Chassis: Square One
The chassis of any car is what actually makes the car. Like a skeleton holds the human body in its shape, the chassis holds the car together. It’s like the car’s backbone, so-to-speak. Everything on the car is attached to the chassis, and, for that reason the chassis must have a very solid, strong, and rigid design. Below is a picture of our chassis before everything gets put on the car.
Believe it or not, our chassis actually comes in a box as a collection of tubes from VR3 Engineering that could fit in the back of your supped-up Camry. We weld it all together and BOOM chassis. While the manufacturing process may be one of the simplest on the car, the design is one of the most complicated. Per the FSAE rules, the chassis must meet certain requirements including rigidity, triangulation, and available space for the driver. All of these must be met while using the lightest design possible to keep the weight of the car down to a minimum.
How the chassis is designed greatly affects how the car handles. For the purposes of this discussion, think of the chassis as an ultra-stiff spring. While you may not be able to see the chassis move as it goes around the track from the stands, the chassis is moving.
Before we get to our car, let’s talk about street vehicles. Most of your sedans, coupes, vans, etc. will have an aluminum chassis. Aluminum is much lighter than traditional steel, which helps manufacturers get better gas mileage and use smaller engines. Your trucks, heavier SUVs, and similar vehicles have been using steel frames until recently. Ford’s newest F-150 pickup is built on an aircraft-grade aluminum frame, making it much, much lighter than the steel frame they were using. While lighter is better for racecars, a pickup is not meant to be on the track, so the new design was met with heavy criticism over whether or not the truck would fail under heavy load. After the first few months on the street, the F-150 is actually performing quite well.
Long story, short: steel is strong, rigid, and heavy; aluminum is light, bendy (that’s a technical term), and weaker.
So with racecars, to get the best handling, you want the car to be as stiff as possible. Since the chassis is a spring, that spring can’t move. Keep in mind that this includes not only the traditional forward and back motion but the twisting of the chassis as well. This can be done several ways which would take a very long time to explain, so here’s a picture of the ’15 chassis.
This chassis met all the requirements set by the FSAE rules. These rules keep the chassis stiff enough to shake you around a bit as you go around the track, but the ultimate goal here is to have your eyeballs rattle around in your head. Teams have a hard time with the triangulation in the front, which requires an upper, middle, and lower member extending from the bulkhead to about midway through the chassis (as of this posting).
So there you have it! There’s not a whole lot to say about the chassis and what it does, even though the entire car is built off of it. There are many designs out there that SAE teams use, from steel tube frames (also called spaceframes) to carbon fiber monocoques (where the body and chassis are the same – more on that in the Body post). As long as the design is light, strong, and rigid, you’re all set!
- K
