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    Sludge in old final drive oil

    Now that my 80 GS1000G is finally on the road, I've changed my secondary and final drive oil, following Basscliff's excellent instructions. I have no idea how long it's been since this was last done. The bike has just under 16k on the odometer.

    The old secondary drive gear oil was black but looked otherwise clean (no noticeable debris). The final drive oil was also black, but there was some sludge built up on the drain plug. Assuming the plug is magnetic, then maybe that sludge was metallic. But maybe it's just oxidized oil buildup.

    How concerned should I be about the condition of the final drive?
    80 GS1000GT
    Past bikes:
    82 GS750E
    92 VFR750
    85 CB650

    #2
    I wouldn't worry about it - some very fine metallic "sludge" sticking to the drain plug is perfectly normal. Hypoid gears slide across each other a bit as they engage.

    Plus, yours might never been changed.

    Now, chunks of metal are a problem...
    1983 GS850G, Cosmos Blue.
    2005 KLR685, Aztec Pink - Turd II.3, the ReReReTurdening
    2015 Yamaha FJ-09, Magma Red Power Corrupts...
    Eat more venison.

    Please provide details. The GSR Hive Mind is nearly omniscient, but not yet clairvoyant.

    Celeriter equita, converteque saepe.

    SUPPORT THIS SITE! DONATE TODAY!

    Co-host of "The Riding Obsession" sport-touring motorcycling podcast at tro.bike!

    Comment


      #3
      Thanks, Brian - that's reassuring. I did look carefully for chunks / shavings, and found none.
      80 GS1000GT
      Past bikes:
      82 GS750E
      92 VFR750
      85 CB650

      Comment


        #4
        I'm with Brian on this one.
        It's likely it hasn't been changed at all, ever.
        My forks, secondary and final had very picturesque sludge.
        Do another change soon-ish and it will confirm whether you have an ongoing problem or just neglect that needed flushing.
        97 R1100R
        Previous
        80 GS850G, 79 Z400B, 85 R100RT, 80 Z650D, 76 CB200

        Comment


          #5
          Regarding the final drive it may be the po has over greased the splines with moli grease and it has pushed through the oil seal into the oil and discoloured it (ask me how I know) I have not seen secondary oil black though, not sure how that has happened as said before change both oils and run it a while and drain again if there is a problem it will show.
          The big guy up there rides a Suzuki (this I know)
          1981 gs850gx

          1999 RF900
          past bikes. RF900
          TL1000s
          Hayabusa
          gsx 750f x2
          197cc Francis Barnett
          various British nails

          Comment


            #6
            Thanks guys - I definitely will re-replace the fluid pretty soon. It certainly can't hurt, and will probably flush more sludge out.

            As for grease... I didn't see any specification for grease in either the secondary or final drive maintenance, but then, I'm still learning...
            80 GS1000GT
            Past bikes:
            82 GS750E
            92 VFR750
            85 CB650

            Comment


              #7
              Originally posted by ChrisMA View Post
              Thanks guys - I definitely will re-replace the fluid pretty soon. It certainly can't hurt, and will probably flush more sludge out.

              As for grease... I didn't see any specification for grease in either the secondary or final drive maintenance, but then, I'm still learning...
              There are tons of threads about how the shaft drive spline in the wheel strips out and how it's critical to grease the spline anytime the wheel is removed. Try searching on "moly grease" or "moly 60" and you will find tons of info.
              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 ChrisMA View Post
                As for grease... I didn't see any specification for grease in either the secondary or final drive maintenance, but then, I'm still learning ...
                the moly grease I mentioned as a possible point of oil contamination
                comes from someone over greasing the splines on the final drive to rear wheel
                when the wheel is put back in it can force excess grease under the oil seal and into the oil discolouring it
                The big guy up there rides a Suzuki (this I know)
                1981 gs850gx

                1999 RF900
                past bikes. RF900
                TL1000s
                Hayabusa
                gsx 750f x2
                197cc Francis Barnett
                various British nails

                Comment


                  #9
                  Originally posted by Nessism View Post
                  There are tons of threads about how the shaft drive spline in the wheel strips out and how it's critical to grease the spline anytime the wheel is removed. Try searching on "moly grease" or "moly 60" and you will find tons of info.
                  Thanks, Ed - I haven't had the rear wheel off yet, but that's another thing to look at. I've started looking at the moly 60 threads.

                  So much to learn
                  80 GS1000GT
                  Past bikes:
                  82 GS750E
                  92 VFR750
                  85 CB650

                  Comment


                    #10
                    The molybdenum paste is actually abrasive to plastic and rubber seals, so the trick for greasing the splines is to get enough to protect the parts without goobering on so much that it gets crammed into the seal.

                    And yes, the paste on this coupling is mandatory, and I'd say fewer than 1 out of 10 motorcycle shops have any idea you should use a specific lubricant and not just ordinary grease. And I call it "paste" because it is NOT a grease; it's made specifically to prevent metal to metal fretting wear in splined couplings; it's not suitable for parts that move.

                    For reasons unfathomable, Honda shops no longer sell the 60% moly paste that was perfect for this. I'm not sure what they use on Gold Wings and such nowadays. The moly grease found in parts stores has a very low percentage of molybdenum, 6% or 7%; better than leaving the coupling dry, but mostly useless for this application.

                    I believe this stuff is the closest actually currently available equivalent (hopefully this link works):


                    8 oz should last you about 50 years...
                    1983 GS850G, Cosmos Blue.
                    2005 KLR685, Aztec Pink - Turd II.3, the ReReReTurdening
                    2015 Yamaha FJ-09, Magma Red Power Corrupts...
                    Eat more venison.

                    Please provide details. The GSR Hive Mind is nearly omniscient, but not yet clairvoyant.

                    Celeriter equita, converteque saepe.

                    SUPPORT THIS SITE! DONATE TODAY!

                    Co-host of "The Riding Obsession" sport-touring motorcycling podcast at tro.bike!

                    Comment


                      #11
                      Originally posted by bwringer View Post
                      The molybdenum paste is actually abrasive to plastic and rubber seals, so the trick for greasing the splines is to get enough to protect the parts without goobering on so much that it gets crammed into the seal. .... 8 oz should last you about 50 years...
                      Thank you, Brian - added to my shopping list. I'll take the wheel off at the end of the season and do a careful re-greasing. My bike is nearly 40 now, so the paste should last just up until it's centennial birthday. I'll be sure to add it to my will.
                      80 GS1000GT
                      Past bikes:
                      82 GS750E
                      92 VFR750
                      85 CB650

                      Comment


                        #12
                        Originally posted by bwringer View Post
                        ..... I'm not sure what they use on Gold Wings and such nowadays.

                        8 oz should last you about 50 years...
                        The 1800's are single sided swing arms and have no need for this lubrication -
                        As for ME - I bought 2 tubes of the old Honda 60 when I heard they were going out of availability -
                        So MY personal stock is deep in goo right now -
                        Seeing as I only use it on my GS now-a-days I think 2 tubes will last my lifetime
                        As for the Goldwing owners who did not stock up...

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