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Brake bleeding

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  • Brake bleeding

    I am having a devil of a time getting pressure into the new system
    (new lines, rebuild calipers, new master cylinder.)
    What is the deal?
    I can pump fluid out, I have reverse bled, I have even put the old
    MC on.. nothing.. the lever stays soft as a grape..
    Before I have to go though $25 in fluid what am I doing wrong?
    Is there a right way to refill a system?

  • #2
    front or rear? are you sure you do not have a leak anywhere?
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    • #3
      You probably have air in the master cylinder. Bleed the master by pumping it up and breaking the banjo loose.

      Unless you have a bleeder on the master, but I don't think the Kats do.
      I like you. When the world is mine your death will be quick and painless.


      • #4
        zleviticus Fronts..
        Fluid is moving..
        I don't see any leaks.
        The pistons wiggle but don't extend, I pulled the
        front wheel to get at the bleeders better.
        (I've got steel blocks in the calipers)

        Wingspan I'll give it a try..
        Hell at this point I give anything a try.


        • #5
          SpeedBleeders (grins)...

          KNOW THIS:
          The cross-bar that distributes the brake fluid between the left and right front calipers can trap air. Bleed on the side-stand when doing the left side.

          Sometimes an old trick will help: wrap a couple rubber bands over the grip so they hold the brake MC piston open. Air may travel to the top of the system overnight. Park on the sidestand at that time, so the cross-bar (tube) is slanted uphill towards the master cylinder.

          It is not uncommon to require as many as 60 pumps per side to get all the air out of a system. It's really a two person job, or use speedbleeders or a brake fluid pump (Mity-Vac). If you do it by yourself, while you have the bleeders closed and are refilling the reservior, air can start traveling upwards again, defeating the pumping you were doing to push it out the bottom.

          Putting a length of tubing on the bleeder and leading it to a fluid container that has enough brake fluid to cover the hose will keep it from sucking air back up into the system. You can leave the bleeder open and just keep pumping your heart out while continuously refilling the system from the top.

          MC piston seals do go bad. If nothing else works, replace it.

          More brake bleeding tips in the upcoming book

          =-= The CyberPoet
          Remember The CyberPoet


          • #6
            I was going to suggest a zip tie but Cyber is full of information!
            TDA Racing/Motorsports
            1982 Honda CB750 Nighthawk, 1978 Suzuki GS750 1986 Honda CBR600 Hurricane; 1978 Suzuki GS1100E; 1982 Honda CB750F supersport, 1993 Suzuki Katana GSX750FP. 1981 Suzuki GS1100E (heavily Modified)
            Who knows what is next?
            Builder of the KOTM Mreedohio september winning chrome project. I consider this one to be one of my bikes also!
            Please look at this build!


            • #7
              Cyber: Thanks,
              Know this: LOL couldn't resist..
              *I have Goodridge 2 line system on,
              no cross bar

              *I always use a jar and the shorest line I can
              (to create a fluid seal) dad tought me this in the '70s, though I am likeing another system.
              (pic woth 1000 words will post soon)

              *60 pumps I bet I'm up to 120 by now.
              I have a feeling I have a bunch of air caught in the
              calipers. I have reverse bled though each bleeder about 10 cc of fluid. I am doubtfull its the lines.
              After that much fluid it must be trapped in a dead leg. Though the design is supposed to prevent that.


              • #8
                B_P, tell me when you get it figured out as I am planning the same work in the near future.
                AMA member # 224227


                • #9
                  Originally posted by Black_peter
                  *60 pumps I bet I'm up to 120 by now.
                  I have a feeling I have a bunch of air caught in the
                  calipers. I have reverse bled though each bleeder about 10 cc of fluid. I am doubtfull its the lines. After that much fluid it must be trapped in a dead leg. Though the design is supposed to prevent that.
                  The design of the caliper can leave air trapped in it if the parking surface isn't flat, or the fluid moving through isn't moving quickly enough during the pumping (particularly in the rear caliper design).

                  Q: If you close off the bleeders and pump, do you get pressure build-up, and will you find any sources of leaks?

                  Q: Did you try the rubber-band trick overnight?

                  =-= The CyberPoet
                  Remember The CyberPoet


                  • #10
                    cyber You are right!! You would think they would have designed the caliper so that you bled oposite of the inlet, I find that odd..
                    Anywhoo Here is what I did:

                    I got the "new" GSXR MC, filled the piston with fluid,
                    and as I tightened the banjos I gave it a little squeeze. Bingo I have pressure. Now instead of my usual bleeding rig (jar and line) I used a 10cc syringe connected with a small line to the bleeder.
                    (I had a couple of cc's of fluid in it) Next as I loosened the bleeder I pulled on the plunger.
                    I drew any air in the line up and then fluid from the caliper. a few squeezes of the lever and I was rewarded with air.. I think I will use this method from now on. The air goes right to the top and
                    you have the option of pumping the lever or drawing with the syringe. Plus the volume of line is so small the "fluid valve" is very efficiant.
                    I could see even removing the plunger and removing excess fluid for a long bleeding session.
                    Sorry I don't have faith in SpeedBleeders, just one of those things I guess..

                    I think Wingspan had it right with "air trapped in the master cylinder"
                    So Meikol2 stock up on fluid. I strongly recommend getting some syringes, at the very least they are handy for filling the lines..


                    • #11
                      Thanks all.
                      AMA member # 224227


                      • #12
                        Meikol2 If you are rebuilding your calipers;
                        I found the whole process a piece of cake but worth
                        Get some gloves, brake fluid is nasty stuff and you will be getting it all over you during a rebuild.
                        A few tooth brushes will come in handy.
                        Make sure you get the seals that go between the caliper halves. (Item #2 in the Bike bandit microfich) I was not prepared for the amount of gunk built up in the calipers. Expect to spend some time cleaning the seal grooves. These cannot be scratched so it take a while to clean them.
                        (compressed air would have helped a lot!!)
                        Re-assembly was easy-peasey.
                        The bolts holding the caliper halves together was a pain to bust. As was the AN type fitting on the caliper (I only removed these because I was adding SS lines) I used BLUE Loctite on the caliper bolts, blue is removable. Red is perminent. (in the Loctite brandname world!!)
                        Lube the seals and pistons with clean fluid.
                        Every thing poped together.
                        I had both re-assembled in 30 mins..


                        • #13
                          Good points, thanks alot. It always helps to have somebody's first-hand knowledge.

                          And good job!
                          AMA member # 224227


                          • #14
                            Oh, one more thing..
                            If you don't have compressed air, (I don't)
                            getting the pistons out can be a pain.
                            I pumped them out as far as a I could
                            (I removed the system in one piece)
                            but natually the loose pistons came out and the tough ones stuck #-o
                            So heres a trick:
                            I used a pair of channel locks..
                            I put one jaw inside the piston cup,
                            the other on the caliper body, I was able to lever the piston out with out grabbing the outside, the out side works against the seal so I would advise against using any tool on it..


                            • #15
                              Originally posted by Black_peter
                              Oh, one more thing..
                              If you don't have compressed air, (I don't)
                              getting the pistons out can be a pain.
                              I have a different trick I use:
                              $12 bicycle foot pump from Walmart (same one I use for my tires), put the cone nozzle on it and then slip a vacuum plug (the type used to cover carb vacuum fittings when not in use) over the end and snip off the tip. Fits right into the hose fitting of the caliper, lets you apply pressurized air on demand

                              =-= The CyberPoet
                              Remember The CyberPoet