Progressively wound springs

来源:    日期:2014-10-8    浏览次数395

 These are the things to go for when you upgrade your springs. In actual fact, it’s difficult, not to get progressive springs when you upgrade - most of the aftermarke, t manufacturers make them like this, . Most factory-fit car springs are normally wound. That is to say that their coil pitch stays the same all the way up the spring. If you get progressively wound springs, the coil pitch gets tighter the closer to the top of the spring you get. This has the effect of giving the spring increasing resistance, the more it is compressed.

The spring constant (stiffness) of a coil spring equals:
k = compression / force = D^4 * G / (64*N*R^3)
where D is the wire diameter, G an elastic material property, N the number of coils in the spring, and R the radius of the spring.
So increasing the number of coils decreases the stiffness of the spring. Thus, a progressive spring is progressive because the two parts are compressed equally until the tightly wound part locks up, effectively shortening the spring and reducing its compliance.
So for normal driving, you’ll be using mostly the upper 3 or 4 ’tight’ winds to soak up the average bumps and potholes. When you get into harder driving, like cornering at speed for example, because the springs are being compressed more, they resist more. The effect is to reduce the suspension travel at the top end resulting in less body roll, and better road-holding. Invariably, the fact that the springs are progressively wound is what accounts for the lowering factor. The springs aren’t made shorter - they’re just wound differently. Of course the material that aftermarket springs are made of is usually a higher grade than factory spec simply because it’s going to be expected to handle more loads.
Note:Make sure you get powder-coated springs! This means they’ve been treated with a good anti-corrosion system and then covered in powdered paint. The whole lot is then baked to make the paint seal and stick and bring out it’s polyurethane elastic properties. It’s the best type. If you just get normally painted springs, the paint will start to flake on the first bump, and surface rust will appear within days of the first sign of dampness. Not good. Besides - powder coated springs look cool too!