#FCMElite #TeamLowPressure #RippleReducer #TeamNoJitter
The nitrogen gas pressure inside a standard monotube damper is necessary to keep the oil column supported so the shock piston can cycle through the oil and dissipate heat. However, too much ni…
#FCMElite #TeamLowPressure #RippleReducer #TeamNoJitter
The nitrogen gas pressure inside a standard monotube damper is necessary to keep the oil column supported so the shock piston can cycle through the oil and dissipate heat. However, too much nitrogen pressure creates excessive initial opening force - also knows as 'JERK' - which compromises the suspension's ability to track small surface changes as well as to keep the tires in contact with rough road surfaces. Jerk is a property that suspension engineers go to great lengths to eliminate or minimize to improve both ride quality and ultimate tire grip.
To understand these behaviors, it's important to realize introducing a gas charge at the bottom of the monotube damper creates some ... interesting results. In electrical circuit terms, you have added a capacitance in series with a resistance. This creates a delay in the system response while the capacitor charges. That's what my recollection of my circuit's analysis class and common sense tell me!
For the suspension analogy, this gas spring acts to block the smooth opening of the damper (while it also make it close or extend more easily). You can see this as I attempt to cycle the damper with 0 psi fill pressure, then 200 psi and finally 400 psi. The damper becomes harder and harder to open and also to cycle back and forth over very small movements. I do my best to demonstrate some of these behaviors in this and subsequent videos.
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The gas spring creates an undesirable behavior within the damper - a frequency-dependent and amplitude-dependent spring. This is where the simple capacitor/resistor analogy becomes insufficient (any EE's please clarify my understanding if needed). The damper gas spring can increase in rate as the shock shaft goes farther into the damper. Also, if the nitrogen chamber is too small, the ramp in spring rate may be dramatic.
So, what may seem a simple 'preload' in a static situation ('you can treat it like spring preload') bec..
