Spacers vs Springs

[apb]

Thanks @Roky and @rustyshakelford , appreciate the input. Going to pull the trigger on one of the kits first of the year, or if Brett releases his BnL special I may go that route.

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[RV Wrench]

I'll chime in and tell you what I have and why I like it. I have tried a few different things, and this is what I settled on:

-1.5" spacer lift. I love the factory spring ride and even in bone-stock form, they work excellent on the trails. I settled on this lift because I wanted to keep the CG as low as possible and keep the suspension closest to its original design. I also dont want a rig that I need a ladder to climb into.

-adjustable lower front control arms. Perfect for adjusting out the wandering issue. I have RC arms, and they seem to be a great design.

-adjustable front track bar. Just to get the alignment back to spec with the lift, though it was only off by a fraction of an inch. I have the RC adjustable track bar.

-RC Vertex shocks. Best mod to the Jeep, barnone. They collapse the same as stock, but extend about 1.5" longer than stock, adding flex. The ride is great everywhere, just turn the clickers to your liking.

All this works excellent with 35" tires in the stock wheel wells with no bump stop modifications. I'll be going bigger, but I'll be opening up the wheel wells to fit, not lifting the Jeep more. The only real "issue" I have had with this setup is the belly hangs *just a tad* lower than the belly on my YJ. In my 2-door, this isn't a big issue for most the trails I wheel on.

And no, I have no affiliation with RC. I have used their products in the past, along with many of my buddies, and they are excellent about standing behind their products. A lot of the big name brands (FOX especially) have virtually zero customer/product support.

Alot of choice depends on what tire size you want to end up with, and if you are doing it to wheel or for appearance. My choices were entirely based on wheeling' capability while maintaining a great ride.

 

[word302]

Most of the lift kits I see recommended are effectively spacer lifts. You have a group of coils at the top of the spring that block up under the weight of the jeep, giving you height, with the rest of the spring being similar to the stock spring rate.

Only difference between that and an actual spacer lift is the top coils will decompress when the jeep is unloaded, allowing for a much taller spring than stock + spacer, which allows you to run much longer shocks without limiting straps.

The problem with that is, you're going to run into front driveshaft issues once your front shocks are longer than 28-29" extended.

Stock front springs with 2" spacers can easily accommodate 28" long shocks without limiting straps and without coming unseated.

So if you don't want to replace your driveshaft, you will not gain anything by going with springs instead of spacers. And arguably, spacers would be better, because you'll get exactly the amount of lift that's advertised.

As far as track bars, I would be careful not to overstate their importance.

I have some numbers written down from when I went over my stock jeep and measured everything, so this is not "fresh" information and please correct me if I'm wrong. But the stock front track bar is 34" long, and the frame-side mount is 2" higher than the axle-side mount. So what happens when you lift your jeep 2"? The difference in the length of the BC measurement (Lbc) in the following image is how much your axle will shift to the driver's side after a 2" lift. It shifts just under 2 tenths of an inch.

You can decide for yourself if correcting that is worth hundreds of dollars.

Then as far as lower control arms and caster correction. I see a lot of people throwing out brands with little rhyme or reason to their recommendations besides "it's what I have, and I like it".

In my experience, from what I've seen, from what I've worked on, from what I've owned, the best joints in the industry are currie johhny joints, and the best adjustment mechanism is a simple threaded shank with a jam nut. These are more difficult to work on because one end of the control arm needs to be removed from the jeep in order for adjustments to be made. And jam nuts are more difficult to tighten than pinch bolts. But the effort is worth it.

So you should first decide what kind of joints you want, and how you want to be able to adjust/tighten the control arm. Then find a brand that fits your preferences.

Comparing spacers to dual and triple rate springs is a stretch at best. I don't think people are overstating the need for track bars. People have posted pictures with up to a 1" shift. I totally agree about the jam nuts though.

 

[Uhdinator]

i would think a 2" spacer setup, and Rubicon high fenders would work fine for 315's.
Better shocks will control body roll a little better than stock with extenders.
Rim backspace needs to be less to avoid control arms and should have min 8" rim per most if not all 315 wide tire specs. if you have the plastic air dam things on the front bumper/fenders they will need trimmed too.
My 305/65's barely clear the bottom edge at full turn.

 

[shekmark]

-RC Vertex shocks. Best mod to the Jeep, barnone. They collapse the same as stock, but extend about 1.5" longer than stock, adding flex. The ride is great everywhere, just turn the clickers to your liking.

Do shocks like this help with body roll in corners ( street driving). I was under the impression that springs were needed to help control this as well. They are pricey at about 1500 for four. Overkill for street only?

 

[scrape]

Comparing spacers to dual and triple rate springs is a stretch at best. I don't think people are overstating the need for track bars. People have posted pictures with up to a 1" shift. I totally agree about the jam nuts though.

Please explain why you think a dual rate coil is any different than a spacer. Again, the top coil just blocks up under the weight of the jeep and serves no function other than to raise the ride height of the jeep and add uncompressed length to keep the coils seated with longer shocks. A spacer does exactly that.

As far as triple rate springs, I've seen a ton of marketing BS and uninformed comments about them over the years. Let's ignore the first of the three rates because that's just the top coils that block up, same as a dual rate spring. The 2nd and 3rd rates are where the nonsense comes in. I've seen people say that as you start compressing the 2nd (softer) rate, the 3rd (stiffer) rate starts to activate, giving you more support over large bumps and more stability in cornering. Sounds intuitive I guess, but that's not how springs work. Multi-rate springs will have a linear spring rate, calculated by 1/((1/upper-rate) + (1/lower-rate)), up until the point where the section of the spring with the softer rate is in full bind. That may happen in some racing applications, but probably not on the trail (at speeds where it would matter), and certainly not on the street. So the vast majority of people who have triple rate springs, guess what, I guarantee you've only ever felt one rate. Anyone who would really benefit from a dual rate (triple rate in this context) setup should be on coilovers, where you have total control over both rates, and can use the stop ring to set exactly how deep in the stroke you want the stiffer rate to take over.

So just to recap. A dual rate coil is a linear rate coil with a collapsed block of coils at the top acting as a spacer/helper spring. A triple rate coil is effectively a linear rate coil with a collapsed block of coils at the top acting as a spacer/helper spring. Your stock Jeep coil springs with spacers are linear rate coils with a block of plastic at the top acting as a spacer. And as long as that plastic spacer adds enough length to accommodate whatever shocks you're running, there is zero functional difference between any of these 3 setups.

Then as far as track bars. Either my measurements were wrong or whoever got a 1" shift has way more than a 2" lift. It's a basic pythagorean theorem problem. Let the hypotenuse (C) equal 34", the length of the track bar. Let (B) equal the vertical distance between the axle-side and frame-side track bar mounting points, which I have written down as 2". Then we can find (A), the horizontal distance between the axle-side and frame-side track bar mounts using the formula A²=C²-B². The change in this horizontal distance is how far your axle shifted.

If you plug 2" (the stock distance) into the equation, you get 33.94". If you plug in 7" (indicating a 5" lift), you get 33.27", a shift of about 3/4".

 

[word302]

Please explain why you think a dual rate coil is any different than a spacer. Again, the top coil just blocks up under the weight of the jeep and serves no function other than to raise the ride height of the jeep and add uncompressed length to keep the coils seated with longer shocks. A spacer does exactly that.

As far as triple rate springs, I've seen a ton of marketing BS and uninformed comments about them over the years. Let's ignore the first of the three rates because that's just the top coils that block up, same as a dual rate spring. The 2nd and 3rd rates are where the nonsense comes in. I've seen people say that as you start compressing the 2nd (softer) rate, the 3rd (stiffer) rate starts to activate, giving you more support over large bumps and more stability in cornering. Sounds intuitive I guess, but that's not how springs work. Multi-rate springs will have a linear spring rate, calculated by 1/((1/upper-rate) + (1/lower-rate)), up until the point where the section of the spring with the softer rate is in full bind. That may happen in some racing applications, but probably not on the trail (at speeds where it would matter), and certainly not on the street. So the vast majority of people who have triple rate springs, guess what, I guarantee you've only ever felt one rate. Anyone who would really benefit from a dual rate (triple rate in this context) setup should be on coilovers, where you have total control over both rates, and can use the stop ring to set exactly how deep in the stroke you want the stiffer rate to take over.

So just to recap. A dual rate coil is a linear rate coil with a collapsed block of coils at the top acting as a spacer/helper spring. A triple rate coil is effectively a linear rate coil with a collapsed block of coils at the top acting as a spacer/helper spring. Your stock Jeep coil springs with spacers are linear rate coils with a block of plastic at the top acting as a spacer. And as long as that plastic spacer adds enough length to accommodate whatever shocks you're running, there is zero functional difference between any of these 3 setups.

Then as far as track bars. Either my measurements were wrong or whoever got a 1" shift has way more than a 2" lift. It's a basic pythagorean theorem problem. Let the hypotenuse (C) equal 34", the length of the track bar. Let (B) equal the vertical distance between the axle-side and frame-side track bar mounting points, which I have written down as 2". Then we can find (A), the horizontal distance between the axle-side and frame-side track bar mounts using the formula A²=C²-B². The change in this horizontal distance is how far your axle shifted.

If you plug 2" (the stock distance) into the equation, you get 33.94". If you plug in 7" (indicating a 5" lift), you get 33.27", a shift of about 3/4".

No. You get much more down travel before unseating springs with well-designed dual rate coils. They don't stay compressed when drooping. Triple rate coils help with bottoming out when dropping off a large obstacle and high speed whoops. Yes of course coil-overs are better, but how much better is questionable. I agree nobody who stays on the road is going to benefit from dual/triple rate springs, but to say spacers do the same thing off road is a stretch at best.

 

[scrape]

No. You get much more down travel before unseating springs with well-designed dual rate coils. They don't stay compressed when drooping.

Forgive me for assuming you actually read my original post that you quoted:

Only difference between that and an actual spacer lift is the top coils will decompress when the jeep is unloaded, allowing for a much taller spring than stock + spacer, which allows you to run much longer shocks without limiting straps.

And my most recent post:

as long as that plastic spacer adds enough length to accommodate whatever shocks you're running, there is zero functional difference between any of these 3 setups.

I would address the other couple of points you just made but I'm not sure how constructive that would be. Happy jeeping.

 

[Brock9281]

Thanks @Roky and @rustyshakelford , appreciate the input. Going to pull the trigger on one of the kits first of the year, or if Brett releases his BnL special I may go that route.

What lift did you go with and thoughts?

 

[apb]

What lift did you go with and thoughts?

I went with the Rock Krawler 3.5" No Limits - Max Travel. A local shop works very closely with RK, so that swayed me in their direction.

No complaints with on-road manners and off-road it shines. Plenty of flex and clearance, can't go wrong with RK as far as I'm concerned.

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