A general shim stack tuning misconception is high speed damping is controlled by the high speed stack. That creates the perception removing a couple of shims from the high speed stack will “loosen-up” high speed damping and have little effect on damping force elsewhere.

Dyno testing and Shim ReStackor calculations show that approach does not work.

Valving Logic provides a dyno test example on Thumper Talk.

The rmz250-248 shim stack runs a full stack taper. The rmz250-152 configuration completely removes the high speed stack with the expectation of “loosening-up” high speed damping.

Dyno tests of the two configurations shows no difference in high speed damping (data points). Shim ReStackor calculations (lines) show the same thing.

High speed damping can softened by tuning the shim stack with a preloaded ring-shim (more).

High speed stack stiffness has little influance on high speed damping force measured on the dyno