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Fork damper upgrade

Discussion in 'Norton Commando Motorcycles (Classic)' started by jseng1, Jul 13, 2019 at 10:28 AM.

  1. jseng1

    jseng1

    Joined:
    Nov 26, 2009
    I made some fork damper improvement tests.

    With used stock components and 20 wt oil you can pull the damper rod up by hand in about 3 seconds.

    With a new top cap and the cup flaired to .680″ you can pull up the damper rod in about 5 seconds.

    With a new top cap and the cup flaired to .685″ you can pull up the damper rod in about 9 seconds.

    Those are significant improvements.

    The top cap should be sleeved with brass tubing as shown at:
    https://jsmotorsport.com/js-motorsport-technicalmore-norton-fork-upgrades/

    The brass tubing tightens the clearance at the damper rod and provides longer life.
     
    fiatfan and nortriubuell like this.
  2. CanukNortonNut

    CanukNortonNut

    Joined:
    Aug 8, 2005
    Very good Jim.
    Thanks for the enlightenment. Would you use the progressive spring instead of the stock.
    Cheers,
    Tom
     
  3. jseng1

    jseng1

    Joined:
    Nov 26, 2009
    I haven't used progressive springs so can't advise. But the damping mods work great.
     

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