Diff Brackets

A crucial part of any racecar is having a powertrain that won’t explode on takeoff. Designing this requires some really careful attention to detail and ensuring that both the models and the simulations aren’t lying to you as an engineer.

These new brackets hold the differential to the car. The diff receives load from the engine via the drive chain and applies it to the two rear wheels, all the while allowing some relative slip between the two wheels so that turning isn’t impossible. I’ve designed these brackets to be made out of 7075 Aluminum, a high strength, low-weight alloy. The design is based off a concept known as “trussed webbing”, which allows for high strength with minimal material by placing most of the material in only the load bearing plane. To prevent buckling from occurring, trusses are implemented to give strength to the thin webbing elements.

I first modeled the bracket in solidworks, generating the beautiful stress profiles seen below.

Solidworks Simulation FEA of stress profile in a loaded configuration

Many, many design iterations later, a successful model was developed and Keith Durand, the grad student responsible for FSAE even happening these days, machined up the marvelous little beauties. Here they are in full glory.

A view showing the finished brackets with trussing

Here’s an image showing the clamping zone up close. This region’s fascinating as the inner circle is actually a clamp that holds the bearing on the differential. The small hole below holds a nut, and a bolt comes from the end, squeezing the circle and pre-loading the bearing properly.