Running motor, flexshaft and prop unloaded ??

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  • JonD
    Senior Member
    • Jun 2011
    • 129

    #1

    Running motor, flexshaft and prop unloaded ??

    I have just received a Genesis and initially plan to run it with stock everything for a couple of runs. This is my first offshore electric, and I have spent a lot of time searching and "absorbing" related info on this forum. What a wealth of information there is!

    I've strengthened the motor mounts and reinforced where the stuffer tube comes through the hull (the motor and mounts had come loose in transit and the stuffer tube was loose through the hull). I have dismantled and greased the flexshaft etc with Grim Racer grease. Also increased all water pipes and outlet to 5/32 ID.

    I am running 2 x 2S in series with a Turnigy 180A ESC.

    My question is that when I run it up very briefly (just a second ot two) on the bench it gets to about 60% speed and then the shaft starts making a horrible vibrating noise and the Teflon liner starts rotating in the stuffer tube. Is this because the flexshaft is unloaded and thrashing about inside (just a guess), or does it indicate another problem? I was about to try it in the water, but thought I would check this on the forum first.

    Cheers,

    Jon
  • Boaterguy
    Fast Electric Addict!
    • Apr 2011
    • 1760

    #2
    I believe it is either the fact that it is unloaded or the fact that the brass tube is much lighter than it would be in the water, so it can vibrate easier.

    Comment

    • stadiumyamaha
      Fast Electric Addict!
      • Apr 2011
      • 1284

      #3
      also check to make sure your stuffing tube has a proper bend in it. A tube that does not have a bend will cause vibrations. My genesis strut was very low stock and needed bending and lifted a bunch. Be carefull though, the glue they use if very thin and its easy to break the tube loose while adjusting.
      white geico w/2200kv 3674 leopard 53.5mph 4s2p, geico w/ 1800kv outrunner 52mph on 4s2p, genesis w/2200kv castle 53.8 on 4s2p, impulse 31 w/2200kv castle, stock p1 and ul-1

      Comment

      • siberianhusky
        Fast Electric Addict!
        • Dec 2009
        • 2187

        #4
        When the flex is loaded it tries to coil itself up inside the stuffing tube, when on the water the flex really only touches in a few places down the stuffing tube, but this is enough to quiet it down, some of my boats sound like a bag of hammers on the bench but are very quiet on the water.
        If my boats upside down then who owns the one I thought I was driving the last two laps?

        Comment

        • JIM MARCUM
          Senior Member
          • Jun 2011
          • 773

          #5
          First, it's not a good idea to run your boat on the bench at anything over 10% throttle. Like siberianhusky said, when under load in the water the flex shaft coils up, becomes stiffer & a bit shorter than when not under a load. That's why you need to leave 1/32"-1/16" clearance between the drive dog & the strut. I also use a 1/16" thick "O" ring shaped slice cut off a large silicone tube as a cushion. It also helps seal the propshaft when under load. JIM
          JIM MARCUM: NAMBA 777; EX? SoCal FE Racers Club; D-19; Official 2012 NAMBA FE Nationals Rescue Diver; Purple Heart Viet Nam Vet; Professional SCUBA/HOOKA Diver, KELCO, 1973-1978; BBA 1978, Magna Cum Laude; MBA 1980 w/honors; Retired DOD GS1102-12 Contract Specialist

          Comment

          • JonD
            Senior Member
            • Jun 2011
            • 129

            #6
            Thanks for the info, guys.

            That all makes sense now.

            Cheers,

            Jon

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