Forks & Parts
About Forks & Parts
Telescopic forks carry the front wheel and take every hit, and the seals at the top of each leg are the part that gives up first. When a seal fails, oil creeps down the fork tube and the fork loses damping. Owners shop here for fork seals, seal kits, dust seals and a few related items such as an oil level adjustment kit, a Showa fork bladder for a Honda and an MX fork clamp tie-down tube.
The key to a fork seal is its size. Seals are listed with three measurements, inner diameter by outer diameter by thickness, for example 35 mm by 48 mm by 11 mm or 41 mm by 53 mm. They must match your fork tube and the bore in the fork leg, and your service manual or the old seal gives the sizes. Replace the seals in both legs together, and check the fork tube for pitting or scratches, which will cut a new seal. After that, fill with the oil type and level your manual calls for.
Brands in this category include SDI, Parts Unlimited, PSR, SKF and Progressive Suspension. Pick your machine in the Ride Finder at the top of the page. For other front-end parts, see Steering Bearings, Shocks & Coil Overs and the parent category, Steering & Suspension.
FAQs on fork seals and fork parts
How do I read a fork seal size?
Fork seals are listed as inner diameter by outer diameter by thickness, such as 35 mm by 48 mm by 11 mm. The inner diameter matches the fork tube, and the outer diameter matches the bore in the fork leg. Your service manual lists the size for your fork, or you can measure the old seal.
How do I know a fork seal has failed?
The usual sign is oil on the fork tube or running down the leg, sometimes with oil on the brake or wheel. The fork may also feel less damped or lose travel control. A film of dust on the tube is normal, but fresh oil points to a leaking seal.
Should I replace the seals on both fork legs?
Yes, replace both together. They have the same age and wear, and matching them keeps the forks working the same on each side. Change the fork oil at the same time, using the type and level your service manual lists for your model.
Do dust seals matter?
Yes. A dust seal wipes dirt off the fork tube as it slides, which protects the oil seal underneath. A worn or torn dust seal lets grit reach the oil seal and shortens its life. Many seal kits include both, so check the listing.
Why does fork oil level matter?
Oil level sets the air space in the fork leg, which affects how the fork behaves near the end of its travel. Use the level your service manual gives, measured the way it describes. An oil level adjustment kit is listed here to help set it.
