Polyurethane bushings for BMW 5 Series E39 / control arm bushing - front axle subframe housing — TA Technix

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

Polyurethane deforms much less: the connection becomes precise and repeatable, and the car responds at the same point every time. In return, more road noise and vibrations are transmitted into the cabin, especially when cold.