had never experienced it.

                          Glad you sorted it out.
                          sigpic Too old, too many bikes, too many cars, too many things

                          Comment


                            #14
                            I've had that happen several times on vehicles, including the rear line on a Chinesium 4 wheeler. The line will collapse internally. Pressure from the master will push thru it but it can't return. When the bleeder lets the pressure off it's my 1st suspect.

                            Comment

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