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Improved Shimano 8-speed sealing and part numbers

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  • j_0_h_n_b
    I acquired a 2nd-hand Nexus 8-speed hub (SG-8R25) in December, and inspected it to find it was still covered in clean white grease, and surmised that it hadn t
    Message 1 of 4 , Feb 3, 2011
      I acquired a 2nd-hand Nexus 8-speed hub (SG-8R25) in December, and inspected it to find it was still covered in clean white grease, and surmised that it hadn't been ridden much. Knowing of the reports of poor sealing, when I put it back together, I put a good smear of vacuum grease on the rim of the large plastic cap and the rubber seal. This stuff is like vaseline and is hard to wash off the hands.
      I've now ridden it for about 8 weeks, and have taken it apart to find that the hub innards were rusting, worst near the sprocket end. I'm a bit disgusted... this is not low maintenance cycling, nor sealed for life. I had none of the Shimano grease, so have temporarily filled it with automatic transmission fluid.

      Shimano say that new seals "greatly increase waterproofing" on more recent 8-speed hubs and that these should retrofit the 8-speed range. The problem I'm having is that the Shimano data sheet for the SG-8R25 lists the plastic cap as Y-34R 98110 (Right Hand Dust Cap A with seal) and the smaller rubber lipped seal as Y-34R 0E000 (Right Hand Dust Cap B)
      If I order these, will I get uprated versions of the ones I already have, or will they be the identical to the originals? Why I am puzzled is that if I go to a data sheet of a more recent model hub, like the SG-8R36, that claims to be uprated, it too list the same part numbers stating they are the "B specification", and also list part numbers Y-37G 98080 and Y-36R 07000 as "A specification" --- the difference being how large a sprocket can be accommodated. If anyone can help me out with what I should order, I'd be grateful.

      Sorry that this has been a bit wordy,
      john

      SG-8R25 data sheet and SG-8R36 data sheet 
    • Rich W
      Darned if I know how Shimano works that. Based on the lack of answers it looks like such lack of knowledge is the norm. I would order the part numbers from
      Message 2 of 4 , Feb 4, 2011
        Darned if I know how Shimano works that. Based on the lack of answers it looks like such lack of knowledge is the norm. I would order the part numbers from the latest 8 speed hub you can download documentation on or at least compare part numbers from the 8R25 parts list and the latest hub version parts list to determine if there are differences. I would still order the latest part numbers you can find.

        Rich Wood

        --- In Geared_hub_bikes@yahoogroups.com, "j_0_h_n_b" <j_0_h_n_b@...> wrote:
        >
        > I acquired a 2nd-hand Nexus 8-speed hub (SG-8R25) in December, and
        > inspected it to find it was still covered in clean white grease, and
        > surmised that it hadn't been ridden much. Knowing of the reports of poor
        > sealing, when I put it back together, I put a good smear of vacuum
        > grease on the rim of the large plastic cap and the rubber seal. This
        > stuff is like vaseline and is hard to wash off the hands.
        > I've now ridden it for about 8 weeks, and have taken it apart to find
        > that the hub innards were rusting, worst near the sprocket end. I'm a
        > bit disgusted... this is not low maintenance cycling, nor sealed for
        > life. I had none of the Shimano grease, so have temporarily filled it
        > with automatic transmission fluid.
        >
        > Shimano say that new seals "greatly increase waterproofing" on more
        > recent 8-speed hubs and that these should retrofit the 8-speed range.
        > The problem I'm having is that the Shimano data sheet for the SG-8R25
        > lists the plastic cap as Y-34R 98110 (Right Hand Dust Cap A with seal)
        > and the smaller rubber lipped seal as Y-34R 0E000 (Right Hand Dust Cap
        > B)
        > If I order these, will I get uprated versions of the ones I already
        > have, or will they be the identical to the originals? Why I am puzzled
        > is that if I go to a data sheet of a more recent model hub, like the
        > SG-8R36, that claims to be uprated, it too list the same part numbers
        > stating they are the "B specification", and also list part numbers Y-37G
        > 98080 and Y-36R 07000 as "A specification" --- the difference being how
        > large a sprocket can be accommodated. If anyone can help me out with
        > what I should order, I'd be grateful.
        >
        > Sorry that this has been a bit wordy,
        > john
        >
        > SG-8R25 data sheet
        > <http://techdocs.shimano.com/media/techdocs/content/cycle/EV/bikecompone\
        > nts/SG/EV-SG-8R25-2315F_v1_m56577569830688599.pdf> and SG-8R36 data
        > sheet
        > <http://bike.shimano.com/media/techdocs/content/cycle/EV/bikecomponents/\
        > SG/EV-SG-8R36-2784B_v1_m56577569830714873.pdf>
        >
      • Tom
        ... Did I miss the memo? Where does a citizen cyclist get individual component parts for Shimano IGHs in N.A.? Thanks!
        Message 3 of 4 , Feb 4, 2011
          > I would order the part numbers from
          > the latest 8 speed hub...

          > > If I order these...

          Did I miss the memo? Where does a citizen cyclist get individual component parts for Shimano IGHs in N.A.?

          Thanks!
        • j_0_h_n_b
          Just to update this thread for info. I ve sorted this now. I took a gamble and it seem that the uprated seals are the A-spec ones in the data sheets for
          Message 4 of 4 , Oct 4, 2011
            Just to update this thread for info.
            I've sorted this now. I took a gamble and it seem that the uprated seals are the "A-spec" ones in the data sheets for later models in the Nexus range.

            So you need part numbers Y-37G 98080 and Y-36R 07000 to update your old 8-spd Nexus hub.

            I obtained these from Petra Cycles in the UK (petracycles.co.uk) for about £6 using these component numbers:
            37G9808 ------> "SG-8C31 Right Hand Dust Cap A with Seal"
            36R0700 ------->"SG-8R22 Nexus Right Hand Dust Cap C"

            You'll need both. The most obvious difference is the metal dust cover over the rubber seal is now silvery and a lot larger

            HTH

            --- In Geared_hub_bikes@yahoogroups.com, "Tom" <prester_john_in_cathay@...> wrote:
            >
            > > I would order the part numbers from
            > > the latest 8 speed hub...
            >
            > > > If I order these...
            >
            > Did I miss the memo? Where does a citizen cyclist get individual component parts for Shimano IGHs in N.A.?
            >
            > Thanks!
            >
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