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I am at 120k miles on a 2015 and still on OEM struts. Cannot get the whole suspension kit for the front end like the 2014's which are available via KYB. Ideally would like to replace the complete suspension but it kind of gets expensive...

So my big question is for any metallurgy experts in this group,

Does the suspension spring metal fatigues and gets softer over a period of time/cycles?

If I am touching the front suspension I want it to come as close as possible to a zero-mile state, but if older springs are going to make the front end softer/harder, then I would want to replace the springs and rubber components as well...

Anyone who has done this can please chime in......

Javvy
 

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Discussion Starter · #2 ·

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The only time you would need to replace the springs are when they are under constant stress such as driving with shot/broken struts or the vehicle is always loaded to its limits. In those cases you would want to go with new springs. In those cases most f the times you can notice the deformity in the springs. Otherwise for regular driving cycles where you are not navigating potholes frequently, repalacinng Struts is just fine. Some dedicated suspension shops aalso carry a machine which can test spring compression and bounce back under different loads. You can try that, if you have one in your area,.
 

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Springs regulate height. If they are failing you will notice the vehicle sagging in any corner. You v=can monitor spring health by measuring your van's height at each corner. Pick a way to measure it and stick to the same method each time. You can measure from center of the wheel to the fender lip or from the ground to the pinch welds. If the distance lessens then the springs are starting to fail.
 

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So my big question is for any metallurgy experts in this group,

Does the suspension spring metal fatigues and gets softer over a period of time/cycles?
Not an expert but took a high level class as part of my mechanical engineering degree. It depends how the spring is made. Metals can creep over time under load (slowly deform). This is not usually a big factor.

Second is fatigue failure. With sufficient stress during cycling, metals will fail over a large number of cycles. It depends on the stresses seen, and the failure can be hundreds of thousands of cycles or more. For some metals, like steel, they will never fatigue fail if the cycle stress is kept below a certain point. (Others, like aluminum, will always fatigue fail eventually)

I have no idea what stresses suspension springs see vs the strength of the springs. I doubt fatigue failure would come into play for any normal conditions though. I also don’t recall fatigue softening metals over time, but again it was a very high level course in material science.

All that said, I doubt it is a big factor here with the springs in a suspension. Unless something is obviously wrong, I wouldn’t worry about changing the springs.
 
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