Fork seal
As fork sealing rings is referred to the attached between the outer and inner fork tube oil-tight oil seals on the motorcycle fork .
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Basically, this is a faulty design, as the shaft sealing rings used are designed to seal rotating shafts and not to the hydraulic rams that move in the axial direction . The fork sealing rings are therefore subject to constant wear due to operating movements, corrosion of the inner fork tubes and, above all, contamination on the inner fork tube, which is driven under the sealing ring sleeve by the spring movement.
In the past, bellows were widespread in order to minimize wear and tear , but are now practically only found on enduros and other off-road motorcycles. Street motorcycles, on the other hand, sometimes have short protective shields to minimize the stress on the chrome layer on the fork tubes from impacting foreign bodies.
Another design disadvantage is the breakaway force of the front suspension caused by the pretensioned sealing rings .
Fine traces of oil that remain on the standpipe when rebounding indicate the need to replace it as soon as possible, as otherwise there is a risk that leaking lubricating oil will drip onto the brake disc, which reduces its effectiveness to zero.