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its pretty long... but for those springs/coilover newbies...this is some good information! let me know what you guys think

from Pure_adrenaline - OEM springs and struts are designed to work together. This means that the load rate on the springs are matched with the damping rate of the struts. Without struts, the car will bounce on the springs. Without springs, the car will drop to the ground. Therefore, the strut and the spring have to work in unison to soak up road irregularities while providing comfort and good handling.

Of course, there is an infinite number of ways to tune the strut and spring. It all depends on the vehicle's purpose.

Now what happens when you introduce an aftermarket spring to an OEM strut? Most likely, the load rate and the height are now different. This will make the spring and the strut out of sync from each other. However, in most cases and based on my personal experience, the ride does not suffer too much from the stiffer and lower springs because the OEM struts are able to handle the wider range of specs. That is assuming that the struts are in good working condition. But it is almost a certainty that you will shorten the life of the OEM struts.

You also need to consider the different designs of springs. For instance, there are springs that have a single rate throughout the length of the spring. Then there are springs like H&R that have progressive rates. Wider and softer usually, then as compression is applied to the springs, the narrower and harder coils kick in and provide a stiffer feel. You can see the progressive rates at a glance because the gaps between the coils are different top to bottom.

Contrary to popular beliefs, springs do not need time to "settle". Almost immediately after installation, as soon as the weight of the car is fully on the suspension, that's pretty much it. Also, springs from reputable companies explain the amount of the drop so it should be no surprise to anyone.

One thing to keep in mind is that, depending on the drop by the springs, you will inevitably shorten the travel height. This means you will be more prone to bottoming out the struts.

Now let's pair up an aftermarket spring with an aftermarket strut. Let's take Koni adjustables and Eibach springs, since they were mentioned in this thread. This is really not much better than, and certainly not the answer to, the OEM strut + aftermarket spring combination. Why? Because I doubt Koni and Eibach got together to match their engineering specifications. The Koni struts are simply designed to handle a more extreme range of specifications because most buyers buy them because they want stiffer ride with most likely a lower ride height.

So in essence, it is better than the OEM strut + aftermarket spring combination, but not THE answer. Oh, and, it is just fine to use these two combinations on the track. I have seen plenty of people using spring + strut combination at the tracks... even all-OEM suspension.




There is, of course, a better answer to the question than the aforementioned two options. It is the coilovers. Coilovers are an integrated unit consisting of a strut and a spring that are typically accompanied by other nice features such as camber plates, ride height adjustability, damping rate adjustability, etc. They also look nicer than OEM.

They naturally cost more because of the added engineering, materials and features that are involved. But often times, if you need these features, it's well worth the money. The strut and the spring are designed to work together at a lower ride height with adjustable preload and damping.




Now having ridden on adjustable coilovers for years, I can tell you that you really won't be changing the height setting much after the initial installation. Why? Because you have to get an alignment. It's a pain in the butt and costs time and money. Plus if the locking mechanism fails or rusts, you are looking at some bloody knuckles or costly repairs.

If you just want the dropped look with a slightly sharper ride, then I think springs on OEM struts will do just fine, especially if you are on a budget.

If you are on baller status and want the bragging rights, then by all means, the coilovers are your best bet because along with those two things, you also get the extra engineering. Or maybe you just don't settle for anything but the best for your car.