Rear brake master cylinder

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  • Guest

    #1

    Rear brake master cylinder

    Well, guess it's time to rebuild the rear master. Not able to keep pressure up on the system. At first thought it was an air bubble, so bled it out and seemed to be fine. Nice solid pedal. Went for a ride yesterday and it slowly started losing pressure again. Pretty good for 40 years worth. Kit ordered.
  • salty_monk
    Forum LongTimer
    GSResource Superstar
    Past Site Supporter
    Super Site Supporter
    • Oct 2006
    • 14003
    • London, UK to Redondo Beach, California

    #2
    Mine was passed rebuild... I had good luck adapting an EX300 one.
    1980 GS1000G - Sold
    1978 GS1000E - Finished!
    1980 GS550E - Fixed & given to a friend
    1983 GS750ES Special - Sold
    2009 KLR 650 - Sold - gone to TX!
    1982 GS1100G - Rebuilt and finished. - Sold
    2009 TE610 - Dual Sporting around dreaming of Dakar..... - FOR SALE!

    www.parasiticsanalytics.com

    TWINPOT BRAKE UPGRADE LINKY: http://www.thegsresources.com/_forum...e-on-78-Skunk/

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    • GSXR7ED
      Forum LongTimer
      Past Site Supporter
      • Dec 2012
      • 10147
      • DE via L.A.

      #3
      Hey Bill!

      You gonna post pics?

      Glad you're keeping well.

      Ed
      GS750TZ V&H/4-1, Progressive Shocks, Rebuilt MC/braided line, Tarozzi Stabilizer[Seq#2312]
      GS750TZ Parts Bike [Seq#6036]
      GSX-R750Y (Sold)

      my opinion shouldn't be taken as gospel or in any way that would lead you to believe otherwise (30Sep2021)

      Comment

      • Guest

        #4
        Originally posted by salty_monk
        Mine was passed rebuild... I had good luck adapting an EX300 one.
        It hadn't leaked any fluid so I'm think the rubber piston just finally gave out.

        Comment

        • Guest

          #5
          Originally posted by GSXR7ED
          Hey Bill!

          You gonna post pics?

          Glad you're keeping well.

          Ed
          Hey Mr Ed I had to get the Suzi out and ride it, felt good except for the rear brake. Beth took the Spyder. She said she could hear the bike any time I jumped on the throttle. Ride felt good, knee didn't complain either lol. Uh you get started yet lol. Guess I could post a pic or two.

          Comment

          • GSXR7ED
            Forum LongTimer
            Past Site Supporter
            • Dec 2012
            • 10147
            • DE via L.A.

            #6
            Originally posted by mrbill5491
            Hey Mr Ed I had to get the Suzi out and ride it, felt good except for the rear brake. Beth took the Spyder. She said she could hear the bike any time I jumped on the throttle. Ride felt good, knee didn't complain either lol. Uh you get started yet lol. Guess I could post a pic or two.
            MrBill,

            I still remember our adventure rides through southern NM...good memories!

            Loud pipes...eh? They save lives you know...lol.

            Yeah, post pics when you can.

            Yes, I will be starting soon...been kicking the tires on my "T" and looking at the work that lays ahead.

            Glad your knees are holding up. My knees are strong enough to move and hold my bike. I have parts scattered in several boxes in the garage and attic.

            See you around.

            Ed

            *****
            GS750TZ V&H/4-1, Progressive Shocks, Rebuilt MC/braided line, Tarozzi Stabilizer[Seq#2312]
            GS750TZ Parts Bike [Seq#6036]
            GSX-R750Y (Sold)

            my opinion shouldn't be taken as gospel or in any way that would lead you to believe otherwise (30Sep2021)

            Comment

            • Guest

              #7
              Originally posted by GSXR7ED
              MrBill,

              I still remember our adventure rides through southern NM...good memories!

              Loud pipes...eh? They save lives you know...lol.

              Yeah, post pics when you can.

              Yes, I will be starting soon...been kicking the tires on my "T" and looking at the work that lays ahead.

              Glad your knees are holding up. My knees are strong enough to move and hold my bike. I have parts scattered in several boxes in the garage and attic.

              See you around.

              Ed

              *****
              Lol, I'm wanting to change the exhaust on the Spyder, wifey says no. But but honey it would sound so cool...Hmmm maybe I can surprise her when she goes off for her 6 week training? Heheheh.

              Comment

              • mustangflyr
                Forum Mentor
                • Oct 2004
                • 308
                • Green Cove Springs , FL

                #8
                You could have it sleeved, that will fix it .
                1980 GS1000E

                Comment

                • Guest

                  #9
                  Originally posted by mustangflyr
                  You could have it sleeved, that will fix it .
                  Have what sleeved? The rear master cylinder? Pretty sure it's just the piston. After 40 years, I think I would get a bit worn too.

                  Comment

                  • gs11ezrydr
                    Forum Mentor
                    • Mar 2013
                    • 407
                    • South Central Kentucky

                    #10
                    Stainless steel re-sleeving is an option,If the bore is out of round or worn.I have seen ads in the magazine Classic Motorcycle Mechanics for the service to brake master cylinders,Calipers.They service Motorcycles,Cars,and Commercial vehicles.Mostly for restoration purposes.I don't know of any in the U.S. The company in the UK is Past Parts Unlimited. restore@pastparts.co.uk My browser couldn't connect ??? I have considered this service when parts were either not available and discontinued as a lot of our older bikes fall into this category.Down side all I have is an address TEL.# and FAX # So somebody out there is doing it in the U.S. if there is a market for it.Surely. I have subscribed for a few years at www.classicmechanics.com
                    Last edited by gs11ezrydr; 02-14-2020, 10:57 PM.
                    sigpic 82 gs1100ez 1168 Wiseco,Web .348 Cams,Falicon Sprockets,Star Racing Ported Head,1mm o/s Stainless Valves,APE Springs,Bronze Guides,etc.APE Billet Tensioner,36CV Carbs,Stage 3 Dynojet,Plenum w/K&N filter,Trued,Welded,Balanced,Crank w/Katana rods & Billet left end, FBG backcut trans, VHR HD Clutch basket,APE nut,VHR High volume oil pump gears,1150 Oil cooler,V&H Megaphone header w/Competition baffle,Dyna S,Coils,Wires,etc.Other misc.mods.

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                    • Guest

                      #11
                      Well, got started on my rear master rebuild. Took it apart last night and was pleasantly surprise. It was fairly clean inside, cylinder itself was fine, no scratches or anything. The rubber pistons show some wear but hell, what'cha expect for 40 years old.

                      DSCN1239.jpg

                      Comment

                      • GSXR7ED
                        Forum LongTimer
                        Past Site Supporter
                        • Dec 2012
                        • 10147
                        • DE via L.A.

                        #12
                        That's not bad looking at all, Bill.

                        Compared to my front MC rebuild...anyway.

                        Thanks for posting pic.

                        Ed

                        ****
                        GS750TZ V&H/4-1, Progressive Shocks, Rebuilt MC/braided line, Tarozzi Stabilizer[Seq#2312]
                        GS750TZ Parts Bike [Seq#6036]
                        GSX-R750Y (Sold)

                        my opinion shouldn't be taken as gospel or in any way that would lead you to believe otherwise (30Sep2021)

                        Comment

                        • Guest

                          #13
                          Did a comparison last night between the old parts and new stuff for the rear master. Old stuff slid back and forth without hardly any resistance. New stuff, you could feel the difference, the rubber parts sealed up nicely.

                          Comment

                          • Guest

                            #14
                            Originally posted by GSXR7ED
                            That's not bad looking at all, Bill.

                            Compared to my front MC rebuild...anyway.

                            Thanks for posting pic.

                            Ed

                            ****
                            I may just do the front MC as well just for chits and giggles. It does have 40 years of wear on it. Some preventive maintenance.

                            Comment

                            • Guest

                              #15
                              Rear MC is back on and have very nice rear brakes again.

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