Q: Why replace the factory Model 3 arms if they already work?

Tesla’s rear arms are stamped steel with soft rubber compliance bushings, chosen to keep noise and vibration low for a mass-market car. Under hard cornering or braking those bushings compress and twist, letting the wheel move in ways the geometry was not meant to allow. The result is lost motion at the contact patch and inconsistent toe and camber mid-corner. Rubber also degrades with heat and miles, so slop grows over time.