can someone explain Linear and Progressive?

[THUNDERZ]

Not clear on the meaning. Thanks.

[blueovalz]

Assuming this relates to springs on a car.....linear means the spring rate is constant (e.g. 100 lbs/inch for each and every inch of compression, so that it would take 300 lbs to compress this spring 3") throughout its useable range. This type of spring has all the coils spaced the same distance from each other (for a constant size wire).

A progressive spring rate is one that increases it's rate as the spring is compressed (e.g. the first inch of compression may require only 50 lbs to accomplish, but the next inch of compression may require, say, 100 lbs to compress. This type of spring can be visually identified by the different lengths between coils along the length of the spring, with the first couple of coils (spacing) different from the rest of the coil spacing

[EvilRufusKay]

I'll take a stab at it. I assume you are talking spring rates?

 

 

Design Types: Normal, Step Linear and Progressive Springs

 

1. Normal Springs (Linear rate Springs, Specific Rate Springs)

 

In a normal spring, space between the coils are equal. Normal (or linear rate) springs are designed to respond with a specific rate when compressed.

 

Consider we have a 10-coil spring, each coil spaced 2 centimeters apart. Put a load on the spring to compress it 2 centimeters. Because in Normal Springs coils compress at the same rate, this 2 centimeters will be divided into all 10 coils equal, resulting each coil spaced 1,8 cm apart. Put another additional load which is the same as the first one and the coils will become 1,6 cm apart.

 

2. Step Linear Springs (2 Step Linear Springs)

 

These are springs that have a 2 different spring rate.

 

In a two-step linear spring, about half the coils have shorter spacing. As the spring compresses, the coils move closer. At a certain point, the shorter spaced coils touch, effectively eliminating them from the spring. You then have a spring comprised of only the longer coils. This "second-step" spring will be much stiffer than the whole spring (the more coils, the easier it is to compress the spring). The result is that you have one set of handling characteristics before the shorter coils touch and then you have another, completely different level of response after they touch. (HyperPro website)

 

3. Progressive Springs (Rising Rate Springs, Progressive Rate Springs, Progressive Wound Springs)

 

In progressive springs each coil is spaced differently and they have a variable spring rate. When free, it is easy to compress the spring for first centimeters. As you apply more forces, coils on a progressive spring come closer. After a certain point, coils at the top 1/4 of the spring begin to touch each other and finally become inactive or dead, and that makes the spring stiffer. Apply more forces to a progressive spring then it becomes stiffer because as the number of active coils in a spring decreases, the spring rate increases. So, a progressive spring may both be sensitive to very small bumps on the road, while giving the stiffness you need during hard braking and turning.

 

Rufus

[JMortensen]

OK, my $.02 now:

 

If you're driving a street car and you want a comfortable ride on small road imperfections, but you want to push the car a little harder than the average driver, progressives or dual rate springs will work.

 

For anyone even 1/2 way serious about handling, autox, road racing, track days, hard street driving, etc, progressives are a bad idea IMO. The reason being that the suspension has to blow thru the soft spring rate to get to the "real" rate, causing excessive body roll when turning and excessive nose dive when braking hard. Also, if you're in a nice steady state sweeper and you hit a bump, the car will probably bounce into the softer rate, then have to settle back into the real rate again. This situation of loading/unloading/loading the suspension is hard enough for the suspension to control when you have a good single rate spring, but progressives will make it worse. Someone posted a few months ago that Susp Tech was offering a setup for a ZX IIRC with progressive springs in front and linears in back. That is, AFAIC, the worst setup possible.

 

If you're the "princess and the pea" type, or you don't really care about handling that much, then consider the progressive springs. Otherwise just get a good linear spring.

 

Jon

[auxilary]

I dunno if I like progressive rate springs. I drove davyz's car with progressive rate eibachs, and on turns, there was a lot more body roll. The spring would compress more, and stabilize the car. It just felt odd

[THUNDERZ]

Thanks Guys!