Koni – What Is Frequency Selective Damping?

Just like with most other vehicle modifications, when tuning your suspension there is always going to be a trade-off between performance and comfort. Spirited driving generally requires more aggressive damping, while street cruising and highway commutes are much more comfortable with less damping force. Which leaves many weekend warriors weary of upgrading their suspension for fear of ruining the comfort they crave on their daily commute.

Koni has been in the automotive damper industry since the early 1930s and has always found a way to be at the forefront of innovation. Having produced the first adjustable automotive shock absorber and electronic drag racing shock, it’s only natural that we should be taking a close look at one of Koni’s latest patents, Frequency Selective Damping (FSD).

FSD technology has its roots in Formula 1, with Koni having spent several years working directly with McLaren, at Monza, developing this damping design. “We found that the answer to a good line through the chicanes was to actually hit the berms,” explains Lee Grimes of Koni. If the damper could forgive the high frequency impact of the berm, the tire would settle down much faster and get planted. Whereas if the tire is still bouncing, you don’t have a solid footprint and have to wait that extra fraction of a second before it stabilizes. That’s the kind of thing FSD helps to filter out.”

Left: Low frequency valve actuation. Right: High frequency valve actuation.

Innovation is what separates the winners from the losers in this industry. No other shock design currently available on the market is capable of offering the added tuning feature of dual frequency mechanical damping that Koni found was needed to provide optimal handling and comfort, which meant that their engineers had to design it from scratch.

Frequency Selective Damping not only looks at piston speed, but also the frequency (or duration) of a particular input on the damper. Low frequency movements are connected to body control, and high frequency is directly related to axle input. In most shocks available today, damping performance is controlled by the oil flow moving through the piston assembly. FSD retains this pass through function with the added ability to also control oil flow parallel to the fluid going through the piston, which delays the buildup of pressure.

The valving of an FSD shock is able to filter out both of these actuation frequencies by using a creative internal design. When a FSD equipped damper experiences a low frequency input, which is common during cornering and heavy braking situations, the bypass valve is closed for more aggressive damping to provide additional stability and confidence.

When driving normally or exposed to high frequency inputs, which is common on rough roads or at higher speeds, the valve will open to soften the damping, giving the driver more comfort, confidence and control.

Frequency Selective Damping is the perfect option for someone wanting the same feel given by magnetic ride control type suspension, but with more control and at a fraction of the cost. It really is the best of both worlds, a smooth feel over rough surfaces at high speed and confidence-inspiring control under heavy braking and on winding roads and race tracks.

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About the author

Kyle Kitchen

Born and raised in Southern California, Kyle has been a gearhead ever since seeing his first Mitsubishi Evo VIII in 2003. He is almost entirely self taught mechanically, and as an inexperienced enthusiast always worked on his own vehicles, regardless of the difficulty, just to learn how to do it himself. Prior to becoming a freelance writer for the company, Kyle started his automotive performance career with Power Automedia as a shop technician, where he gleaned intimate knowledge of LS platforms and drag racing builds; then later joining the editorial team as the Staff Writer for EngineLabs And Turnology. Today, Kyle is an experienced EFI calibrator; hot rod builder; and motorsports technician living in the San Jose area. Kyle is a track junkie with lots of seat time. You can usually find him racing his Mitsubishi Evo X in local time attack and road race events.
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