MXA TEAM TESTED: SKF DUAL-COMPOUND FORK SEALS

WHAT IS IT? SKF has a reputation for building the longest-lasting and best fork seals in the motocross biz, and its dual-compound innovation goes a long way toward enhancing that reputation.

WHAT’S IT COST? $43.99.

CONTACT? www.innteck-usa.com, (866) 252-8772 or your local dealer.

WHAT STANDS OUT? Here’s a list of things that stand out with SKF’s dual-compound fork seals and dust wipers.

(1) Leakers. The MXA wrecking crew goes through fork seals at the rate of one a week. That may sound bad, but we have over 25 test bikes that we race constantly. The harsh realities of racing in gritty soil guarantee that at any given time one of our test bikes will have oil oozing towards the front brake rotor. A leaking fork seal means downtime, because modern upside-down forks require a modicum of know-how and tools to replace a fork seal. So, when someone releases a new-style fork seal, we are on it right away.

(2) Dual-compound.  As a rule of thumb, we put SKF dual-compound fork seals in every leaker that we have. This allowed us to build a fleet of MXA test bikes with SKF’s newest seal. The technology attracted us because the new seals promised superior sealing, better wiping of dirt, less fork stiction and longer life. SKF dual-compound fork-seal technology was developed to achieve superior sealing performance by molding two different compounds together in one fork seal.

The green compound rubber is used for the fork seal’s wipers. It is tough and durable. The red compound rubber is used against the fork tubes. It is softer, more flexible and has a newly designed sealing lip. The softer rubber can follow imperfections in the fork tube to maintain a good seal against leakage. Helping the dual-compound rubber is a metal insert that provides structural integrity, and the fork wiper has a self-cleaning, open-wind spring to increase the seal pressure of the wiper. 

(3) Experience. Experience has revealed to us that Kayaba seals are most likely to leak. Showa seals are second-most likely, and WP seals are the least likely. Why? Because KTM’s WP forks come stock with SKF fork seals (although not dual-compound seals). A fork seal lives in a dirty environment where it has to endure a very long stroke at high shaft speeds with instantaneous direction changes. When you add the side loads, contamination and migration of particles to the picture, it is amazing that any seal can live up to the demands of motocross—and most don’t.

For our long-term test, we fixed every leaking OEM seal with a replacement SKF dual-compound fork seal. We can’t say that we never had an SKF dual-compound fork seal fail, but we can say that those failures were because of rock dings to the fork leg’s chrome that tore the seal’s lip. Across the board, the dual-compound seals offer less stiction, superior sealing and longer life.

WHAT’S THE SQUAWK? Price. SKF fork seals cost more than most aftermarket seals, although the price does include a new dust seal. Given the cost of replacing fork seals, the price of a seal that lasts twice as long is worth it.

MXA RATING: If you want to eliminate the odds of a fork-seal leak, you need to run the best seals possible. In MXA’s opinion, the best seals available are SKF dual-compound fork seals.

 

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