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77 GS750B Front Caliber - What make/model will swap?

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    77 GS750B Front Caliber - What make/model will swap?

    Is anyone aware of an affordable rebuild kit for a 77 that contains ALL the dust boots and the seal? I've found a few kits online that claim to fit, but they're missing some of the dust boots. I can order the parts individually on Parts Outlaw, but just for the piston seal, 4 o rings and 4 dust boots (still missing the piston dust boot because it's unavailable) it would be $75. And I also need new pads and that piston boot which are dang near impossible to find. One ebay seller has pads and he wants $50. So I'd have nearly $150 into this caliber just in rubber parts and pads, and still be missing the piston boot seal. All the rubber on my caliber is cracked or shrunk so reusing is not an option.

    Is anyone aware of a caliber off a newer GS, or different model GS that will bolt up and work that is more affordable to rebuild and find parts for? FYI, this is a single front caliber if that matters.

    If anyone has a caliber they'd be willing to part with that would fit, I'd be happy to pay! (It'd be nice if it wasn't stuck too! )

    Appreciate the help!
    - 1983 GS850L ~ 30,000 miles and going up - Finally ready for a proper road trip!
    - 1977 GS750B - Sold but not forgotten

    #2
    Salty_Monk sells upgrade brackets - he's most likely to know what your options are.
    -Mal

    "The only reason for time is so that everything doesn't happen at once." - B. Banzai
    ___________

    78 GS750E

    Comment


      #3
      Does the 750B have an axle under the fork leg like your G or in front of it like the L? What size rotor is on it now? Is it a 274mm like the G or larger one (296mm)?
      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.....

      www.parasiticsanalytics.com

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

      Comment


        #4
        Originally posted by salty_monk View Post
        Does the 750B have an axle under the fork leg like your G or in front of it like the L? What size rotor is on it now? Is it a 274mm like the G or larger one (296mm)?
        Thanks for chiming in.

        Axle is under the fork leg like the G. Measuring the best I can with it on the bike, I measured 11.5" so that should be the 296mm. Center to center the mounting holes on the fork leg are ~71.5mm, slightly closer together than on my L. Not sure what the G measurement is. Picture below.

        20220104_174638

        Ideally I'm looking for the most "factory" replacement as possible, as in reusing current rotor, master cylinder and ideally being affordable to reseal if buying used and available pads that won't cost an arm and a leg.
        - 1983 GS850L ~ 30,000 miles and going up - Finally ready for a proper road trip!
        - 1977 GS750B - Sold but not forgotten

        Comment


          #5
          Your path of least resistance is to follow this setup using the blackbird rotor : https://www.thegsresources.com/_foru...00C&highlight=

          Looks like it's the same as the 550E or the 1000C if the rotor is that size. Have a double check as that looks like one of the smaller rotors (by the spider) as the larger ones are usually 1 piece. The difference in diameter is only 3/4" so not always easy to see when mounted. (approx 10 3/4" vs 11 5/8")

          The latest bracket accomodates the Ninja caliper or the more modern EX650 caliper (also the SV650 or DL650 caliper as they are the same). You can re-use the master & the lines (although I would be fitting new braided one if you haven't already).
          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.....

          www.parasiticsanalytics.com

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

          Comment


            #6
            Thanks for the information. Your blackbird rotor method is quite a bit more expensive than rebuilding my caliber considering I'd have to purchase the rare rotor and a caliber... Or are you suggesting it's possible to use my rotor with that same setup?

            I will pull the wheel off tomorrow and double check the rotor size.
            - 1983 GS850L ~ 30,000 miles and going up - Finally ready for a proper road trip!
            - 1977 GS750B - Sold but not forgotten

            Comment


              #7
              Dan's method is ideal if braking performance is important. If the end game is simply to improve your braking system, in many cases a later year GS/Tokico caliper will be a bolt on. Rebuild that, install a new braded stainless/teflon hose w/new pads, and the worlds your oyster.
              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


                #8
                Originally posted by Nessism View Post
                Dan's method is ideal if braking performance is important. If the end game is simply to improve your braking system, in many cases a later year GS/Tokico caliper will be a bolt on. Rebuild that, install a new braded stainless/teflon hose w/new pads, and the worlds your oyster.
                My end goal is a fun bike to ride around town. It will see zero track time and I don't ride hard at all. So factory performance is sufficient.

                @Burque73 is selling front calipers off a 1982 GS650G. Can't tell from the parts list image if they will fit or not. Does anyone know if they will?

                As for brake lines, I will be using Earls parts and building new ones.
                - 1983 GS850L ~ 30,000 miles and going up - Finally ready for a proper road trip!
                - 1977 GS750B - Sold but not forgotten

                Comment


                  #9
                  The G caliper should fit your bike, you may have to change to the 550E/1000C rotor worst case. I believe all the calipers will interchange except for L models.
                  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.....

                  www.parasiticsanalytics.com

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

                  Comment


                    #10
                    Originally posted by 93Bandit View Post
                    My end goal is a fun bike to ride around town. It will see zero track time and I don't ride hard at all. So factory performance is sufficient.
                    Believe me, the early hockey-puck calipers are utter rubbish compared to even the ones that came immediately after. That was my experience with two of them on the 79 850, and I was glad to discover the later calipers fitted straight on as a factory upgrade, if you like. Even the later ones aren't perfect, and they're out-performed by much more recent calipers and discs, as Dan suggests. However, as a cheap and effective upgrade, if you can get a low-mileage caliper from an 80-onwards bike, you'd notice the improvement.
                    ---- Dave
                    79 GS850N - Might be a trike soon.
                    80 GS850T Single HIF38 S.U. SH775, Tow bar, Pantera II. Gnarly workhorse & daily driver.
                    79 XS650SE - Pragmatic Ratter - goes better than a manky old twin should.
                    92 XJ900F - Fairly Stock, for now.

                    Only a dog knows why a motorcyclist sticks his head out of a car window

                    Comment


                      #11
                      Originally posted by Grimly View Post
                      Believe me, the early hockey-puck calipers are utter rubbish compared to even the ones that came immediately after. That was my experience with two of them on the 79 850, and I was glad to discover the later calipers fitted straight on as a factory upgrade, if you like. Even the later ones aren't perfect, and they're out-performed by much more recent calipers and discs, as Dan suggests. However, as a cheap and effective upgrade, if you can get a low-mileage caliper from an 80-onwards bike, you'd notice the improvement.
                      Thanks for the input. So the 82 GS650G should fit and be an upgrade in braking?
                      - 1983 GS850L ~ 30,000 miles and going up - Finally ready for a proper road trip!
                      - 1977 GS750B - Sold but not forgotten

                      Comment


                        #12
                        Originally posted by 93Bandit View Post
                        Thanks for the input. So the 82 GS650G should fit and be an upgrade in braking?
                        If the mount is the same and the diam / offset of the disc is the same, I think it will fit.
                        ---- Dave
                        79 GS850N - Might be a trike soon.
                        80 GS850T Single HIF38 S.U. SH775, Tow bar, Pantera II. Gnarly workhorse & daily driver.
                        79 XS650SE - Pragmatic Ratter - goes better than a manky old twin should.
                        92 XJ900F - Fairly Stock, for now.

                        Only a dog knows why a motorcyclist sticks his head out of a car window

                        Comment


                          #13
                          Originally posted by 93Bandit View Post
                          My end goal is a fun bike to ride around town. It will see zero track time and I don't ride hard at all. So factory performance is sufficient.

                          @Burque73 is selling front calipers off a 1982 GS650G. Can't tell from the parts list image if they will fit or not. Does anyone know if they will?

                          As for brake lines, I will be using Earls parts and building new ones.
                          I didn't list it, but I also have the front wheel with both rotors from that 650G. My thought was to hang onto an extra set of rotors to eventually swap them over onto the 850. Honestly, I'd much rather them help someone get back on the road than sit in a "maybe use eventually" pile here.

                          Let me know if I can help.
                          Roger

                          Current rides
                          1983 GS 850G
                          2003 FJR 1300A
                          Gone but not forgotten 1985 Rebel 250, 1991 XT225, 2004 KLR650, 1981 GS850G, 1982 GS1100GL, 2002 DL1000, 2005 KLR650, 2003 KLX400

                          Comment


                            #14
                            Originally posted by salty_monk View Post
                            The G caliper should fit your bike, you may have to change to the 550E/1000C rotor worst case. I believe all the calipers will interchange except for L models.
                            Pulled the wheel off and double checked rotor diameter. It's the 296mm.

                            Originally posted by Grimly View Post
                            If the mount is the same and the diam / offset of the disc is the same, I think it will fit.
                            Unsure about those measurements and I don't know if I can get them.

                            Originally posted by Burque73 View Post
                            I didn't list it, but I also have the front wheel with both rotors from that 650G. My thought was to hang onto an extra set of rotors to eventually swap them over onto the 850. Honestly, I'd much rather them help someone get back on the road than sit in a "maybe use eventually" pile here.

                            Let me know if I can help.
                            Thanks for chiming in Burque. I'm interested in at least one front caliber if it will fit my 750. Could you measure center to center of the mount holes on the fork leg to compare to mine? If that dimension is the same, maybe we can work something out. Also, are the caliper pistons free or are the stuck in need of rebuilding?

                            On a side note, I was really hoping to have this bike road ready come spring, but it seems like every where I turn there's something else that needs to be fixed. Joys of working on older machines! My wife and I are expecting our 2nd child end of April, so after that I won't have any garage time for a while so I really want to get this thing going before that, budget permitting. Fingers crossed!

                            As always, all the help from everyone is greatly appreciated!
                            - 1983 GS850L ~ 30,000 miles and going up - Finally ready for a proper road trip!
                            - 1977 GS750B - Sold but not forgotten

                            Comment


                              #15
                              Originally posted by 93Bandit View Post
                              Pulled the wheel off and double checked rotor diameter. It's the 296mm.



                              Unsure about those measurements and I don't know if I can get them.



                              Thanks for chiming in Burque. I'm interested in at least one front caliber if it will fit my 750. Could you measure center to center of the mount holes on the fork leg to compare to mine? If that dimension is the same, maybe we can work something out. Also, are the caliper pistons free or are the stuck in need of rebuilding?

                              On a side note, I was really hoping to have this bike road ready come spring, but it seems like every where I turn there's something else that needs to be fixed. Joys of working on older machines! My wife and I are expecting our 2nd child end of April, so after that I won't have any garage time for a while so I really want to get this thing going before that, budget permitting. Fingers crossed!

                              As always, all the help from everyone is greatly appreciated!

                              The mounting holes are 72.43mm or 2-27/32" center to center, give or take a hair.

                              Since the calipers are already off of the forks I struggled to get the bolts (axles?) out to separate it and check the piston. It got late and it's cold in the garage too. I may try a bit of compressed air to move the piston tomorrow. The climate here and in Colorado where this bike lived is pretty dry, plus all of the fluids I drained from this 650 were the appropriate colors so the PO took care of maintenance it seems.

                              What if you took both calipers, the fork legs, rotors and scrounged up a spoke wheel that you could put another rotor on. That'd be a sweet upgrade. Sounds too easy though. The upper fork tubes are 35mm. Would they even fit a 750? These are 31-3/16 long from the top to center of the axle.
                              Roger

                              Current rides
                              1983 GS 850G
                              2003 FJR 1300A
                              Gone but not forgotten 1985 Rebel 250, 1991 XT225, 2004 KLR650, 1981 GS850G, 1982 GS1100GL, 2002 DL1000, 2005 KLR650, 2003 KLX400

                              Comment

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