I've got the 3" JKS springs on mine. I like them just fine since they gave me the full 3" lift height as advertised and that's all I expect from springs.
Dual rate springs: JKS JSPEC dual rate versus Metalcloak dual rate
- Thread starter 01TJ-Blues
- Start date
they do this:
and they also do this:
and they made my Jeep look like this:
and I like all of those things.
and they also do this:
and they made my Jeep look like this:
and I like all of those things.
What shocks and shock dimensions are you using with the 3" lift?? There has been some discussion about problems finding shocks to fit a 3" lift to get max articulation.
Would like a dual rate springs for a softer ride but don't want too high a lift or I'll need a ladder to get in with a 1" body lift. Right now committed to true 32" tires and was almost set on 2933 front, 2942 rear OME 2.5" springs and 1" lift to give them room to move.
Would like a dual rate springs for a softer ride but don't want too high a lift or I'll need a ladder to get in with a 1" body lift. Right now committed to true 32" tires and was almost set on 2933 front, 2942 rear OME 2.5" springs and 1" lift to give them room to move.
Yep, shocks for 3" springs can be tricky. I run Rancho 5000x. The recommended fronts (239s) were just fine, but after the CV driveshaft and tummy tuck, the rears (originally RS55241s) were too short. I moved to 256s and I'm happy. I will say, without the body lift, the shocks would be a bit trickier to sort. My tires are 285/75r15 (~32.8"). FYI, that last picture is pre-body lift.
https://wranglertjforum.com/threads/prndls-tj-build-ii-the-green-one.55717/post-1070743
Compressed | Compressed | Extended | Travel | Up | Down | Bias |
|---|---|---|---|---|---|---|
| Rancho RS55239 (Front) | 14.43 | 23.84 | 9.41 | 5.25 | 4.16 | 56/44 |
| Rancho RS55256 (Rear) | 15.06 | 24.68 | 9.62 | 4.75 | 4.87 | 49/51 |
Springs create the ride height. Shocks determine the ride. Don't confuse the two.
I am running the JKS 3" with a 1" body lift. That setup fits 285/75R16 very well. For shocks I am running Bilstein 24-185264 and Bilstein 24-185257. I believe I am running approximately 2" of bumpstop in both front and rear. Which works well with both shocks and tire rub.
I have been extremely happy with my JKS dual rate springs. (For reference, I previuosly ran BDS springs with Bilstein shocks). The JKS springs are nice because, unlike more popular dual rate springs, the JKS ride in the softer part of the spring and you only get into the heavier part as you load up your Jeep. Because of this they handle loads better than linear rate springs. I think handling is improved as well. For example as you enter a corner and the body starts to roll, it hits the firm site of the spring on the outboard side while the inboard side is being pushed up with the softer rate. But that is only in theory. If feels like it handles better, but I have no way to confirm any handling advantages. It may be placebo effect. But I do like how the JKS coils carry a load without being too firm when empty. I think the Bilstien are also a good match. The bilstein shocks have a very linear rate on compression but they are digressive on rebound. That means that during the compression stroke the spring and shock are both working together to get firmer the deeper/faster you go into the travel. During the rebound stroke, the Bilstien are digressive, making them immediately slower rebounding to better control the stored energy in the fully compressed spring. Some people may find the Bilstiens a little harsh offroad and if you are doing high speed whoops the slower rebound could cause your shocks to pack up. But for they typical daily driver that sees mostly street or highway use, the Bilstiens work fantastic while also providng a very stable and controlled ride offroad.
I have been extremely happy with my JKS dual rate springs. (For reference, I previuosly ran BDS springs with Bilstein shocks). The JKS springs are nice because, unlike more popular dual rate springs, the JKS ride in the softer part of the spring and you only get into the heavier part as you load up your Jeep. Because of this they handle loads better than linear rate springs. I think handling is improved as well. For example as you enter a corner and the body starts to roll, it hits the firm site of the spring on the outboard side while the inboard side is being pushed up with the softer rate. But that is only in theory. If feels like it handles better, but I have no way to confirm any handling advantages. It may be placebo effect. But I do like how the JKS coils carry a load without being too firm when empty. I think the Bilstien are also a good match. The bilstein shocks have a very linear rate on compression but they are digressive on rebound. That means that during the compression stroke the spring and shock are both working together to get firmer the deeper/faster you go into the travel. During the rebound stroke, the Bilstien are digressive, making them immediately slower rebounding to better control the stored energy in the fully compressed spring. Some people may find the Bilstiens a little harsh offroad and if you are doing high speed whoops the slower rebound could cause your shocks to pack up. But for they typical daily driver that sees mostly street or highway use, the Bilstiens work fantastic while also providng a very stable and controlled ride offroad.
I’ve got jks 3 inch springs. No complaints worth noting. I got them because they cost less than Currie springs and jks is a Detroit manufacturer.
Great guys, thanks for all your “opinions”. I’ve run JKS components on my XJs years ago and was always impressed with the quality. Now that I’ve been allowed back into the Jeep community, I gravitated to a company I know. Very mildly mod’d daily driver is the theme here. I’ll post up when I get everything installed. Cheers 
I think shock tuners do care about spring rate. They might not be looking at the numbers. They might not even be thinking about spring rates, but the rate of the spring is going to affect how a vehicle behaves. A softer spring is going to handle a load differently than a stiffer spring. How the spring handles the load will need to be addressed by the shock and the shock tuner. Even if you don't care what the spring rate is on a spring, the shock needs to be tuned to handle the moving mass. Yes, its a weight issue, but the spring carries that moving weight. Given the same amount of weight to carry, a stiffer spring moves less than a softer spring. How could a shock tuner not take into consideration the amount of movement that a vehicle suspension is making. They are accounting for spring rates when they are accounting for the amount of mass that is moving.
I understand what you are saying. Spring rate isn't the place to fine tune ride decisions. Shocks will play a bigger role in how a vehicle rides and behaves. But coil choice is the place to start when looking at how to support your weight and what you are doing with the Jeep. Dual rate springs handle weight differently than single rate coils.
You pick any spring that gives you the ride height you need and I can make it ride like total poo and then do amazing things around corners, dial out small event harshness, and soak up the bigger stuff and never touch the goddam springs.
And yet one more fucking time. Once you set up coil overs and get the ride height dialed in with the correct amount of preload, all that other bullshit you spewed out goes out the fucking window.
Tuners care about the spring rate right up until the point they get the ride height they need with the correct preload and the basic rules of springs followed which is you don't split the main and secondary too far in rate, and the lengths are proper. After that, they simply don't give a shit.
Tidying up some packaging and thinking back on this, I clearly overlooked the obvious. I have likely singlehandedly paid for more shock tunes than any other single person you can dig up. Guess what the #1 question I have never been asked is, nary a single time? That's right, what is the spring rate? Not once.
All that theory is fine, but it goes out the window if you look at the available TJ springs that you can ACTUALLY buy for a given ride height. They are all close enough that terms like "stiffer" and "softer" become pretty much meaningless. In other words, get the absolutely STIFFEST TJ spring you can buy, put them in your jeep, take the shocks out and go for a short drive. Then tell us if spring rates matter as much as you think they do in our application.
I have LSC adjusters in my Fox shocks. With no other change to the vehicle whatsoever, I can adjust the LSC settings to make the jeep feel loose like you don't have the swaybars connected on the lowest setting, and make the jeep feel super stiff and unpleasant, feeling like a overinflated bicycle going on potholes on the highest settings. This observation will not change even if I went and changed the springs (irrespective of rate) to something else as long as I have the same ride height and same shock travel bias.
Last edited:
Oh yeah, I agree fully. I'm not saying that spring rates should be used to determine your ride. They are a small part of how a jeep will ride. Shocks by far play a bigger role in ride and handling. I also agree that a custom tuner can work with any spring rate to dial in what they are looking for.
I was just saying the dual rate springs work well for carrying a load. I did mention handling advantages, but I thought I was clear that could not be validated. Its mostly theory used by some spring manufacturers. Because this can not be confirmed or denied short of taking a Jeep to a skid pad, I should not have mentioned it.
I also should have been more specific when I talked about how the dual rate spring is better at carrying a load. I was referring to carrying loads that vary in weight from weekend to weekday. In that situation, I think a dual rate spring is a good alternative to using airbags. If your Jeep weight remains mostly constant, I don't think a dual rate spring has any advantage. Get the coil that carries your weight and get the best shocks you can afford.
To be clear, I agree with mrblaine that shocks can make or break how a Jeep rides and handles. The coils simply carry the weight. I even agree that Bilstien have some small event harshness. But I think that slight hashness will bother some people more than others. For my needs, which are mostly highway driving with occasional trips were I am carrying a heavy load, I prefer how the Bilstien handle. I also really like how the dual rate coils allow me to pile in more weight for a long trip. So I choose that compromise. If I was doing more offroad oriented rock crawling, I would likely prefer a different shock.
I think part of the issue when dealing with coils and shocks is that its easy for people get the mistaken idea that changing coils will transform the way their Jeep handles. It will not. Any changes made by the coils alone will be very subtle if at all. And some of that may be attributed to other factors as well. The shocks will have a greater effect on ride and handling. I think another part of shock/coil conversation that gets into a heated disucssion is when we start mixing in over the counter shocks with custom tuned. No question that a custom tuned shock can be tuned to perform precisely as intended without knowing the coil rate. But over the counter shocks cover a broad array of performance parameters. I don't think there is a one size fits all when it comes to choosing over the counter shocks. I was simply trying describe how the liner/digressive design of one shock may differ in performance from a more progressive design of another shock. My apologies if I misrepresented the role that spring rates play in tuning a shock or tuning a Jeeps handling.
i installed the jks 3" with ranchos. gave me 3" i like the look. have not driven yet. need to get gas tank back in. i have metal cloak on my other lj with ome shocks. will be able to give a side by side compare once the jks lj is buttoned back up.
You are still operating under the misguided assumption that the custom tuner knows or cares what the spring rate is. If they aren't asking me what it is, what does that mean?
I can confirm. I also have LSC adjusters on mine. The difference in handling between the highest and lowest setting is quite dramatic.
How confident are you that your springs are really dual rate and not just dual wound? There is a difference. And to the best of my knowledge, there are no commonly available dual rate aftermarket coils available for the TJ.
You can confirm yours with a caliper by measuring the wire thickness across the length of the spring.