Upper Steering System for VM26E EV
Upper Steering System for VM26E EV
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Project Summary
After the 2025 season, it was determined that the upper steering system on the VM25E suffered from excessive backlash, leading to inconsistency and a lack of steering response. To mitigate this, we decided to eliminate the bevel box and switch to universal joints, which significantly reduce backlash while maintaining constant velocity steering. In addition to designing the joint/shaft geometry, I also designed the steering column supports, bearing housing, and the input shaft.
Design Requirements
Load Capacity: Must withstand worst-case scenario load in all directions
CV Steering: Maintain constant velocity steering
Rules Compliance: Must adhere to cockpit template rules and other FSAE regulations
Servicability: Allow for easy disassembly, maintenance, and part replacement
Project Details
Year: 2025
Role: Driver Interface & Brakes Member/Lead
Duration: 3 months
Software: Fusion 360, Fusion 360 FEA
Materials: Various
Load Analysis
I used human dynamometer data and performed hand calculations to determine the maximum load case in each direction.
Axial Load
Formulated maximum axial load based on FSAE judge advice and cockpit force data
Radial Load
Calculated maximum radial load based on peak braking acceleration and cockpit force data
Steering Torque
Computed maximum steering torque load case based on human cockpit force data and human dynamometer data
Bearing Selection
Tapered roller bearings were selected due to their ability to handle both radial and axial loading
FEA Simulation
I utilized Fusion 360 FEA to simulate the maximum load case in each direction simultaneously, with the welds in the supports modeled by changing the material properties to account for heat-affected zones (HAZ's).
Shaft Geometry
To maintain constant velocity steering while considering steering rack placement, both spatial angles of the chosen double u-joint must be equal. The joint and shaft placement ensures template compliance and CV steering.
Full Upper Steering Assembly
Bolt-through connections are used for the assembly of shafts/joints for ease of maintenance and assembly. A disk spring is used between the input shaft and the front tapered roller bearing for reliable preload.
Validation and Final Results
Minimum safety factor of 1.366 during worst-case loading
Potential 5-10% weight reduction
CV steering maintained while passing FSAE template requirements
Will be manufactured for the upcoming VM26E car
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