Carefully designed by KONI, this shock absorber kit provides exceptional handling properties and road-holding. 21004123 BMW E90 E91 E92 AWD Models .
What are Koni FSD Shock Absorbers?
Koni's Frequency Selective Damping (FSD) technology is specifically designed to combine the ultimate in comfort and road-holding.
Normally when you shop for shock absorbers, you need to choose between comfort and road-holding performance. Not so with the KONI FSD! The FSD technology was designed and patented to end the compromise between comfort and road-holding performance. FSD operates as a fully hydraulic and frequency selective shock absorber, and is an economical and effective solution to improving a car's handling performance. ;
FSD Works in 2 Frequency Areas:
- For comfort, with the suspension moving in a high frequency area (+10 Hz), asking for low damping forces
- For handling, with the suspension moving in a low frequency area (+1 Hz), asking for high damping forces
If you are able to change the damping force level in relation to the frequency of the movement, you create the possibility to solve the conflict in terms of comfort and handling ever present in conventional dampers. FSD technology does just that!
How it Works
In standard shock absorbers, the main damping characteristic is defined by the oil flow going through a piston assembly. Combining this with the FSD feature, KONI added a special valve, which controls an oil flow parallel to the one going through the piston rod. This parallel oil flow is closed by the FSD feature, giving a rise in damping force almost linear to the time that the piston is moving in one direction.
In lay man's terms, FSD features a hydraulic amplifier that delays the build up of pressure. As an integrated component of the hydraulic valve system inside the shock absorber, no additional cables, sensors or any other electronic devices are needed to operate an FSD shock absorber! FSD is the simplest and most economic way to significantly improve the ride and driving characteristics of every car.
- E90 3-Series: xi, xd, xDrive. Including M-Technik)
- E91 3-Series: xi, xd, xDrive. Including M-Technik)
- E92 3-Series: xi, xd, xDrive. Including M-Technik)
Note: To install the FSD struts, we include a special McPherson strut insert that gets bolted into the factory strut housing (requires cutting the factory strut housing top and removing old internal parts).