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I designed the full vehicle suspension system geometry for the car that will compete in the 2025 season. The "geo" is the component from which all other parts on the car are based. The driveline geometry is based off of the suspension and chassis geometry and the chassis must line up with the suspension geometry to ensure the links, rack, and shocks will be able to mount to the car.
The 2023 car (TG19) was the first to implement the double A-arm with toe link and had very good handling characteristics on the tight maneuverability courses at competition, however, it lacked in jump and large obstacle performance. The 2024 car (TGXX) improved on this aspect of vehicle performance without notably degrading the maneuverability handling of the car. The goal of the 2025 car was to reduce steering effort in 4WD while maintaining the handling performance of previous cars.
The main way I intended to reduce steering effort was to reduce the kingpin offset. This is a dimension in the geometry that defines the distance between the kingpin axis (axis about which the front wheel pivots when steering) and the wheel center. There is a moment generated about this length that increases the force required to turn the steering wheel when torque is being transferred through the front wheels. Reducing the length of the kingpin offset reduces this force.
I performed testing on TGXX by reducing the kingpin offset using reduced wheel offset hubs. Qualitatively, there was a noticeable reduction in steering effort in 4WD. We also collected steering torque data using a steering column with a strain gauge rosette applied to it. The data showed an 8% lower steering torque on average with the reduced offset hubs.
The suspension component designers used the geometry to design the links, uprights, tie rods, and steering rack. The biggest challenge was getting all components to fit together in very tight space constraints. This required collaborating with other engineers to figure out where I needed to make changes to the geometry and where they could change their part to fit better with neighboring parts.
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