Originally posted by giago
What is the difference whith the linear rate springs & progressive type ??
Well here is the difference. A
linear spring as the same spring rate from top to bottom. The coil is evenly spaced throughout its length. Its inner/outer diameter is also the same throughout. The advantage of this spring is best felt in Motorsport application. Because it is
linear when a car enters a curve and starts transferring weight and compressing the coils in the suspension, it will do so at a
constant or in a linear way until it is fully compressed. The disadvantage to these springs in a street set up is, they are usually stiffer, less forgiving for the ride comfort.
In this picture, you can see my linear spring made by Eibach and used in the rear of my European and modified PSS 9. FYI, on this spring you can see the manufacturers name, Eibach, the date it was made, 7 months of 2002, the type of spring, ERS which stands for Eibach-Race-Spring, its free length at 200 mm, its inner diameter (ID) at 70 mm, and its rating, here in Newton/mm at 110 which translate into approximately 627 lbs/inch. This means to compress this spring one (1) inch, the car must exert 627 lbs of force.
On the other hand, a
progressive spring is just that,
progressive and
not constant. It is usually a lot wider at its mid point in the coil with both ends having smaller diameters. Also the space between the coils will be usually different, meaning they will not be constant. This as for effect a softer more cushiony ride level. Good for the street bad for the track. the way it works is that as a car enters the curve it starts to compress the softer part of the coil. As you push further it enters the more linear of stiffer part of the coil. Like I said it is smoother for road use but not as precise for track use. This can be explained the following way. Since Motorsport usually means fast transitions from one curve to another a car with progressive springs will make those transitions harder and more vague for the driver by first compressing rapidly through the progressive part and then abruptly hitting the linear part. This can have as a consequence the car being jerked around by the coils. I don't know if this makes sense to you but it is as best as I can explain it to you.
In this picture you have a progressive spring. Sorry for the quality of the picture.
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