The original bushing is made of rubber: it filters well, but deforms under load. When cornering or braking, the arm moves by a few millimeters and the geometry changes during the maneuver - this is the slack between the steering wheel and the wheels.

Polyurethane deforms much less: the connection becomes precise and repeatable, and the car responds in the same place every time. In return, more road noise and vibrations reach the cabin, especially when cold.