Interactive crossovers use a shim diameter larger than the shim stack clamp. The larger crossover diameter transfers force from the face shims directly into the high speed stack forcing high speed stack deflection before the crossover closes. Requiring the face shims to chase down a moving high speed stack softens the crossover closure event.

Shim ReStackor analysis of the interactive crossover tested by MXScandinavia on Thumper Talk produces a crossover closure velocity of 60 in/sec. However, the MXScandinavia dyno could only test to shaft speeds of 40 in/sec.

The test illustrates a typical frustration of dyno testing. At the velocity limit of the dyno no unusual behavior is observed. However, the crossover gap has not closed creating uncertainties in the high speed damping performance of the shock.

Shim ReStackor helps relive those uncertainties with the capability to compute high speed performance, evaluate crossover closure velocities and the effect of valve port flow restrictions that kick in at velocities beyond the limits of conventional dyno testing.

Crossover closes at shaft velocities beyond the dyno test speed capability