Which coil springs are the softest for a lifted TJ?
- Thread starter BigDan
- Start date
4,32 up travel, 5.09 down travel
or
nearly 4,7 up travel and 4,7 down travel with a 10mm spacer.
BUT when fully extended they would be too long so they spring would unseat
At the end of the day, you do the best you can. When stuck between an uneven ratio, my thought is to favor more up travel. Then move on.
As I mentioned in the other thread if the fronts unseat a touch I would not fuss over it.
It’s good form to verify the details before providing information that may not apply to someone else. (Sure, the difference might be practically undetectable, but even that’s an assumption until you verify the specs).
Normal shocks behave the same throughout their stroke, so positioning doesn't matter until you hit the limits. Bypass shocks behave differently.
Longer shocks dissipate heat better. Ideally you should run the biggest shock that fits and use bumpstops and limit straps to limit travel, not the shocks.
There's nothing magical about having ride height centered in suspension travel. When going fast having enough uptravel is more important so limited-travel rigs bias that way. For crawling more uptravel = higher COG so there can be benefits to minimal uptravel.
Longer shocks dissipate heat better. Ideally you should run the biggest shock that fits and use bumpstops and limit straps to limit travel, not the shocks.
There's nothing magical about having ride height centered in suspension travel. When going fast having enough uptravel is more important so limited-travel rigs bias that way. For crawling more uptravel = higher COG so there can be benefits to minimal uptravel.
Sorry If I dont understand it correctly, but english is not my native language.
Are you saying that the spring rate of those shocks wasn't 140lbs 3 years ago?
I’m no authority, but if I were in your postion, I’d probably run the spacer if doing so allows your bump stops to limit your up travel rather than bottoming out the shock. (And not worry about the spring barely drooping from the frame mount if it only happens under slower/crawling conditions).
No I was making a point that such details should not be overlooked/assumed. Most likely it’s moot, but that’s not always the case.
If you had double the free length and half the spring-rate, wouldn't that give you the same ride height and a "softer" ride? I'm sure this spring doesn't actually exist for our jeeps, but thinking theoretically here.
My understanding is that the 1000 pounds of weight you place on the, lets say for the sake of easy math, 100 lb rate springs compresses the spring 10 inches. If you place 1000 pounds on a 200 lb rate spring, the spring only compresses 5 inches. My understanding is that these two springs with different spring-rates could have the same ride height if their free lengths were appropriate (big distinction here).
Would the longer, lower spring-rate spring not compress more easily while going over small events than the heavier rate spring? Or would coil bind caused by such a long spring make this whole setup a non-start?
My understanding is that the 1000 pounds of weight you place on the, lets say for the sake of easy math, 100 lb rate springs compresses the spring 10 inches. If you place 1000 pounds on a 200 lb rate spring, the spring only compresses 5 inches. My understanding is that these two springs with different spring-rates could have the same ride height if their free lengths were appropriate (big distinction here).
Would the longer, lower spring-rate spring not compress more easily while going over small events than the heavier rate spring? Or would coil bind caused by such a long spring make this whole setup a non-start?
The key word is theoretically.
The problem is that, as you said, there are not springs with that big of a difference in spring rate for our TJs. You can check all the free lengths and spring rates at the sticky thread.
While the understanding is valuable, what does it matter? Short of custom, you can't buy that spring for a TJ.
That's where these discussions go sideways in a hurry. Everyone wants to do theory, they want to bring in 2-3" overall travel track cars with light corners weights, etc., blah blah blah. The problem is we are in the domain of a vehicle that has a relatively narrow range of spring options and a relatively narrow range of corner weights with a few outliers that don't count. In that domain, it is not possible to discern any difference in ride quality between any of the available springs that do their job. That job is defined as holding the rig up at the desired ride height and having enough free length to support reasonable shock travels. Once you make a spring do that job, they don't vary enough to tell.
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
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.