If you want NO movement you could either glue the suspenstion in position, cut a small aluminum tube to the length you want and install it in place of a spring, or flatten both ends and drill holes through them and replace the suspenstion with the rigid tubes.
You could also try to duble up the springs, for example on one side use BOTH blue and yellow at the same time. Or you could cut a small aluminum tube that id the diameter of the spring but 1/2 the length and use it as a spacer with a spring at the same time.
I am sure there are other ways to do what you want without having to make a spring from scratch.
