Baja Seat - Baja SAE
Overview
September 2022 - May 2023
CAD • Composites • Baja SAE
I joined Northwestern University Baja during Fall quarter of my freshman year, where I chose to tackle the difficult task of making a lightweight yet comfortable seat for the 2022-23 car. Northwestern Baja is an off-road racing team that races at Baja Society of Automotive Engineers collegiate competitions, where teams compete in a variety of events ranging from dynamic maneuverability courses to a 4 hour long endurance race designed to break vehicles.
Initial Design
A uncut seat was fiberglass seat was already selected by my sub-team lead prior to me joining the team. With this material already selected, I had to create a model of the seat to then cut out of and shape to make the final design.
To come up with the shape, I consulted a variety of members who had driven the previous year’s car and taken measurements from our largest and smallest members. One thing that was mentioned a lot was bruising around the shoulders from the concentrated forces in between the seat belt and the seat, so I set out to model something that could help spread the load.
I used Solidworks to create the model using some of the measurements I took from various members. The primary feature of this seat design was the side bolsters, similar to that of a racing bucket seat. The idea was to envelop the driver in both the lateral and rear direction to help reduce bruising on the driver’s shoulder. Beyond that, the seatbelt holes were added to line up frame members, per the official SAE rulebook,
If you look at the model and the photos of the final seat, you will quickly notice that they are of drastically different shapes, as the large part of the side bolsters have been removed. This was due to it interfering with some drivers arms, which would run into the bottom corner of the side bolster when making a sharp turn. Because of this, they were eventually removed, which no longer caused the bolsters to interfere with them driving. Of course, this then meant that the original shoulder bruising issue could potentially return.
Padding System
The next step was to create a padding system for the seat, as no one wants to sit on stiff fiberglass when jumping off a ramp. SAE mandated that all padding should be made of closed cell foam, thus EVA foam in the form of flooring mats was chosen, as it was affordable, weather resistant, and relatively light.
To mount the foam, I had the idea of sticking two large strips of velcro on the back and bottom surfaces of the seat, as this allowed me to then attach the individual foam modules onto the seat at any position, depending on the body/height of the driver. This is especially important as the driver’s shoulders cannot be below the start of the seatbelt. This meant that for shorter members, a thicker bottom pad could be added to be rule compliant, which could then be swapped out for a thinner pad when a taller driver was driving.
In addition, velcro was weather resistant and could work in the freezing temperatures of Upper Peninsula Michigan during the winter months, where we raced every year at the Winter Baja. Likewise, I made many different foam modules so that drivers of different shapes and sizes were all able to race.