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    #31
    There are other alternatives to rebuilding stock brakes... I guess you're so far into these now you may not want to change direction

    If these are original brake lines I would change them regardless of whether they are causing this issue or not - at that age they are an issue!

    Those original 78 model year brakes are pretty pathetic to be honest. Later models are much better.
    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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      #32
      Originally posted by salty_monk View Post
      If these are original brake lines I would change them regardless of whether they are causing this issue or not - at that age they are an issue!.
      As I recall, owner's manual says change original (rubber) lines every two years!
      1982 GS1100E V&H "SS" exhaust, APE pods, 1150 oil cooler, 140 speedo, 99.3 rear wheel HP, black engine, '83 red

      2016 XL883L sigpic Two-tone blue and white. Almost 42 hp! Status: destroyed, now owned by the insurance company. The hole in my memory starts an hour before the accident and ends 24 hours after.

      Comment


        #33
        Wow, you guys here are all awesome! Thank you very much for all the input! It's been 110F degrees in the carport the past few days so I've only been working short periods of time out there. I'm on it.
        1978 Suzuki GS 750 EC

        Comment


          #34
          I'd put a hard stop on the proceedings and change the brake lines. I'm doubtful that's the problem but they should be changed regardless. Make sure the banjo bolts are clean and get fresh crush washers at the same time. If you have an Earl's store nearby you can make the lines yourself and save some money (and get them fast.)

          Repeating myself but if you are getting strong fluid flow out of the lines at both calipers when the lever is pumped that means the calipers are the problem. More specifically, the pistons are not moving close enough to the disc and/or you have binding in the sliding pins. When in use the caliper piston moves extremely close to disc. When you grab the lever the pressure build up causes the piston to push the pads through incremental movement as the caliper piston seals flex. If the piston doesn't move close enough, or if the sliding pins are sticking, the piston can't move close enough for that hard pad contact to occur and the lever will feel soft. Aftermarket caliper parts can cause this binding to happen; I've fought this same problem several times in my past when K&L brake caliper seals were used. And make sure the sliding pins are lubed with some heavy black moly caliper grease. Not just some general purpose grease. You need the high temp stuff because the calipers can get really hot at times.
          Last edited by Nessism; 06-27-2020, 08:34 AM.
          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


            #35
            Originally posted by Nessism View Post
            I'd put a hard stop on the proceedings and change the brake lines. I'm doubtful that's the problem but they should be changed regardless. Make sure the banjo bolts are clean and get fresh crush washers at the same time. If you have an Earl's store nearby you can make the lines yourself and save some money (and get them fast.)

            Repeating myself but if you are getting strong fluid flow out of the lines at both calipers when the lever is pumped that means the calipers are the problem. More specifically, the pistons are not moving close enough to the disc and/or you have binding in the sliding pins. When in use the caliper piston moves extremely close to disc. When you grab the lever the pressure build up causes the piston to push the pads through incremental movement as the caliper piston seals flex. If the piston doesn't move close enough, or if the sliding pins are sticking, the piston can't move close enough for that hard pad contact to occur and the lever will feel soft. Aftermarket caliper parts can cause this binding to happen; I've fought this same problem several times in my past when K&L brake caliper seals were used. And make sure the sliding pins are lubed with some heavy black moly caliper grease. Not just some general purpose grease. You need the high temp stuff because the calipers can get really hot at times.
            I thought I'd head to the store this morning and get some large latex gloves and put each one of the calipers in a glove and seal them tight to the hoses and pump to see what happens. Thank you for the functionality of the brake system. I've been trying to figure that out as I go here and you've handed it to me in this post. Thanks Ed!

            I'll google earls brake lines and see what pops up locally.
            1978 Suzuki GS 750 EC

            Comment


              #36
              No Earl's store here in Florida.

              I took the MC cup and plate off and cleaned a little more. Both holes squirt fluid when I gripped the handle. The left hole shot fluid and hit my forehead LOL. I don't know what happened to the right side I was too busy bobbing and weaving to notice. The right side was evident with the second more gentile pull. I wrapped both calipers with cling wrap after greasing the pads on both calipers. Cling wrap is shvt. It is now in my trash can and now longer welcome in this house.

              The under side of the right caliper was wet with fluid. Just a wee bit. Before I wrapped and checked out the well. I'm going to bring the bike in the house and submerge both calipers in the tub and check for air bubbles. Don't laugh. I've seen air bubbles in the tub before.
              Last edited by Shred Astaire; 06-27-2020, 02:52 PM.
              1978 Suzuki GS 750 EC

              Comment


                #37
                The right front caliper is weeping from the top seal.
                1978 Suzuki GS 750 EC

                Comment


                  #38
                  Originally posted by Shred Astaire View Post
                  The right front caliper is weeping from the top seal.
                  All right! Progress.

                  Now which one of them four hippies in the avatar is you?
                  1982 GS1100E V&H "SS" exhaust, APE pods, 1150 oil cooler, 140 speedo, 99.3 rear wheel HP, black engine, '83 red

                  2016 XL883L sigpic Two-tone blue and white. Almost 42 hp! Status: destroyed, now owned by the insurance company. The hole in my memory starts an hour before the accident and ends 24 hours after.

                  Comment


                    #39
                    Originally posted by Rob S. View Post
                    All right! Progress.

                    Now which one of them four hippies in the avatar is you?
                    None, I've only wanted to be in a group since I was drummer in a garage band when I was 13. It's from the movie "Almost Famous" If you want to go back to 1973 for a couple of hours it's a great movie.

                    1978 Suzuki GS 750 EC

                    Comment


                      #40
                      You're kidding! I thought it was Led Zep. The eyes are the first to go. And the legs. And...
                      1982 GS1100E V&H "SS" exhaust, APE pods, 1150 oil cooler, 140 speedo, 99.3 rear wheel HP, black engine, '83 red

                      2016 XL883L sigpic Two-tone blue and white. Almost 42 hp! Status: destroyed, now owned by the insurance company. The hole in my memory starts an hour before the accident and ends 24 hours after.

                      Comment


                        #41
                        Originally posted by Nessism View Post
                        I'd put a hard stop on the proceedings and change the brake lines. I'm doubtful that's the problem but they should be changed regardless. Make sure the banjo bolts are clean and get fresh crush washers at the same time. If you have an Earl's store nearby you can make the lines yourself and save some money (and get them fast.)

                        Repeating myself but if you are getting strong fluid flow out of the lines at both calipers when the lever is pumped that means the calipers are the problem. More specifically, the pistons are not moving close enough to the disc and/or you have binding in the sliding pins. When in use the caliper piston moves extremely close to disc. When you grab the lever the pressure build up causes the piston to push the pads through incremental movement as the caliper piston seals flex. If the piston doesn't move close enough, or if the sliding pins are sticking, the piston can't move close enough for that hard pad contact to occur and the lever will feel soft. Aftermarket caliper parts can cause this binding to happen; I've fought this same problem several times in my past when K&L brake caliper seals were used. And make sure the sliding pins are lubed with some heavy black moly caliper grease. Not just some general purpose grease. You need the high temp stuff because the calipers can get really hot at times.
                        Replaced the brake lines yesterday and the brakes are now working. Thank you all.
                        1978 Suzuki GS 750 EC

                        Comment


                          #42
                          Originally posted by Nessism View Post
                          I'd put a hard stop on the proceedings and change the brake lines. I'm doubtful that's the problem but they should be changed regardless. Make sure the banjo bolts are clean and get fresh crush washers at the same time. If you have an Earl's store nearby you can make the lines yourself and save some money (and get them fast.)

                          Repeating myself but if you are getting strong fluid flow out of the lines at both calipers when the lever is pumped that means the calipers are the problem. More specifically, the pistons are not moving close enough to the disc and/or you have binding in the sliding pins. When in use the caliper piston moves extremely close to disc. When you grab the lever the pressure build up causes the piston to push the pads through incremental movement as the caliper piston seals flex. If the piston doesn't move close enough, or if the sliding pins are sticking, the piston can't move close enough for that hard pad contact to occur and the lever will feel soft. Aftermarket caliper parts can cause this binding to happen; I've fought this same problem several times in my past when K&L brake caliper seals were used. And make sure the sliding pins are lubed with some heavy black moly caliper grease. Not just some general purpose grease. You need the high temp stuff because the calipers can get really hot at times.
                          Is the sliding pins the round bars the brake pads hangs from? I did not realize those should be lubricated (mine were just dusty and rusty). I polished them shiny though.
                          GS1000G 1981

                          Comment


                            #43
                            Originally posted by Noreg View Post
                            Is the sliding pins the round bars the brake pads hangs from? I did not realize those should be lubricated (mine were just dusty and rusty). I polished them shiny though.
                            No, those are not the pins. I'm talking about the large bolts that the caliper slides on. Suzuki calls them axles. Items 9 & 10 in this diagram...https://www.partzilla.com/catalog/su...front-calipers
                            Last edited by Nessism; 08-12-2020, 10:27 AM.
                            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


                              #44
                              Originally posted by Nessism View Post
                              No, those are not the pins. I'm talking about the large bolts that the caliper slides on. Suzuki calls them axles. Items 9 & 10 in this diagram...https://www.partzilla.com/catalog/su...front-calipers
                              Ah, the rear caliper is different, that makes sense.
                              GS1000G 1981

                              Comment


                                #45
                                My suzuki specifies DOT4 on the master cylinder, a square one, not round.
                                sigpic Too old, too many bikes, too many cars, too many things

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