As the title of this post reveals, I am working on a simple suspension kinematics tool in excel, which is able to calculate the position of each hardpoint, basing on the defined suspension movement and all the most important metrics.

For now i am only focusing on double wishbones, as this is the scheme which is mostly used on the race cars I am interested in, but it should be pretty easy to adapt it to be used for a generic five links geometry, in the future.

The method I used is based on the intersections of spheres in space. Each moving point of a suspension is derived as the intersection of three spheres, with the center of each seating on an hardpoint whose position is fixed or has been already identified in a previous step; the radius of the sphere is either a link length or the distance between the point we want to locate and another point of the same component (see for example a wishbone or the upright).

For the very first point (namely the outer point of the lower wishbone, in my case) we can use two close points (for example the two connection points of the same wishbone to the chassis) and a reference point, which can be placed everywhere and will be afterward used also as the input for each suspension movement. In my case, this point will only move in z (vertical direction), as this is all what we need to simulate how a suspension moves.

To read more about the suspension kinematics tool, check out the DrRacing blog posts –

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