Koni 8245.1442 Special Active Rear Shock Absorber 2016-2026 Mazda MX-5 Miata ND

The Koni 8245.1442 is a rear shock absorber built for the 2016 through 2026 Mazda MX-5 Miata ND, covering all trim levels and both the Roadster and RF body styles. Engineered in the Netherlands by Koni, the 8245.1442 uses Frequency Selective Damping (FSD) technology to automatically adapt damping force to road conditions without any manual adjustment. Unlike the front shock, the Koni Special Active 8245.1442 rear unit features two mounting clip positions that allow a small range of ride height adjustment at the rear axle, giving owners flexibility when matching ride height to their specific trim's original shock setup. The Koni 8245.1442 is covered by the Koni Lifetime Limited Warranty for the original purchaser in the United States and Canada.

Frequency Selective Damping (FSD) Technology

The Koni 8245.1442 uses Koni's patented Frequency Selective Damping system, which separates high-frequency, low-amplitude inputs from low-frequency, high-amplitude inputs at the valve level inside the shock. On smooth pavement and over fine road texture, the FSD valve opens a bypass channel that softens the damping force, absorbing small vibrations without transmitting harshness into the cabin. When the suspension encounters a sharper input such as a pothole, a mid-corner bump, or a hard braking event, the frequency of the input closes the bypass and the shock firms up immediately to control body motion. This automatic response happens continuously at each corner without driver input, dial adjustment, or electronic control. The result is a single fixed-rate shock that behaves like two separate tunes, keeping the MX-5 ND composed under hard driving while remaining compliant on daily roads.

Rear Ride Height and Clip Positions

The Koni 8245.1442 rear shock features two mounting clip positions that influence installed ride height at the rear axle. The upper clip position is intended for MX-5 ND trims originally equipped with the factory Bilstein OEM shock absorbers, which sit the car slightly higher due to their elevated nitrogen gas pressure. Because the Koni Special Active uses lower gas pressure than those OEM Bilstein units, the upper clip compensates for the pressure difference and brings the rear ride height closer to the Bilstein-equipped factory stance. The lower clip position targets trims equipped with the standard non-Bilstein OEM shock or owners who prefer a marginal drop below the stock non-Bilstein height. Selecting the correct clip position before installation ensures the rear stance is balanced with the front, where the companion front shock (part number 8245.1441) provides approximately 0.5 in. of drop relative to factory OEM.

Fitment

What's Included

• 1 x Koni Special Active Rear Shock Absorber (part number 8245.1442)
• Vehicle-specific mounting hardware is not included

Full Specifications

About Koni

Koni was founded in 1857 in Oud-Beijerland, the Netherlands, originally manufacturing steam-powered equipment before pivoting to vehicle shock absorbers in the 1930s. The company built its reputation supplying dampers to racing teams and premium vehicle manufacturers throughout Europe, establishing engineering credibility that carries through every product in its current lineup. Koni shock absorbers are produced at a purpose-built facility in the Netherlands and are engineered to meet or exceed OEM fitment tolerances. The Special Active line applies Koni's FSD valve technology to vehicles where ride quality and handling balance are equally critical, making the 8245.1442 a factory-upgrade-style replacement rather than a compromise. Koni remains an independent brand under the KYB Corporation umbrella and continues to develop damping technology for original equipment, motorsport, and aftermarket applications worldwide.

Frequently Asked Questions

What is Frequency Selective Damping and how does it work in the Koni 8245.1442?

Frequency Selective Damping (FSD) is a passive valve technology built into the piston of the 8245.1442. A secondary bypass channel inside the piston responds to the frequency and amplitude of suspension movement. At high frequencies and low amplitudes, the kind generated by road texture, tire noise, and minor surface irregularities, the bypass remains open and reduces overall damping force, giving the shock a soft, compliant character. At low frequencies and high amplitudes, the kind generated by body roll, braking dive, or hitting a pothole, the bypass closes and the shock operates at its full damping rate to control chassis motion. This all happens mechanically with no electronics, sensors, or driver input required.

What do the two clip positions on the Koni 8245.1442 do?

The two clip positions on the 8245.1442 adjust the installed length of the rear shock, which in turn affects rear ride height. The upper clip position is designed for MX-5 ND trims originally equipped with the factory Bilstein OEM shock absorbers. Because those Bilstein units use higher nitrogen gas pressure, they hold the rear of the car slightly higher than non-Bilstein variants. The Koni Special Active operates at lower gas pressure, so the upper clip compensates and keeps the rear height consistent with the Bilstein-equipped factory stance. The lower clip position is for trims with standard non-Bilstein OEM shocks or for owners who prefer a slight drop at the rear. Choose your clip position before installation and verify the resulting rear height is balanced with the front.

Is the Koni 8245.1442 sold as a single unit or as a pair?

The 8245.1442 is sold individually, meaning one shock absorber per package. To replace both rear shocks on your MX-5 ND, you will need to purchase two units of part number 8245.1442. The matching front shock is sold separately under part number 8245.1441. Replacing all four shocks at the same time is generally recommended to maintain balanced damping across all four corners.

Is the Koni 8245.1442 compatible with aftermarket lowering springs?

The Koni 8245.1442 is compatible with most aftermarket lowering springs designed for the Mazda MX-5 Miata ND platform. The clip position selection will determine the baseline rear ride height before any spring-related drop is applied. When pairing the 8245.1442 with lowering springs, use the lower clip position as your starting point if you want the maximum available drop, and verify that the total combined drop does not cause coil bind or compromise rear suspension travel. Consult the spring manufacturer's published specifications for the ND platform when calculating expected combined ride height.

How does the Koni 8245.1442 compare to the factory Bilstein shocks on some MX-5 ND trims?

Some MX-5 ND trims are equipped from the factory with Bilstein OEM rear shocks, which operate at higher nitrogen gas pressure and hold the rear of the car slightly higher than the standard non-Bilstein OEM shocks. The 8245.1442 uses lower gas pressure than the factory Bilstein units. To account for this, Koni engineered the upper clip position specifically for Bilstein-equipped trims so the installed ride height remains consistent with those vehicles' original stance. Neither shock is universally superior; the 8245.1442 offers FSD technology, which automatically varies damping in response to input frequency, a feature not present in the factory Bilstein OEM rear shocks.

Does installing the Koni 8245.1442 void my vehicle's factory warranty?

Under the Magnuson-Moss Warranty Act, a vehicle manufacturer cannot void your factory warranty solely because you installed an aftermarket part. The manufacturer would need to demonstrate that the aftermarket part directly caused the failure in question to deny a warranty claim on that specific component or system. Installing the Koni 8245.1442 does not automatically void your Mazda factory warranty. If you have specific concerns about warranty implications, consult with your Mazda dealer or review your warranty documentation before proceeding with installation.

Does the Koni 8245.1442 fit the MX-5 Miata RF (retractable fastback) body style?

Yes. The 8245.1442 fits both the Roadster (soft-top convertible) and the RF (retractable fastback) body styles of the 2016 through 2026 Mazda MX-5 Miata ND. The rear suspension geometry and mounting points are shared between the two body styles, so part number 8245.1442 covers both without any modification. While the RF carries additional weight from its retractable hardtop mechanism, this does not affect shock absorber fitment or part number applicability.

Do I need a wheel alignment after installing the Koni 8245.1442?

Yes, a four-wheel alignment is strongly recommended after installing the 8245.1442. Changes in rear ride height caused by the clip position selection can shift rear camber and toe values away from factory specifications. Misaligned rear geometry accelerates inside rear tire wear and can reduce straight-line stability and cornering balance. If you are installing both the front shock (8245.1441) and the 8245.1442 rear shock at the same time, complete all suspension work before scheduling the alignment appointment.

What warranty does the Koni 8245.1442 carry?

The 8245.1442 is covered by the Koni Lifetime Limited Warranty, which applies to the original purchaser in the United States and Canada. This warranty covers manufacturing defects for the life of the original purchaser's ownership of the vehicle on which the shocks were installed. The warranty does not transfer to subsequent owners. Contact Koni directly or visit the Koni website for full warranty terms, exclusions, and the claims process.