Which coil springs are the softest for a lifted TJ?

freedom_in_4low said:
They wouldn't give you the same ride height. The spring with the double free length and half the rate is always going to be twice the length of the other, at a given load.

Take a 24" 100 pound spring and a 12" 200 pound spring, and put 1000 pounds on each of them. The 100lb/in spring compresses 10" and the 200lb/in spring compresses 5". The 100lb/in spring is 14" installed and the 200lb/in spring is 7" installed. This 1:2 length relationship holds regardless of load.


To continue with your example you'd want the 200lb spring to be about 80% the free length of the 100lb spring to produce the same ride height with a 1000 pound load. But if that load changes, it falls apart. Less load and the softer spring will be taller, more load and the stiffer spring will be taller.


yes, the 24" spring will have less uptravel due to coil bind, and the 19" spring will have less downtravel because the spring will fall out of the buckets. Push the rates far enough apart and you have two springs that wouldn't be usable on the same vehicle because the travel ranges wouldn't overlap enough. And because of having to stay within rates that provide a travel range useful for the vehicle it's being applied to, the influence of spring rate, within the usable range of rates, over small, or any suspension events is so miniscule when compared to the influence of the shock that the springs contribution is imperceptible to the driver.
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So... in a complete vaccuum, far and removed from vehicle suspension, my logic still makes sense to me on a fundamental level. But it sounds like when actually applied in practice, moving the values (spring-rate and free length) too far in either direction breaks my abstract reasoning. Thanks for the lesson
 
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TJim said:
That's not the same thing.

Spring rate remains the same with either full or empty gas tank.
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It actually isn't that far removed since a rig will respond very differently between the rear load it normally carries (assuming that rides well) and then when you empty it out. I won't even hand a set of shocks to the tuner unless the owner promises to keep the rig at around the laden weight I have them tuned for.
 
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YonderNorthwest said:
Understood. Was just curious if my understanding of the underlying physics was flawed. It is not, but for our purposes it doesn't matter. Thanks
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It is and it isn't. All this goes away if you or anyone else who wants to know will go unbolt the rear shocks off of the rig and go for a test drive safely. What you learn for that scant few minutes of effort is priceless.
 
Based on that and past tangled arguments about the cause of stiff rides I'm changing my usual reply to those complaining their springs are too stiff. Rather than work to convince them it's their shocks causing the stiff ride I'll instead say remove your shocks and see if you still believe afterwards that your springs are the cause of the stiff ride. And post a photo showing the removed shocks. 😏
 
Jerry Bransford said:
Based on that and past tangled arguments about the cause of stiff rides I'm changing my usual reply to those complaining their springs are too stiff. Rather than work to convince them it's their shocks causing the stiff ride I'll instead say remove your shocks and see if you still believe afterwards that your springs are the cause of the stiff ride.
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I have never understood why so many refuse to do something so simple that could easily prove everyone wrong if they are so stoutly entrenched in their position that it isn't the shocks. Alright, if it is the springs causing the harsh ride, pulling the rear shocks makes you a fucking hero, go do it. But nope, rather argue theory and bullshit.
 
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Shocks and springs work together. They were modeled with inductors and capacitors when vehicles were designed. Suggesting that removing the shock will tell you anything is bullshit. That's not how it works, it never will be. Saying that there are few springs that fit in a TJ and do the job at a particular height is valid. Pulling the shocks is 100% bullshit and should stop. It won't tell you anything.
 
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pagrey said:
Shocks and springs work together. They were modeled with inductors and capacitors when vehicles were designed. Suggesting that removing the shock will tell you anything is bullshit. That's not how it works, it never will be. Saying that there are few springs that fit in a TJ and do the job at a particular height is valid. Pulling the shocks is 100% bullshit and should stop. It won't tell you anything.
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You should go for a drive without shocks and tell us how floaty, bouncy and uncontrolled your jeep has become without them. Then try to mitigate the floaty, bouncy, uncontrolled ride with the commonly available TJ springs.
 
jjvw said:
You should go for a drive without shocks and tell us how floaty, bouncy and uncontrolled your jeep has become without them.
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Why? like I said they work together. Obviously it would drive like crap without shocks. A model T has dampers, only an idiot would think a vehicle would drive okay without them.
 
pagrey said:
Why? like I said they work together. Obviously it would drive like crap without shocks. A model T has dampers, only an idiot would think a vehicle would drive okay without them.
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No one made that claim and that isn't the point.
 
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The guy in this thread changed his springs and drove around the block. The ride was worse. He didn't bottom out the shocks or reach the limits of travel. The ride was just worse. Asked for a spring, probably isn't available like the Easter Bunny has said. No big deal. The springs he wants aren't available, that's really it. People can flap their jaw all they want, that's it.
 
I understand the Easter Bunny trying to focus on shocks, that's right in every way. The problem is it doesn't mean people like me and Dan don't have changes in ride quality due to springs. His question is so simple in essence, it doesn't need all this. I have three different springs, CC782, CC780 and stock. They all ride different. When people say they don't what do you expect me to do, lie? I can swap them while you wait.
 
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