During the Spring of 2022, I took on a project for Terps Racing – University of Maryland’s Society of Automotive Engineers (SAE) Off-Road team. While testing our vehicle, we noticed that our turning radius was wider than anticipated and that the car would struggle in the maneuverability event. To combat this issue, I researched, designed, and manufactured Terps Racing’s first removable rear sway bar.
The purpose of the sway bar, which is also known as an anti-roll bar, is to connect the suspension components on each side of the car, limiting each tire’s ability to move independently. A sharp turn is performed by shifting the weight of the car from one side to the other. If each tire is moving independently, we can expect one tire to rise, and the other to drop. This can create a large turn radius, or worse, it can cause the car to roll over. With a sway bar, however, each side’s suspension is connected, thus stabilizing the car, and creating a tighter turn radius.
Though the sway bar improves steering, it adds weight to the car. As SAE limits each team to a 10-horsepower engine, every pound matters. Understanding this, I began brainstorming ways to make the sway bar removable. For certain events (acceleration, endurance, and suspension), the car would perform better without the sway bar. The solution was to use a hex insert to fasten the bar to its connecting piece. See the picture below for a visual reference. By using this hex insert, the sway bar could be removed by simply loosening a singular bolt. This allowed the team to quickly remove the sway bar depending on the event.
The most important lesson I learned in this project was the importance of DFM. At the time, I had little to no manufacturing experience. By designing this part to be as simple as possible, while still being functional, we were able to manufacture and assemble this part quickly. The part was made almost entirely out of scrap materials found in the machine shop, and significantly improved the car's performance.
The picture on the right shows a closer look at the hex insert discussed above. This hex insert, which was bought via McMaster-Carr’s website, will provide material for the bolt to thread into. This ensures a secure, but not permanent connection.
The other end, however, is a permanent connection. Pictured to the right is a closer look at the side that requires welding. In addition, the component highlighted in blue is a bushing. This bushing is made of brass and was manufactured using a lathe. The bushing was carefully dimensioned to be a press-fit into the chassis tube. This ensures that the bar is held stable to the chassis.
This picture shows the manufactured sway bar (painted yellow) connected to the H-Arm. As our chassis tubes are hollow, the best way to mount this component was by running the bar through the chassis. Not only did this help to stabilize the sway bar, but it also gave clearance to perform maintenance on the powertrain.