Stock vs aftermarket!
 

I thought stock springs will last forever and aftermarket springs will need to be replaced after every 30k miles or so.

I've never heard of this. Ever.

:iagree: The stock shocks might go after 30k miles, but the springs usually do not ever have any issues ...unless you live in an area that experiences ridiculous corrosion issues.

Well I only know because of what i've heard from people who have graduated from automotive schools and who have automotive careers. They said stock springs will always last longer and aftermarket springs have to be replaced cuz the shocks.

The shocks would have to be replaced, not the springs.

Are shocks expensive?

You could probably find a reasonably priced set of takeoffs from someone who went with coilovers. Depending on how low the springs you get are, you might not even have a problem.

I'm under the impression that OP does not know the difference between shocks, springs, and suspension.

Suspension is the sum of the parts that isolate (or transfer) the energy of the road from/to the driver. The shocks and the springs are the two major components that make up this system.

I think what your friends, who graduated from automotive schools, are referring to is the fact that using lowering springs with the stock shocks will put more stress on the shocks and, therefore, wear them out sooner than the stock springs. This all depends on your level of drop ofcourse and what kind of roads you drive on, ymmv. The reason they wear out sooner is because, with lowering springs, they are no longer operating within their specified range of motion.

Stock shocks should be pretty cheap to find used. Otherwise, it's not a bad excuse to upgrade to Koni Yellows.

To add to this, I think drastic difference in spring rate can cause early blowout too.

Look at how the NF210 spring rate is vs oem
http://www.the370z.com/brakes-suspen...ing-rates.html

So I am right cv129?

I wish I knew how spring rates affected suspension and handling characteristics. Unfortunately it's beyond my basic operating knowledge of the subject. One more thing for me to read up on. :tup:

Umm I'll let some more senior/experienced members to articulate the answer technically. In short, like other members have stated, its the shocks/dampers that potentially needs early replacement, not the spring.

If or when that happens depends on how much shorter AND the stiffness of chosen springs, like dp3ngu1n said

This. Unless the spring actually breaks, it will not need replacement at any point. It's a spring. There's not a whole lot that can happen to it. The shocks may wear out early. They may not. It really depends on how low you go. A little bit of drop (Swift, Eibach, etc) does not seem to be causing too many blown shocks, or we'd see a whole lot more WTB:Shocks threads in the marketplace. If you slam the car, it's likely you'll eventually damage the shocks. It may be in 30k miles, or 3k miles. If you want to disregard correct suspension geometry and slam the car to the ground, just buy coilovers and skip aftermarket springs.

Thanks for the input Chuck!