Design considerations for optimizing the wheel bearing outer ring bolt‑mounting pattern for reduced drag

Electric vehicles (EVs) place unique and demanding requirements on wheel bearing systems due to their increased vehicle mass, higher torque output, and the need for improved energy efficiency to maximize driving range. These factors elevate the loads transmitted through the bearing‐to‐knuckle joint, often necessitating higher clamp loads to maintain joint integrity. However, increased clamp loads can amplify wheel bearing outer ring distortion, leading to higher rotational drag and reduced bearing durability. Managing and minimizing outer ring distortion is therefore critical for EV wheel bearing design, as well as for high‑performance vehicles that experience extreme lateral loads at the hub‑to‑knuckle interface. This paper investigates key design considerations for optimizing the wheel bearing outer ring and its mounting interface to minimize distortion under elevated clamp loads. A comprehensive CAE‑based Design of Experiments (DOE) is conducted to evaluate the influence of various bolt mounting patterns—including rectangular, square, and trapezoidal configurations—and the alignment of the bolt pattern between the outer ring and knuckle. The study also compares the impacts of M12 and M14 fastener variants across multiple loading conditions representative of EV and high‑performance applications. The results identify geometric and interface design parameters that significantly reduce outer ring out‑of‑roundness, thereby lowering drag torque and improving long‑term bearing life.