Evolve/Bilstein B6 Damptronic released

[Racer-X]

I used my stock ZCP springs along with new top hats. Car does sit at bit higher than it had perviously. Evolve themselves say it should settle back in, both in their video, by phone and here in the forum. So I guess opinions are just that and we shall see what happens over the coming months.

Originally Posted by M3SQRD

Did you install new springs or the MSS HAS kit? If not, then there’s no “settling period”. Depending on the spring manufacturer, you may get a little bit of spring settling with time; however, dampers don’t settle and, if they did, you wouldn’t see a change in ride height. Higher-end dampers use parts with much tighter clearances so there may be a small change in stiction after 100-200 miles BUT that doesn’t affect ride height. The Evolve/Bilstein B6, as well as the Bilstein B6, is a monotube damper with an internal nitrogen gas pressure chamber and a floating piston that separates the damper fluid from the gas. The chamber is necessary because as the piston rod moves into the damper, the internal volume of the piston rod increases and, therefore, the floating piston moves to accommodate this change in internal volume. Also, the gas pressure is required to reduce the possibility of cavitation (small air bubbles that form in front of the moving piston valve stack, minimizing/eliminating the damping force). The gas pressure is significant and creates a lifting force on the damper valve stack. This lifting force acts like a preloaded spring in parallel to the main spring. Your increase in ride height is due to the internal nitrogen gas lifting force which doesn’t change/settle with mileage (unless it fails). Additionally, the piston rod does not start to move/compress until the gas lifting force is exceeded, causing the damper to skip over (ride on top of) bumps rather than absorbing them.

TL;DR Ride height is increased because the B6 damper has significant internal nitrogen gas pressure but the gas pressure is required to allow the damper to consistently develop damping force. Putting mileage on the damper will not reduce the internal pressure or settle/reduce the ride height.

[M3SQRD]

Originally Posted by Racer-X

I used my stock ZCP springs along with new top hats. Car does sit at bit higher than it had perviously. Evolve themselves say it should settle back in, both in their video, by phone and here in the forum. So I guess opinions are just that and we shall see what happens over the coming months.

A damper is not a spring. It develops a force that’s proportional to the piston rod velocity relative to the damper body. Zero velocity, zero force. High-end dampers use very tight tolerances so the damper may have higher stiction when new and will reduce with wear (mileage); however, the damper still doesn’t carry a static load when the piston rod is not moving.

The B6 is a monotube damper which requires gas pressure to prevent cavitation from occurring when the piston rod valve stack moves through the hydraulic fluid in the damper. The nitrogen gas pressure does not wear in with mileage and it’s stored in an internal reservoir (may slowly leak over time but the damper has failed if it’s lost its gas charge). The gas pressure doesn’t change and the piston area doesn’t change so the gas lifting force doesn’t change.

So what in the damper would wear in with mileage that would cause the ride height to change? If you’re using new springs, which in your case you aren’t, then the ride height may change with mileage. It’s a bad damper if it loses gas pressure after just a little mileage.