Development

First Prototype

First PrototypeOur first prototype car had double a-arm suspension for the inner roll suspension and a strut suspension for the outer dive suspension.  Steering linkage was left identical to a conventional rack & pinion on a double a-arm car so was the tie rods for the stabilizer links in rear suspension.  The suspension was set for minimum camber change with respect to the ground for both dive and roll motions. 

On the front suspension design wheel camber stayed almost fixed with respect to the ground and this allowed for almost no toe change due to steering linkage during jounce or roll.  With this type of conventional steering linkage on Sacli suspension, cambering the tires into the turn would lead to toe change during roll (roll steer).  The strut design had the strut axis forward of the wheel axis and the trail distance was higher than desirable even if castor angle was very low.  Sacli suspension doesn’t need castor angle like a conventional suspension design does, since it has better camber recovery.   However the larger trail distance also meant larger scrub radius, which wasn’t desirable.

Front suspension 1st prototypeOn the rear suspension design the wheel camber also stayed almost fixed with respect to the ground.  Rear suspension stabilizer rod geometry was different from the steering linkage and rear suspension had small amount of roll steer.  Rear wheels steered into the turn as the sprung mass rolled out. [Click image to enlarge.]

Our first prototype was a direct bolt on conversion from a typical double a-arm FSAE car.  This conversion was done by simply replacing the a-arms, chassis pick up points for a-arms, replacing the upright with strut assemblies and adding a lock link that connects the existing bell cranks to each other.  The car weighed just under 500 lbs and had about 45/55 front to rear weight distribution. [Click image to enlarge.]

Overview - real