Скачать или смотреть MBX7R Eco Standard Spring Vs. Dual Rate Springs

(Disclaimer: this video made in Final Cut Pro, b/c I hated the demo of Premier elements. Don't assume that because previous videos have the Adobe Premier banner through the middle, that I must have liked it and decided to continue using it.)

In this video I am comparing the standard suspension to a modification where I installed small springs inside the shocks that create a dual rate effect.

What is very clear on the bench, and which can also be seen on my dyno, is that the dual rate springs allow the vehicle to return to it's static ride height much quicker. In the split screen comparison, it is clear that the dual rate springs allow the chassis to settle after 1/2 a rotation of the dyno wheels, compared to the standard springs, where the chassis has not yet settled after a full rotation of the dyno wheels.


The way these dual rate springs work is that when the vehicle is at ride height or when the shocks are compressed, the standard spring is supporting the vehicle as usual. The inner springs are just floating inside the shock. But on rebound, when the suspension rebounds past the static ride height, the inner spring is compressed. The effect is that the spring rate of the main spring drops off rapidly. At full droop, there is almost no force pushing the tires down.

There is a lot of adjustability with springs like this, depending on what you want to achieve. The springs I chose were intended to cancel out the spring's force at full droop of the suspension. If I chose a softer spring, I would have a little more spring force at full droop, and likewise, if I chose a stronger spring, I would actually limit suspension droop.

To spec out the springs, I first had to know the spring rate of the main springs. And then I measured to find out how compressed the spring is at static ride height, and also at full droop. I need to know how much space there is inside the shock, between the bottom of the piston and the bottom of the shock body. Ideally my spring should match this length.

To determine what spring rate I needed, I made a spreadsheet that showed the force the spring exerts between full droop and static ride height. Then I experimented with what spring rate I would need for the inner spring to cancel out the force of the main spring at full suspension droop.

Intuitively it would seem like a very strong spring would be needed, but as the suspension rebounds, the main spring is progressively applying less force. I only need to cancel the spring's force when it is extended, when it exerts the least amount of force.

This project is quite a bit more complex than just buying a spring from the company that makes my kit. If you try it, it might take a couple tries; it took me two tries to get it right. To get the right result requires taking measurements to determine the correct spring strength, spring length, and compressed spring length. It isn't terribly difficult, but it requires a lot more work than normal "upgrades" to an RC.