and hard springs result in better handling. Thanks for the explaining the ‘why’ so well!
I’ve said for a long time that soft suspensions do exactly what this guy says when it comes to uneven roads. On a track, when the pavement is perfect, then it’d be fine to have a harder suspension, but anywhere else, you’re better off with a softer one.
Just got some reinforcement for what I have said for years! Yay!
Ok this KONI FSD system seems to make sense after this video together with some stiffer swaybar setup. Thanks!
I was always a fan of undersprung, overdampened setups. It’s usually in high end German luxury cars because you get a smooth ride with minimal bounce.
what about progressive springs?
So can this relate to a computer controlled air suspension system?
Ok first, the point of a suspension is to keep the tire in contact with the road. To this pursuit you must balance suspension travel with suspension stiffness. The reason for this need to balance is that as the cars weight shifts the suspension geometry, balance, and tire load. Essentially when you take a turn the force applied to the car isn’t actually acting on the center of mass. It’s acting below and to the side of the center of mass. As such what is actually happening is that the frictional force between the tire and the road is generating a torque on the car. This torque attempts to rotate the car around the center of mass. This lifts the inside tires off the ground and drives the outside front tire into the ground. The springs push the tires into the ground and counter act some of the rotation by applying their own torque to the center of mass. Now the stiffer the springs are the more they press the lifted tires into the ground and counteract the rotation of the center of mass. As such there is more weight on the other three wheels and thus they have more mechanical grip (IE friction), but this isn’t all, the suspension works best when everything is at a certain angle. The stiffer spring rate keeps this from changing as drastically. This also means that the whole car is easier to upset as drastic changes in road surface actually are translated to the whole chassis causing it to move rather than being absorbed. In other words the car jumps rather than the tire moving up and over the bump while remaining in contact. Increasing suspension travel by decreasing spring stiffness allows the tire to flow over the bumps in the road by traveling with them. This is the reason for the need for balance between stiffness and suspension travel. Now the compromise is easier with progressive springs. They have two different spring rates in the same spring. The stiff portion deals with most suspension conditions with a stiff response but hard bumps move through the stiff portion and into the softer portion so the tire stays in contact with the road more. Better than hard springs but stiffer than soft springs. Also in here is the reason cutting your springs is bad. The force provided by a spring increases the more it’s compressed F=-k(X2-X1) where x is the position and k is the spring constant. As the change in x grows so do the force applied by the spring. Cutting a spring effectively reduces the amount of force it can apply.
Comments
and hard springs result in better handling. Thanks for the explaining the ‘why’ so well!
I’ve said for a long time that soft suspensions do exactly what this guy says when it comes to uneven roads. On a track, when the pavement is perfect, then it’d be fine to have a harder suspension, but anywhere else, you’re better off with a softer one.
Just got some reinforcement for what I have said for years! Yay!
Ok this KONI FSD system seems to make sense after this video together with some stiffer swaybar setup. Thanks!
I was always a fan of undersprung, overdampened setups. It’s usually in high end German luxury cars because you get a smooth ride with minimal bounce.
what about progressive springs?
So can this relate to a computer controlled air suspension system?
Ok first, the point of a suspension is to keep the tire in contact with the road. To this pursuit you must balance suspension travel with suspension stiffness. The reason for this need to balance is that as the cars weight shifts the suspension geometry, balance, and tire load. Essentially when you take a turn the force applied to the car isn’t actually acting on the center of mass. It’s acting below and to the side of the center of mass. As such what is actually happening is that the frictional force between the tire and the road is generating a torque on the car. This torque attempts to rotate the car around the center of mass. This lifts the inside tires off the ground and drives the outside front tire into the ground. The springs push the tires into the ground and counter act some of the rotation by applying their own torque to the center of mass. Now the stiffer the springs are the more they press the lifted tires into the ground and counteract the rotation of the center of mass. As such there is more weight on the other three wheels and thus they have more mechanical grip (IE friction), but this isn’t all, the suspension works best when everything is at a certain angle. The stiffer spring rate keeps this from changing as drastically. This also means that the whole car is easier to upset as drastic changes in road surface actually are translated to the whole chassis causing it to move rather than being absorbed. In other words the car jumps rather than the tire moving up and over the bump while remaining in contact. Increasing suspension travel by decreasing spring stiffness allows the tire to flow over the bumps in the road by traveling with them. This is the reason for the need for balance between stiffness and suspension travel. Now the compromise is easier with progressive springs. They have two different spring rates in the same spring. The stiff portion deals with most suspension conditions with a stiff response but hard bumps move through the stiff portion and into the softer portion so the tire stays in contact with the road more. Better than hard springs but stiffer than soft springs. Also in here is the reason cutting your springs is bad. The force provided by a spring increases the more it’s compressed F=-k(X2-X1) where x is the position and k is the spring constant. As the change in x grows so do the force applied by the spring. Cutting a spring effectively reduces the amount of force it can apply.