Hi, I’d like to open a discussion of progressive spring design. It is not intuitive, but unequal spacing between coils and thickness of wire is NOT what makes a spring progressive! Here is the explanation of what makes a spring behave progressively:

Take a 100 lb/in linear, 10 coil spring and put 100 lb of force on it. The spring is going to compress by 1 inch and each coil is going to compress by 1/10 of an inch. Now put 200 lb of force on the spring. The spring will compress by 2 inches and each coil will compress by 1/5 inch. So in fact, each coil in that spring has 1,000 lb/in rate.

Now take the same wire and make a progressive spring by doubling the number of coils in the upper half portion of the spring. If you put a 100 lb of force on this spring, each coil is still going to compress by 1/10 inch (because it is made of the same wire), but since you doubled the number of coils in the upper half portion, the net compression of the spring is going to be greater than 1’’ because there are more coils contributing to the net result. If you put 200 lb of force on this spring, each coil is going to compress by 1/5 and so on. Note that each coil in the progressive spring also has 1,000 lb/in rate and spring will behave identical to a linear spring with a 75 lb/in rate constant!!

You can vary the thickness of the wire in each coil, you can vary the diameter of each coil, you can vary the space between coils, but the spring will behave linearly no matter what your design is! So why is the term “progressive” used? Actually when you double the number of coils in the upper portion of the spring (the design of Hperco and Road Magnets) you effectively reduce the distance that each coil can compress. For example, as soon as 5 coils in the top portion begin to collide, you have left with another 5 “working” coils, and since each coil has (for example 1,000 ln/in rate), your net spring rate instantaneously goes up to 1000 (lb/in) / 5(remaining coils) = 200 lb/in. So, for a spring to behave progressively you have to have this binding effect going on ALL the time, otherwise it will behave linearly! In order to progressive design of the spring you have to deal with coil binding every time you go over a bump, witch will eventually throw off spring constant due to stress associated with each collision.

Aftermarket spring manufacturers for our cars, such as Hyperco, Road Magnets, Intrax etc. design their progressive springs in such way that when the car is at rest the coils in the top half portion of the spring are already laying on the top of each other. So when you drive your car, you experience linear behavior of the spring + noise. The purpose of those upper coils is to hold the spring in place when you jack up your car or jump over something. That is why progressive design is not very popular among car manufacturers. Progressive springs became popular in off-road racing applications where spring life and binding noise is not important.

IIRC roadmagnets is not progressive.

^^ ouch! owned.

dead coils designed into a spring are different then having an actual progressive rate spring. RM was designed with dead coils to ensure that the spring stays in contact with the upper and lower perch at full bound

dead coils designed into a spring are different then having an actual progressive rate spring. RM was designed with dead coils to ensure that the spring stays in contact with the upper and lower perch at full bound

Hi, the whole point of my post was that there is no such thing as "progressive rate." Any spring of any design will behave like a linear spring if coils don't bind. The "progressive" effect comes into play when coils collide as spring compresses!

yes there is such a thing. The term is used to describe a spring that utilizes a coil design that when compressed, some coils touch, effectively changing the spring rate. dead coils are touching from the start.

dont arge with rob dude he gets us the group buys on many a suspension parts.... most of which im just over the budget to jump on, but i will and i've talked to him on the phone w/ some ?'s and he's got answers. my .02

I don't have my machine design texts here, but your logic is all wrong. Spring design involves the entire spring length, from end to end. If you look at one coil at a time, you have to consider each coil as one spring and the assembly then becomes that many springs in series. When springs are in series, their deflections are not the same. So, the deflection of each coil can be different. Check any text on machine design elements. The formulas are pretty simple. Any spring with unequal spacing in the coils will have a non-linear (progressive) spring rate.

Progressive springs mostly suck so who cares. I have no experiance with RM. We don't need or want Progressive springs with our cars. It's simply a fact that we don't have enough suspension travel to take advantage of them. We need stiff springs from the start and as a rule people who design progressives always try to go soft at the start and then make up for the softer rate by going stiff at the end. If someone would design a spring like the hyperco that was at least 300 from the start and then got stiffer at the very end that might have some merit. Other then that, it's a waste. Even then it's probably not worth the trouble as you can just use a long Koni bumpstop and get a similiar effect.

Hi, I’d like to open a discussion of progressive spring design. It is not intuitive, but unequal spacing between coils and thickness of wire is NOT what makes a spring progressive! Here is the explanation of what makes a spring behave progressively:

Take a 100 lb/in linear, 10 coil spring and put 100 lb of force on it. The spring is going to compress by 1 inch and each coil is going to compress by 1/10 of an inch. Now put 200 lb of force on the spring. The spring will compress by 2 inches and each coil will compress by 1/5 inch. So in fact, each coil in that spring has 1,000 lb/in rate.

Now take the same wire and make a progressive spring by doubling the number of coils in the upper half portion of the spring. If you put a 100 lb of force on this spring, each coil is still going to compress by 1/10 inch (because it is made of the same wire), but since you doubled the number of coils in the upper half portion, the net compression of the spring is going to be greater than 1’’ because there are more coils contributing to the net result. If you put 200 lb of force on this spring, each coil is going to compress by 1/5 and so on. Note that each coil in the progressive spring also has 1,000 lb/in rate and spring will behave identical to a linear spring with a 75 lb/in rate constant!!

You can vary the thickness of the wire in each coil, you can vary the diameter of each coil, you can vary the space between coils, but the spring will behave linearly no matter what your design is! So why is the term “progressive” used? Actually when you double the number of coils in the upper portion of the spring (the design of Hperco and Road Magnets) you effectively reduce the distance that each coil can compress. For example, as soon as 5 coils in the top portion begin to collide, you have left with another 5 “working” coils, and since each coil has (for example 1,000 ln/in rate), your net spring rate instantaneously goes up to 1000 (lb/in) / 5(remaining coils) = 200 lb/in. So, for a spring to behave progressively you have to have this binding effect going on ALL the time, otherwise it will behave linearly! In order to progressive design of the spring you have to deal with coil binding every time you go over a bump, witch will eventually throw off spring constant due to stress associated with each collision.

Aftermarket spring manufacturers for our cars, such as Hyperco, Road Magnets, Intrax etc. design their progressive springs in such way that when the car is at rest the coils in the top half portion of the spring are already laying on the top of each other. So when you drive your car, you experience linear behavior of the spring + noise. The purpose of those upper coils is to hold the spring in place when you jack up your car or jump over something. That is why progressive design is not very popular among car manufacturers. Progressive springs became popular in off-road racing applications where spring life and binding noise is not important.


1) You eliminate noise by having the coils that touch wrapped in rubber or some other material.

2) Coil bind is ussually a term used for when all the coils in a spring bind causing the spring to go solid. Your term works but I don't want people to confuse it in the context of the GC springs we use normally.

3) Only progressive spring to use is one with a shortened Koni in the oem housings. In that situation they are a good riding setup with a little more firmness. Eibach makes a set with a 1.4ish drop. Add a shorter koni and you are only loosing about .4 inchs. It's a decent option.

Totally agree with the first statement, but it's just my preference.

The original poster doesn't have a clue, and hasn't visited the board since creating this thread. Check out some of his other wonderful threads when you're bored.

C

The original poster doesn't have a clue, and hasn't visited the board since creating this thread. Check out some of his other wonderful threads when you're bored.

C
I have checked out his other threads. And have flamed the living sh*t out of him on more than one occassion. Just for chuckles. :D