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Trouble adding Brake Fluid to System after Rebuild

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  • Trouble adding Brake Fluid to System after Rebuild

    I stripped apart my master cylinder and replaced the parts with a rebuild kit, cleaned the lines and than installed the parts. A while back I removed the disc brakes and replaced the pads. I purchased a vacuum pump from NAPA to draw the fluid through the system. I loosened the bleeding nipple with a tube attached to the vacuum and began drawing fluid through the system. Fluid moves through but mixed with air and the bubbles never bleed out. All along I am adding fluid to the master cylinder keeping the level above the bottom. Am I missing something? Perhaps I am loosening the nipple too much and allowing air to flow in through the thread? The vacuum level on the device says that there is pressure during the process. I have bleed almost an entire bottle of fluid through the system and don't want to try again until I figure this out. Any help would be greatly appreciated. Cheers, Doug
    81H Venture - hope to ride summer 2013
    79F Cafe Racer at Some Point;
    68 CB175 Sloper - Cafe Racer
    74 KZ400 - Restoration project nightmare
    62 BSA Super Rocket - In Pieces
    72 CB100 Super Sport - Not super or sporty but fun

  • #2
    The air bubbles you are seeing are most likely being sucked thru the threads of the bleeder screw. If you sucked a bunch of fluid thru, you probably got all the air out of the system and I would ignore those bubbles. If you really want to be sure, wrap teflon tape around the threads of the bleeder screw.
    2H7 (79) owned since '89
    3H3 owned since '06

    "If it ain't broke, modify it"

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    • #3
      Originally posted by bikerphil View Post
      ...wrap teflon tape around the threads of the bleeder screw.
      A big +1 on that. That will not only eliminate the bubbles you're seeing, but make bleeding go faster.
      Fast, Cheap, Reliable... Pick any two

      '78E original owner - resto project
      '78E ???? owner - Modder project FJ forks, 4-piston calipers F/R, 160/80-16 rear tire
      '82 XJ rebuild project
      '80SG restified, red SOLD
      '79F parts...
      '81H more parts...

      Other current bikes:
      '93 XL1200 Anniversary Sportster 85RWHP
      '86 XL883/1200 Chopper
      '82 XL1000 w/1450cc Buell, Baker 6-speed, in-progress project
      Cage: '13 Mustang GT/CS with a few 'custom' touches
      Yep, can't leave nuthin' alone...

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      • #4
        I've had this problem too, and I've never thought about teflon tape. Good tip!
        79 F

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        • #5
          Ok - thanks. I tested the lever and the brakes appear to hold firm. However, I noticed than the new pads rub on the discs. Can I assume that the pads will wear down/break in after a short ride?
          81H Venture - hope to ride summer 2013
          79F Cafe Racer at Some Point;
          68 CB175 Sloper - Cafe Racer
          74 KZ400 - Restoration project nightmare
          62 BSA Super Rocket - In Pieces
          72 CB100 Super Sport - Not super or sporty but fun

          Comment


          • #6
            A small amount of rubbing can be normal. Yes, you'll need to 'bed' the pads and wear a few high spots off, but as long as the wheel will turn freely it's good.
            Last edited by crazy steve; 05-27-2013, 09:17 PM.
            Fast, Cheap, Reliable... Pick any two

            '78E original owner - resto project
            '78E ???? owner - Modder project FJ forks, 4-piston calipers F/R, 160/80-16 rear tire
            '82 XJ rebuild project
            '80SG restified, red SOLD
            '79F parts...
            '81H more parts...

            Other current bikes:
            '93 XL1200 Anniversary Sportster 85RWHP
            '86 XL883/1200 Chopper
            '82 XL1000 w/1450cc Buell, Baker 6-speed, in-progress project
            Cage: '13 Mustang GT/CS with a few 'custom' touches
            Yep, can't leave nuthin' alone...

            Comment


            • #7
              It almost sounds like rubber rubbing but I cannot find any tire contact points. The wheel turns but there is good resistance at this point.
              81H Venture - hope to ride summer 2013
              79F Cafe Racer at Some Point;
              68 CB175 Sloper - Cafe Racer
              74 KZ400 - Restoration project nightmare
              62 BSA Super Rocket - In Pieces
              72 CB100 Super Sport - Not super or sporty but fun

              Comment


              • #8
                Generally speaking, you won't get more than three turns out the front wheel with everything installed and giving it a good spin. Anything over one turn is usually ok.
                Fast, Cheap, Reliable... Pick any two

                '78E original owner - resto project
                '78E ???? owner - Modder project FJ forks, 4-piston calipers F/R, 160/80-16 rear tire
                '82 XJ rebuild project
                '80SG restified, red SOLD
                '79F parts...
                '81H more parts...

                Other current bikes:
                '93 XL1200 Anniversary Sportster 85RWHP
                '86 XL883/1200 Chopper
                '82 XL1000 w/1450cc Buell, Baker 6-speed, in-progress project
                Cage: '13 Mustang GT/CS with a few 'custom' touches
                Yep, can't leave nuthin' alone...

                Comment


                • #9
                  I've found that greasing the threads works better than tape. I use disk brake grease from Permatex, because it won't contaminate the brake fluid. A generous smear and no bubbles.

                  Comment


                  • #10
                    Brake grease is a great idea and I will give it a shot. Thanks.
                    81H Venture - hope to ride summer 2013
                    79F Cafe Racer at Some Point;
                    68 CB175 Sloper - Cafe Racer
                    74 KZ400 - Restoration project nightmare
                    62 BSA Super Rocket - In Pieces
                    72 CB100 Super Sport - Not super or sporty but fun

                    Comment


                    • #11
                      Originally posted by mmatches1 View Post
                      Brake grease is a great idea and I will give it a shot. Thanks.
                      Well I used teflon tape yesterday and it worked a treat, along with my mightyvac on the rear brake system. Doing the fronts right now!
                      Bone stock 1980 Special except for the exhaust and crashbars. Oh yeah, and the scabbard for the Winchester Defender.

                      Comment


                      • #12
                        Teflon tape won't attract dust/dirt.....
                        Fast, Cheap, Reliable... Pick any two

                        '78E original owner - resto project
                        '78E ???? owner - Modder project FJ forks, 4-piston calipers F/R, 160/80-16 rear tire
                        '82 XJ rebuild project
                        '80SG restified, red SOLD
                        '79F parts...
                        '81H more parts...

                        Other current bikes:
                        '93 XL1200 Anniversary Sportster 85RWHP
                        '86 XL883/1200 Chopper
                        '82 XL1000 w/1450cc Buell, Baker 6-speed, in-progress project
                        Cage: '13 Mustang GT/CS with a few 'custom' touches
                        Yep, can't leave nuthin' alone...

                        Comment

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