In our last story, we were redesigning the steering knuckle/upright for the 2019 season on Dai Yoshihara’s Turn 14 Formula Drift BR-Z. Our design goals were to keep the tires flatter on the ground with reduced camber change over the cars turning lock, increase the amount of steering angle, improve self-steer, quicken the steering ratio, reduce stress on the power steering pump and reduce chassis geometric weight jacking under extreme steering angles.
In part one we had made a parametric stick model of our upright with all mounting and pivoting points represented and made a simple adjustable 3D printed part that we could fit on the actual car, cycle and adjust to quickly experiment with configuration changes in real life as a tool and visual aid. With this, we quickly settled on the geometry we wanted on the real part.
With all the hard mounting points and pivot locations identified, Chis Eimer of Eimer Engineering went ahead and drew up the upright fully in solid works. You can see some of the cool stuff in the design like the different pills used to adjust the Ackerman angle by changing the tie rod pick up point.
The upright is made of 3/16″ thick 4130 chromoly plate. It is arranged so the upright is hollow in construction with a large cross-section so it ends up being much stronger but lighter than the stock part. The plate is laser cut into shape and tig welded together. Note how the pieces interlock to make the assembly of the part easier and more precise to fabricate.
Here is the actual fabricated part as installed on the car. You can see its large boxed cross-section thin wall construction. We feel that our method of building the uprights on this car is somewhat innovative, at least in the drift world and we can deliver high strength, accurate but lightweight parts with very little tooling cost.