The Yost Autosport BMW M4: Part 1 – The Foundation of a Proper Race Car


The roll cage itself, on paper, is a simple N.A.S.A. Pro Racing spec roll cage but upon closer inspection you start to see all the thought that was really put into optimizing the cage design. For instance, the driver’s side door bar is shaped in a way to make it easier for drivers to get in and out of the car quickly during driver changes. There are extra braces for rear subframe and strut tower reinforcement and even the line of sight through the rear view mirror was taken into consideration when building this cage.


In this photo you can see the curved door bar for easier access during driver changes as well as the custom fender vents. Notice the hand-formed steel “scoop” made to smoothly direct the turbulent air out of the gaping hole in the fender. This piece is attached to the chassis itself and is super strong to be resilient with car-to-car contact and keeps the fender itself easily replaceable.

Outside of the work on the roll cage there was tons of other fabrication going on with the chassis as well. Most of it small odds & ends like making brackets for the air jacks, but some of it was pretty involved. One major check box on the list was clearing out an area and getting measurements off to Fuel Safe for a custom saddle-tank fuel cell. Fuel Safe was awesome to work with during this process and within a week we had a complete CAD file of our proposed fuel cell. With GenFab’s resources we were even able to take that CAD file and laser cut a cardboard mock-up fuel cell to the exact specifications for testing fitment with the roll cage.


Out with the old and in with the new. the floor that usually sits under the rear seats and above the factory fuel tank was cut out completely to make room for a new custom Fuel Safe fuel cell that will hold nearly 40 gallons of fuel.
Working with Fuel Safe's engineering team was awesome. We went back and forth with measurements on the available space we cleared out in the car to end up with a CAD file for a fuel cell that we could then use to laser cut a precise mock-up out of cardboard to check fitment.
Modern technology is awesome. The mock-up fuel cell in the car created by two teams of people who never even saw each other face to face.

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