’58 Big Twin Lower Crank Seal

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  • February 12, 2017 at 3:57 am #52864
    William Jatzek
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      Can a quad seal be used on a earlier model? Is it any much better than the O ring?

      February 12, 2017 at 4:31 am #52865
      chris-p
      Participant

        Yes the quad ring seals better.

        February 12, 2017 at 4:32 am #52866
        Mumbles
        Participant

          It shouldn’t be a problem as they all use the same carbon seal. The quad seal had to be an upgrade as it is similar to a double lipped oil seal and has two sealing surfaces in contact with the crankshaft instead of one, like on an O ring.

          February 12, 2017 at 4:38 am #52867
          vintin
          Participant

            When I replace the carbon seal on my 1957 RDE19 I upgraded to the quad ring. This was a year or so ago. Dan Gano, where I bought my parts, suggested it.

            February 12, 2017 at 11:42 am #52868
            frankr
            Participant

              The carbon seal must maintain contact with the bearing by sliding on the crankshaft as the shaft moves up and down within its limits. An o-ring tends to roll on the shaft instead of slide. A quad ring is designed for sliding operation. Thus the change.

              February 12, 2017 at 1:55 pm #52871
              Buccaneer
              Participant

                US Member

                Is the whole affair (carbon seal) only to keep water out of the
                crank bearing, or does it also help seal the crank case?
                Just pondering, as I was putting together the seal on
                my Fleetwin yesterday.

                Prepare to be boarded!

                February 12, 2017 at 2:27 pm #52872
                frankr
                Participant

                  Both

                  Edit: Well actually in the case of a fleetwin the bronze bearing is enough for sealing the crankcase compression, so the carbon seal is more for keeping the water out of the crankcase (and drive shaft splines). In the case of the Big Twin with a roller bearing, it does both–keep the water out and crankcase compression in.

                  February 12, 2017 at 5:26 pm #52875
                  William Jatzek
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                    Question 1. So if you can use the quad seal as an upgrade to replace ”O” ring inside carbon seal for earlier big twins.Would you also on earlier big twins use the later carbon ring # 302538 with the smaller surface area? Question 2. Would a quad seal fit in the earlier flat carbon seal? Question 3. what is the earliest year big Twin that would accept this modification?

                    February 12, 2017 at 6:37 pm #52879
                    chris-p
                    Participant
                      quote Billy J:

                      Question 1. So if you can use the quad seal as an upgrade to replace ”O” ring inside carbon seal for earlier big twins.Would you also on earlier big twins use the later carbon ring # 302538 with the smaller surface area? Question 2. Would a quad seal fit in the earlier flat carbon seal? Question 3. what is the earliest year big Twin that would accept this modification?

                      1. Yes if you have one available
                      2. Yes they do.
                      3. Very first RD10 (1951) used the carbon seals top and bottom of crank.

                      February 13, 2017 at 1:20 am #52902
                      William Jatzek
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                        Thanks Chris. I will keep this in mind when I do my next big twin.Another question came to mind. Are quad seals a current new made part available from Bombardier ( Evinrude) ? Or are the ones available now NOS stock maybe 30 + or more years old? Bill,

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