I've been using VRCPhysBones for dynamic elements such as antennas and mud flaps on drivable vehicles since November, 2025 without issues, but some VRChat client update in January 2026 suddenly broke VRCPhysBones attached to vehicles in worlds, causing violent shaking when driving.

PhysBones still behave normally in Unity Editor when testing using ClientSim, but when in game, all bones begin to violently shake back and forth, as if fighting against the linear motion of the vehicle.

The issue was first discovered in a world that had been fully functional for weeks, when suddenly in January the stuttering began in all versions of the world.

The vehicles use Rigidbody and VRCObjectSync at the root and Unity WheelColliders for wheels.