Split crossovers (linky sample apps) use two shims to form the crossover gap. Split shims smooth the bend radius at the crossover shoulder and help prevent kinking of the face shims on the sharp shoulder of a single crossover shim.
Valving Logic dyno testing of an rmz450 used a spit shim crossover with a crossover gap of 0.3mm. The large gap coupled with the stiff low speed stack produces a crossover closure velocity of 120 in/sec, roughly twice the dyno test speed capability.
The data illustrates a frequent dyno test frustration. At the limit of the dyno the crossover gap has not closed. Damping force will increase after the crossover gap closes, but there is no way to estimate the high speed performance from the data obtained.
The capability of Shim ReStackor to compute high speed performance helps to relieve those uncertainties and determine the effect of high speed crossover closures and valve port flow restrictions that kick in at high speed.
