Home: Triton Racing

Triton Racing

Swappable Independent Rear Suspension Project

Spring 2019 MAE 156B

University of California, San Diego

Roland Ho

Elliot Johnston

Cameron Wilkinson

Yukai Zhang

Triton Racing FSAE provides students with a platform to learn and experience the engineering process. Every year, the team builds a new formula-style race car from scratch and competes against other universities in Lincoln, NE. Triton Racing is one of two universities to use a dependent de Dion rear suspension since 2015. Though the team has had large success using this platform -- even rising to become the highest ranked FSAE team in California -- the design decision to use the de Dion rear suspension still rests on a limited and rather untested theory. There is a need to quantify and validate the effectiveness of the de Dion in an FSAE environment. This project aims to create a platform for testing the de Dion directly against the more modern, independent rear suspension (IRS). If deemed to be the superior system, the IRS developed in this project will become the new platform for many new Triton Racing vehicles to come.

Triton Racing Team Photo 2018

Crash Course Comparison of Independent VS. Dependent Rear Suspensions:

The de Dion is a sophisticated variant of the traditional dependent rear suspension. Since the two rear wheels are rigidly connected to each other by the de Dion axle, any disturbances on one side of the car would get transmitted to the other side, which makes the rear end of the car unstable on uneven or bumpy surfaces. The relatively high rear suspension roll center also encourages undesirable jacking under hard cornering. Therefore, the de Dion Rear Suspension is considered outdated by modern standards, and the Independent Rear Suspension (IRS) has come to dominate the racing world with its lower unsprung mass, lower roll center, and the ability to keep wheel disturbances isolated from the other wheel. However, the FSAE Lincoln competition that Triton Racing competes at is held at Lincoln Airpark, a mostly flat wide-open airstrip. Therefore, the frequency that the wheels encounter disturbances is very low, which is the main reason why Triton Racing decided to use the de Dion Rear Suspension. One advantage the de Dion has is its ability to set and maintain a constant wheel camber when on a flat track no matter how much the suspension is deflected and how much the chassis rolls. Theoretically the tires can retain the maximum contact patch with the ground at all times thus it has the potential to provide more lateral and longitudinal traction for faster lap times. With an Independent Rear Suspension, the camber of the tire is affected by the movement of the chassis and suspension, which makes it harder to maintain an optimal contact patch between the tires and the ground when the car is moving.

TR18's de Dion Rear Suspension

Objective:

The main goal of the project is to create a retrofit IRS for an older car which can be easily swapped with the original to facilitate direct comparisons between suspension types.

Final Design:

The final design of the IRS assembly consists of three subassemblies: 1. Subframe Assembly, 2. Suspension Control Arm Assembly (Wishbone) and 3. Upright Assembly. The subframe assembly is bolted onto the chassis and the engine and it provides the inboard attachments points for the suspension control arm assembly. The suspension control arm assembly controls the suspension and wheel movement and the upright assembly retains the wheel hub and wheel bearings that allow the wheels to rotate. None of the components are permanently mounted to the vehicle, which allows for quick swaps between different suspension setups.

Final Design Installed on TR18