I am designing the transfer case of the upcoming 21XT vehicle. The transfer case is a core drivetrain component with many purposes. It is a two-stage spur gear reduction that acts as the final drive reduction for the rear axles, shifts between two and four wheel drive, serves as the mounting point for the rear brake calipers, and must withstand suspension forces of close to 4000 lb and transfer these forces to the frame.

My main goals in designing this were to reduce overall mass, rotational inertia, and improve the overall packaging. 

I also had to accommodate the new vehicle architecture of having an off-center propshaft. By moving the propshaft several inches outboard, we could run it around the engine and seat rather than underneath them, lowering our center of mass by several inches and reducing the size of the frame. 

The gears were optimized by designing to an aggressive 5-hour lifespan using a torque-speed load spectra collected from on-car rear axle strain gauges in past endurance races. The tooth geometry analysis was performed in KISSSoft, and an Ansys model was used to analyze gear webbing geometry.

Ansys studies of each of the five shafts in the transfer case were independently created, applying loads from the gears, CVT, and the suspension loads from the rear axles. The loads on the bearings were probed and then used to create a 20-scenario assembly-level study on the case using Ansys.

Currently, these photographs are of last year's transfer case (designed by Zatara Nepomuceno). Though there are some major differences to my design, there is a lot of shared design heritage and part features. I'll update this as parts for the new transfer case are manufactured!