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The Impact of Wheel Rotations to the Lateral Runout of a Hybrid Material or Dimensionally Reduced Wheel Bearing Flange
ISSN: 0148-7191, e-ISSN: 2688-3627
Published October 11, 2021 by SAE International in United States
The automotive industry is continuously striving for lower mass components including wheel bearings. A typical wheel bearing is mostly steel, including both the wheel and knuckle mounting flanges. Mass optimizations through cross section reductions and/or the use of alternative materials is now part of component development. While bearing component performance is varied thru analysis and testing by the supplier, Vehicle integration impacts over time also need to be comprehended. In a recent new vehicle architecture, the wheel bearing flange was optimized for low mass. The wheel mount flange thickness was reduced, and holes were added for further optimization. While the design met all the supplier and OEM’s component level specifications, vehicle testing revealed that the wheel bearing developed high assembled lateral runout (ALRO) when the wheels were rotated multiple times during a durability schedule. Excessive ALRO will generate high disc thickness variation (DTV) which will lead to pulsation or judder complaints. The root cause of the vehicle level judder was determined to be due to excessive ALRO and DTV in the brake corner. The major contributor to this LRO issue was the wheel bearing flange distortion that occurred with use and multiple tire/wheel rotations. During the durability testing regional differences were observed on the same architecture. Regions that performed more tire rotations and other maintenance observed the vehicle judder, while the other region did less maintenance did not. In order to better understand the bearing flange effect on ALRO, a lab evaluation was performed. Several wheel bearing flange designs were evaluated, including wheel flange designs with different flange thicknesses and versions with and without weight savings holes. Additionally, bearings with an aluminum/steel wheel flange were tested.