Development

Next Step

Our testing showed that the higher we locate the dive suspension roll center the better Sacli suspension works.  This improvement would continue until roll center for the dive suspension gets high enough to have jacking issues.  A vehicle with its dive suspension roll center higher would lose less camber due to dive suspension roll during cornering.  This dive suspension would roll less because of its shorter moment arm length.  At the same time a dive suspension with a higher roll center would allow for a double a-arm design that has very little camber change during jounce.  Using the double a-arm design would also allow for minimizing the roll center migration.

These factors would increase the overall camber recovery at the wheel during cornering and minimize the camber change during jounce.  This set up would also be stable since the dive suspension roll center migration can be minimized.  The height of the dive roll center location would be limited based on the jacking forces, CG height and roll suspension roll center location.

Next Sacli suspension prototype would most likely use double a-arm suspension for both the roll and dive suspension due to double a-arm designs’ good camber and roll center control.  This would allow for the design to meet the goals mentioned in the above paragraphs.

Alternatively the next prototype could use a swing arm suspension design for the roll suspension and a double a-arm suspension design for the dive suspension to achieve similar results, with little sacrifice in camber recovery.  The benefit here would be a simpler design.

A double a-arm to strut design like the first prototype will always be subject to roll center migration due to the strut inclination change.  Thus it will be limited in performance.  However, if another try was to be made with such a design, the dive suspension roll center would be made higher with reverse king pin inclination on the struts.  This combined with lower roll suspension roll center would make a car that performs better, although not as well as an a-arm to a-arm car.

Also, the lock link for the next prototype would most likely be an hydraulic link. This link would connect the left and right dampers such that they can’t compress or extend at the same time. This design allows for better packaging options. The hydraulic lock link replaces the push rod, bell crank and the mechanical lock link

So far, all development has been done without relying on the speed selective damping features that are to be controlling roll and dive suspensions separately.  The Sacli suspension is performing quite well even before we add one of its most important control tools; the speed selective damping that distinguishes low speed roll suspension motion from the high speed dive suspension motion.

At this point it seems that the next Sacli suspension system with the above said geometry and proper spring and damping curves for roll suspension and dive suspension would quite exceed the wheel and ride control capabilities of conventional suspension systems.