Pre-load or a higher rate spring? What's the difference? And dampening?

To start, I know a LITTLE about suspension but not a lot. The physics are simple but I need a bit of an explanation.

My situation is this: I have an Icon Stage 4 kit coupled with a Dakar leaf pack and it's been good to me. However, I'm wanting a bit of a softer ride since the truck spends 99% (or more) of its life on the road. And no, I don't feel bad about that. If you aren't driving 3 miles off road for every tank of gas you put through your Tacoma; you're in the same boat. But when I DO go offroad, I wheel some fairly gnarly stuff. I use every bit of my (down) travel and the truck performs great.

So I'm looking to potentially rebuild this set with CDC compression adjuster valves or I'm going to get a set of Kings with the adjusters on them. I understand this will give me the ability to firm up or soften the DAMPENING at a given time which sounds PERFECT for my use. Keep it soft when driving on the road and then firm it up a bit when I go do stupid stuff on the trails. Pretty sure I'm set on how this works. If I'm mistaken, please correct me.

What I don't understand is the resulting difference between increasing pre-load vs having a higher spring rate. Aren't they essentially achieving the same thing? I currently have a fair amount of pre-load on the front coils to achieve the desired amount of lift on my truck. It's within Icon spec though because I checked with them on the topic. My truck doesn't have a ton of armor on it so it's not super heavy.

Any advice offered would be greatly appreciated.

 

I was able to find this link that I believe answers my question. https://www.sportrider.com/technicalities-spring-rate-and-preload#page-5

As you can see from the picture below. The flatter line that starts higher is a softer spring rate with more preload. This would achieve the same lift height but would result in softer overall ride characteristics. The higher spring rate coil would be much rougher and is best suited for heavier vehicles.


So my conclusion is softer dampening and a slightly softer spring is more than likely where I need to be.

 

Yea but the top line is longer , the other is more horizontal . So how long a spring with different rate .......

 

Dampening: you're making it wetter, but only slightly.
Damping: shock action

 

If you have added preload on a 650# spring it still requires 650# of force to compress the spring one inch. A 700# spring without preload will require 700# of force to compress one inch. Adding or removing preload doesn't change the spring rate or what forces are required to compress it.
If you add preload on a spring it does make it feel firmer because there's already force on it and in turn requires a greater amount of force to compress it.
Your best move would be to opt for a 14" spring with the same spring rate to reduce the amount of preload while maintaining the same spring rate.

 

Is that available? I agree that would be the best of both worlds. Is that a common thing? What length are springs normally?

 

It would still take the same amount of preload if he keeps the same spring rate. Preload is not the number of threads showing. You measure preload by subtracting the free length and compressed length. I think the question is, would more preload and lower spring rate be harsher than less preload but higher spring rate. @*TRD* any thoughts?

 

Fox and Icon use 13” springs, Fox is 600lb and icon is 650lb. You can get 14” 600, 650 or 700lbs.

 

This is correct, lots of people mix these things up.

More preload is softer, unless you're bottoming out.

I prefer softer springs and lots of preload on a Tacoma. Then we prevent bottoming out with proper damping. The result is a much better ride.

 

Talk with Accutune! Ryan and the crew know a thing or two about Springs/Suspension and around get knowledge off their website as well!