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you wouldn't think a fuel tank could be noisy.

Discussion in 'Fuel System & Electrics' started by rstucke, Sep 5, 2020.

  1. rstucke

    rstucke Well-Known Member

    Wamberal NSW AUS
    When I put the new Python exhaust into Blitz., a droning noise krept in that wasn't there with the old exhaust.
    After some mucking about I worked out the rear bumper rings like a bell when struck.
    The new exhaust extractors run parallel to the bumper so easy fix. I applied sound deadener to the inside of the bumper. Filled the tank went for a drive, problem solved.
    On a trip recently a small amount of the noise was still there. Because I was sensitive to the original droning
    it anoyed me, but Kym couldn't here it.
    And then the penny dropped. When I filled the tank the noise went away completely. At about half tank the noise came in arount 80kmh went out about 90kmh, louder as the tank got lower.
    The tank came out of Blitz so long ago in the restoration, I can't remember if there was any isolation involved.
    Rest asured there will be soon.
    I don't know if anyone has had the same sort of problem, specially if you've used sound deadening material to keep noise down. The sound the harmonic in the tank is like drone, drone, drone, drone at about 80kmh.
    almost like a trans noise but softer.
  2. Alpal

    Alpal Moderator Staff Member

    Melbourne Bend of Islands
    Schmett had a metalic rattle that we have not resolved. Exhaaust? Engine/gearbox mounts? Tank vent pipes? Screwdriver dropped in a cavity somewhere?
    Will find it one day.
  3. David H

    David H Well-Known Member

    All road vibes go up thru the body. Harmonic (or not) resonate frequency;).
    What's above the rotation.
    The tank.
    Just a suggestion.
    You got that access point to do fuel gauge?
    Put a pressure point on the tank top to keep pressure on tank upper edge as contents change to keep metal stress consistent. That will talk 'tune' & where vibe comes from.
    I'd wedge a stick into the gap to keep permanent metal pressure on the top of the tank.
    Applying a permanent pressure to the empty part of the tank to be the 'pillow'! Like drummers do!

    Last edited: Sep 6, 2020

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