JS Motorsport Technical
Fork Damping Sleeves

fork spacer

The aluminum sleeves are slit and expanded so they can be pushed into place by hand and have just the right tension so they stay located at the top of the slider without moving. The top sleeve covers up the large oil bleed hole in the fork tube when it nears full extension, thus creating a hydraulic bump stop to eliminate the harsh metallic “clunking” sound of Norton forks. Will not restrict fork travel. Special short 1/8″ plugs (not shown) are provided for blanking off the oil escape hole at the bottom of the fork tubes just above the lower bushing in order to make this kit really work.

damp tubes

The bottom sleeves fit over the bottom of the damper tubes to cover the oil bleed holes below the conical section.  If you already have large 1/4″ holes in (or above) the conical section then you are finished.  But if there is no hole then you must drill a new one.  A single 1/16″ hole in the conical section or just above the conical section will prevent cavitation and you will now have a hydraulic bump stop to prevent metal to metal bottoming. The single 1/16″ hole will also give you some compression damping.  Drilling larger will eliminate compression dampening.

For slippery Turcite fork bushings and damping upgrades (see Fork upgrades).