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1977 GS750 Front Brake Rebuild - HELP!

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    1977 GS750 Front Brake Rebuild - HELP!

    Hi folks, I'm just finishing the restoration of my 1977 GS750.
    The bike was a US import (I'm UK based) and when I bought a caliper rebuild kit I was surprised to find that the piston seal was far too large for my calipers, and there's a dust boot that I can't see a groove for it to sit in.
    I know the rear dust boot sits over the caliper body, and I believe the front is meant to slot into a groove in the caliper, but I only have a groove for the piston seal.

    1. Can anyone advise if there are two sizes of piston? Which might explain why my piston seals appear to be too large
    2. Am I missing something with the dust boots? None were fitted to the calipers when I stripped them down but the bike has been a project for many years with many bodges so this isn't a surprise. I just can't see how they can fit into the caliper body without a groove for them to fit into.
    3. I'm missing one of the little metal stopper plates that fits into the caliper mounting bracket to prevent the pads from spinning. Are these available anywhere? They're not listed on CMSNL as a separate part.

    I'll go up to the workshop and measure my piston and the new seal tonight and will update with those dims. I'll grab some pics of the calipers too to help with the
    Many thanks,
    Tom.
    1977 Suzuki GS750

    #2
    If the seals are the wrong size its probable that the boot is the wrong part too. Could the caliper have been swapped out for a later unit? Some pics might help.
    sigpicDarryl from Kiwiland

    1982 GSX1100S Katana
    1982 GSX750S Katana
    1982 GS650G Katana

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      #3
      You need to go to a site like Partsila.com and look up the parts for the brake system. From the line drawing, you should be able to discern what's going on. You should look for a Factory Service manual. There are many in .pdf form online, manuals.lib has some. That will give you the definitive answer. Especially with a bike that people have bodged. Sent you a PM

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        #4
        The standard/wire wheel/ single disc front brake model has a larger diameter piston and seal.

        It sounds as though you have an E model with dual front discs/ cast wheel? Although, that came out in 78
        1978 GS 1000 (since new)
        1979 GS 1000 (The Fridge, superbike replica project)
        1978 GS 1000 (parts)
        1981 GS 850 (anyone want a project?)
        1981 GPZ 550 (backroad screamer)
        1970 450 Mk IIID (THUMP!)
        2007 DRz 400S
        1999 ATK 490ES
        1994 DR 350SES

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          #5
          So, I've done some digging.
          I have one twin disc caliper with a 38mm piston and one 43mm single disc caliper. Told you people had been bodging!

          I need to buy another twin disc caliper basically. It wouldn't surprise me if the bike is a 78 model - nothing else on the bike was done properly so why would import docs be any different lol.
          1977 Suzuki GS750

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            #6
            What's the engine & frame numbers?
            -Mal

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

            78 GS750E

            Comment


              #7
              Originally posted by allojohn View Post
              What's the engine & frame numbers?
              I'll have to get back to you on that, I know the engine and frame numbers don't match which apparently is how it came from the factory (is this true? read it on a few forums now that they rarely matched).
              The bike isn't at home, it lives at my in-laws so I'll have a look over the weekend.
              1977 Suzuki GS750

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                #8
                The '77-'79 models certainly did not match.
                -Mal

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

                78 GS750E

                Comment


                  #9
                  Here's the single setup on my 77. What does your master cylinder look like? DSC03854.jpg
                  1986 1150EF
                  2008 GS1250SEA

                  Comment


                    #10
                    That '77 is one fine motorcycle!

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