ELI5: How does car suspension work?

To understand how suspension technology works, we thought it best to follow the old adage and stand on the shoulders of giants. As our Chief Test Engineer, Joakim Rydholm, has spent his entire career learning everything there is to know about cars (so you don’t have to), we are leaving you in very capable hands.Let’s begin with a little crash course in suspension system physics. A bump in the road will force the wheel to move upwards. But thanks to gravity (and rebound damping), the wheel will be pulled down toward the road surface once it’s passed the bump. At Polestar, we want our cars to travel horizontally, not vertically (at least not yet), so we need a system that can absorb the energy of the vertically accelerated wheel, allowing for a smooth ride over bumpy roads. This is where the suspension system comes in.Step one is to absorb the energy. This is done by the springs. The stiffness of the springs affects how the car reacts when being driven. For example, luxury cars tend to have loose springs allowing for a soft and comfortable ride. However, this also leads to a less reactive car as they tend to sway and roll during cornering. Tightly sprung springs found on sports cars are a lot less forgiving on bumpy roads, but they reduce body movement and can therefore be driven much more aggressively. “But if you drove an F1 car on a public road for more than 5km you’d probably never want to sit in a car again,” says Joakim Rydholm.But springs are not enough. “If we only relied on springs, hitting a bump would result in the car swinging up and down like a rocking chair until all the energy had dissipated,” Joakim notes. This leads us to the next puzzle piece: the dampers.

The easiest way to explain dampers is that they eat energy. The slightly more complicated way to explain it is that they turn the energy of suspension movement into heat energy that can be dissipated through hydraulic fluid. In short, springs ensure that the car can bounce over a bump in the road, and dampers make sure that the car stops bouncing once it has passed the bump.Now that we’re comfortable with the concepts of springs and dampers let’s move on to the unique suspension technology inside a Polestar. Remember the difference between luxury and sports cars that we discussed earlier? If you want a comfortable ride where you almost float over bumps and potholes, you pick a car with soft suspension. On the other hand, if you want a reactive car that you can bend around tight corners and accelerate rapidly, a car with stiffer suspension is your best option.But what if you don’t want to pick? What if you want both comfort and performance?The Polestar performance pack comes with Öhlins dual flow valve (DFV) dampers. With the turn of a knob, you can literally choose your own suspension settings in the comfort of your own garage. “The damper affects the whole performance of the car – handling, steering and comfort. With these dampers you can tune your car exactly how you want it,” says Joakim Rydholm.This kind of unique control allows for extreme optimisation. Let’s say you’re setting out on a longer road trip; loosening up the dampers will have you gliding down the motorway like Aladdin on his magic carpet. On the other hand, if you find yourself on a winding country road that allows for more speed and curves, you tighten up the dampers and suddenly you have your sports car back. It’s that simple.The Polestar 2 with performance pack offers you a tailored suit that you can refit as much as you want, wherever you are. This technology does not require any suspension of disbelief. Just a belief in the power of suspension.