Fork Seal Maintenance

Leaking fork seals have fast become the scourge of the modern motorcycle. Whilst the common term “blown seal” is used to describe a leak quite often the seal is actually okay.

Most seals leak due to foreign matter (dirt , grass particles etc) being trapped between the sealing lip and the fork tube. This creates an escape path for the oil and a well known scenario follows….leaky seals.

The leaking seal is not only inconvenient but can also be quite dangerous. Often the oil can find its way onto brake systems and front tyres. Obviously oil on the tyre is a much bigger problem for road bikes than dirt bikes due to the riding surface interaction. In cases where seals are damaged it is usually due to corresponding damage to the chrome tubes. Nicks in the chrome from roost or impacts create high spots that will tear the seal lip causing failure.

When a bike is rarely ridden or aggressive cleaning solutions such as CT18 are used it is possible for the chrome tube to lose its oil film and become very dry. In this case the seal is forced to encounter a high friction situation which can cause premature wear or hardening of the seal lip thus promoting failure. When compressing forks during transport, people often notice oil that has been forced past the seals. This often rights itself when riding but is a indicator that perhaps dirt is starting to build up within the seal.

Follow these simple guidelines to increase seal life…

Place a strip of foam between the oil seal and dust seal appr. 10mm x 10mm and of sufficient length for your fork. Lubricate with WD40 or a bit of fork oil. This will act as a filter and trap any dirt that gets past the dust seal. Remove and clean the foam after every few rides.

If you haven’t ridden the bike for a while or you use products like CT18, spray a little WD40 on your finger and wipe around the chrome tube just below the seal. This will lubricate the seal and prevent undue wear.

When transporting the bike with tie downs, release the built up air pressure via the bleed screw. Remember to let the air back in before you ride.