Springs 101 – Linear vs. Progressive Springs

For our next installment of Springs 101, we’d like to discuss the two main springs used by Raceland (and most other coilover companies) with our coilover kits. While there are benefits to both types of springs used, they both can be used effectively when the kit and other components are designed around the type of spring. Let’s get into it…

Linear

The linear spring is probably what first comes to mind when you think of coilovers. Often, most coilover companies show images on their website and in their advertisements with linear springs for two obvious reasons: it is the most commonly type of spring used and they picture well. The linear spring is most times uniform in shape and has equal distance between each spring coil:

In function, the linear spring is a great choice for its reliability, consistency, and predictability. The linear spring will be the choice for performance drivers and racers for its predictable nature. The linear spring will retain the same spring rate regardless of how much it is compressed. Let’s say a linear spring has a spring rate of 250 lbs per inch. With what we know on the previous blog post of how to measure springs, they are measured by the amount of force applied to compress them by a unit of measure; in this instance an inch. That spring with 250 lbs per inch spring rate will take 250 lbs of pressure/force to compress it the first measured inch and then every following inch it will also take 250 lbs of pressure/force.

This is ideal for those interested in setting up an all-out performance vehicle or a race car. This non-variable spring rate will allow the driver to better predict the car through the suspension and have positive feedback through a high-speed turn on a race track. When set up correctly with the other components, a linear spring can still be a very comfortable and useful spring for the street as well.

Now you may be thinking, “this is the one for me!” Don’t rush to that conclusion, read further…

Progressive

The progressive spring can differ quite a bit from a linear spring in both shape and function. Often times a progressive spring will not have a uniform shape and can often times have ‘helper’ sections built into the spring so their coils may not be equidistant apart from each other:

In function, the progressive spring is often unmatched in its ability to provide equal measures of performance and comfort. Most vehicle manufacturers are going to use a progressive spring for their new vehicles for this balance. A progressive spring will effectively get stiffer and increase in rate the further it is compressed. This is why you often see aftermarket suspension manufacturers list a spring a ‘progressive’ instead of listing it by a specific numerical number like you would with a linear spring (it often doesn’t accurately describe the spring by giving it one numerical number). If a progressive spring has a 250 lbs per inch rate at the first measured inch, it could very well have a 350 lbs per inch second inch, 500 lbs per inch third inch, and maybe a 675 lbs per inch four inch.

As mentioned, this style of spring is ideal for street vehicles where it is important to have good balance between comfort as well as performance. A progressive spring is going to be able to handle road conditions often much better than a linear spring could. This doesn’t mean that you can’t get performance out of a progressive spring. In some cases, due to its nature, a progressive spring can often provide a higher spring rate during hard corners to keep the car flatter and very stable.

Well, which is better?

There are several factors that go into what style of spring is chosen for a specific vehicle. It’s not always as easy as determining that all Porsche owners are after all-out performance while all Cadillac owners want a plush ride. Aside from some Porsche owners wanting ride comfort as well and some Cadillac owners want to be able to increase handling performance, the chassis of the vehicle is a big determining factor of what is the best spring to use. Simply put, some chassis’ are not designed for and do not respond well to one or the other style when introducing a coilover kit. As mentioned, most vehicle manufacturers are going to incorporate progressive springs in their original design of the vehicle. Sometimes when you throw a linear spring into the mix it can disrupt the balance of the vehicle and create something that is neither comfortable nor will perform well. When that is the case, it is often best to design around the original intended spring to create that balance.

So, is there one style spring that is better than the other? No. Is there one that is better suited for a specific vehicle and chassis? Definitely. While we can’t speak for all coilover manufacturers, Raceland designs each coilover kit around what type of spring is best suited for that vehicle and chassis to provide the best balance between street performance and daily comfort.

Have questions? Feel free to give us a shout, 801-365-1440, or drop us an email at [email protected]

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