FOR 3.5" lift install

[Tools R Us]

There are three basic, general principles in spring design:

The heavier the wire, the stronger/stiffer the spring, higher spring rate.
The smaller diameter the coil, the stronger/stiffer the spring, higher spring rate.
The more active coils, the less load you have to apply in order to get it to move a certain distance, lower effective spring rate.

Using these principles, the spring on the left will be stiffer, having a higher spring rate. This assumption is with the alloys being the same.

The spring on the right has a much longer free length, can be used with a longer shock without becoming unseated. It appears to have smaller wire and one less coil, it will compress further, be shorter when solid/coil bound, making it’s travel “sweet spot” longer.

Load bearing compression (automotive type) coil springs are designed to use approximately the center 60% of their available travel or deflection. The spring rate tends to be more constant over the central 60 percent of the deflection range. Because of end-coil effects, the first 20% of deflection range has a considerably lower spring rate. The final 20% of deflection shows considerably higher spring rate and the highest spring stress. In most applications bump stops are set so that the last 20% before the spring goes solid/coil bound isn’t used. If it is used the spring will be quickly fatigued, sag. So a spring with a longer free length and shorter compressed length will always have a longer useable travel range or “sweet spot”, netting more even tire to ground pressure on uneven surfaces i.e.. off-road.

If the pictured spring on the left is an OME 851, we know some of the specs, using those it has a useable travel of about 10.4” before unseat and a “sweet spot” of about 7.8”, well matched to the shocks that it comes with. The FOR on the right, we have no specs for, but appears to have one less coil, larger wire and about 2.5” longer free length, so the numbers would be something like; 10.6” of useable travel before unseat and 8.2” “sweet spot”.

 

[Tools R Us]

Spring selection is much a personal preference thing, users have many different uses, priorities. There is no magic “one type fits all spring”, they all have compromises. A great load carrying, high speed and/or road spring is not a great off-road spring and vise-a-versa. The “needs” for good road handling and low speed off-road capability are on the opposite ends of the tuning spectrum.

For good load carrying, relatively flat road, a shorter travel spring is perfect. They do a great job of controlling body movement, requiring less shock dampening, sway bar, etc to get acceptable high speed handling. Off-road they will cause more uneven tire to ground pressures on uneven surfaces and make transitions from off camber, wheel lifts, etc more jarring, abrupt.

For good slow speed off-road performance, a relatively long travel spring, that has even spring rate through as much of it’s travel as possible, is a great setup. This allows the suspension to easily move, keeping tires on the ground and maintain as even as possible tire to ground pressure for good traction and ride. If you allow the suspension to move off-road, the body will move more when driven at speed, easy low speed flex = high speed body lean. Requires more shock dampening, sway bar, etc to get acceptable high speed handling.

If your looking to buy a suspension setup talk to a couple of vendors that have experience with them. Then the best advice is to hookup with a local club and ride in a few rigs, in the terrain where you plan to drive and pick a setup that works for your needs.

 

[Nay]

There are three basic, general principles in spring design:

The heavier the wire, the stronger/stiffer the spring, higher spring rate.
The smaller diameter the coil, the stronger/stiffer the spring, higher spring rate.
The more active coils, the less load you have to apply in order to get it to move a certain distance, lower effective spring rate.

Using these principles, the spring on the left will be stiffer, having a higher spring rate. This assumption is with the alloys being the same.

The spring on the right has a much longer free length, can be used with a longer shock without becoming unseated. It appears to have smaller wire and one less coil, it will compress further, be shorter when solid/coil bound, making it’s travel “sweet spot” much longer.

Load bearing compression (automotive type) coil springs are designed to use approximately the center 60% of their available travel or deflection. The spring rate tends to be more constant over the central 60 percent of the deflection range. Because of end-coil effects, the first 20% of deflection range has a considerably lower spring rate. The final 20% of deflection shows considerably higher spring rate and the highest spring stress. In most applications bump stops are set so that the last 20% before the spring goes solid/coil bound isn’t used. If it is used the spring will be quickly fatigued, sag. So a spring with a longer free length and shorter compressed length will always have a longer useable travel range or “sweet spot”, netting more even tire to ground pressure on uneven surfaces i.e.. off-road.

If the pictured spring on the right is an OME 851, we know some of the specs, using those it has a useable travel of about 10.4” before unseat and a “sweet spot” of about 7.8”, well matched to the shocks that it comes with. The FOR on the right, we have no specs for, but appears to have one more coil, larger wire and about 2.5” shorter free length, so the numbers would be something like; 8” of useable travel before unseat and 6” “sweet spot”.

The spring on the right is FOR 3.5 and on the left is OME 851. The spring on the left is paired with a longer travel shock by .5" and has a design of 6" of up travel. The spring on the right has a design of 5" of up travel.

Nice writeup, BTW. Obviously not a good assumption on alloys being equal, though, that likely being part of the answer to to the questions being asked.

 

[Tools R Us]

The spring on the right is FOR 3.5 and on the left is OME 851. The spring on the left is paired with a longer travel shock by .5" and has a design of 6" of up travel. The spring on the right has a design of 5" of up travel.

Nice writeup, BTW. Obviously not a good assumption on alloys being equal, though, that likely being part of the answer to to the questions being asked.

Oops, a bit of dislexiea when I made the notes, I knew the FOR spring was longer and didn't recheck my work before posting. If you could measure the wire OD that would make the "guess" a little better. My guess on the FOR is 10.6" useable and 8.2" "sweet spot".

 

[Tools R Us]

Not flattening the last coil is less expensive/labor intensive way to make them, if your running them on the metal coil seats I don’t see an issue with them, it would cause issues with plastic spacers. In the off-road case it allows a slightly longer shock before unseating. It’s an unsupported tail, so theoretically has less spring rate, probably lays relatively flat to the spring seat when the spring is loaded and may account for some slight progressive effect.

 

[NorCalSam]

Nice writeup, BTW. Obviously not a good assumption on alloys being equal, though, that likely being part of the answer to to the questions being asked.

ditto on the writeup and explanation that makes a lot of sence however like Nay pointed out you did not consider the possible differences in the alloys or the way in witch te coils were formed. This would have to have an impact the springs performance.

But I really don’t need to have a scientific explanation for why it works. All I know is that it is much better both on and off road then what we had.

 

[Cruiserdrew]

But I really don’t need to have a scientific explanation for why it works. All I know is that it is much better both on and off road then what we had.

Except for the front end vibration...


Anyway, realize there is a good chance that you are experiencing a placebo effect. As long as you are happy with the ride and the height, then it's all good.

 

[Tools R Us]

Maybe if you payed him $40,000. I mean come on guys.

So, $40,000 for basic spring specs, not much greed going on there!

I don’t see the “need” for secrecy? If someone is equipped to make springs, getting the specs from an existing spring is trivial. For most spring specs are useless, but some can get some benefit, from knowing how the new spring characteristics compare to the existing before spending their$$$.

... however like Nay pointed out you did not consider the possible differences in the alloys or the way in witch te coils were formed. ...

We don’t know the alloy of either spring, most manufactures don’t publish it. Again it would be an easy exercise to get it. You would need a device to compress the spring, a shop press works well, a scale and a measuring tape. Compress the spring an inch, record the scale measurement, repeat until the spring is solid. Most design springs with software, so by entering the measurements that you know it will spit out the ones that you don’t.

But it’s a moot point, the last time that I checked into getting one set of springs wound, it was much more expensive than simply buying them. So the only reason to do it would be if you wanted something different, unique, if that’s the case the specs of other springs are relatively irrelevant.

 

[sleeoffroad]

Not flattening the last coil is less expensive/labor intensive way to make them, if your running them on the metal coil seats I don’t see an issue with them, it would cause issues with plastic spacers. In the off-road case it allows a slightly longer shock before unseating. It’s an unsupported tail, so theoretically has less spring rate, probably lays relatively flat to the spring seat when the spring is loaded and may account for some slight progressive effect.

Tools, good explanations. The above might explain where the progressive rate thing comes from. However I still don't see how that would really be that much of a difference in real life since it would only effect the spring at the point where it starts compressing after being completely unloaded.

My only thought on this is that they are running a soft spring and compressing the heck out of it and using the shocks to control the movement.

I would really like to see a set of FOR springs on a unloaded truck, then add bumpers and such and take measurements again.

Nay is one of the few that runs a "light" truck. Either his truck is not as light as we suspect, or his springs are a lot different to what Sam is running.

Again, I am not disputing that it might ride better etc etc. I am just wondering about the claims of it works on a light truck as well as a heavy truck. On the FOR site they now mention that the springs are "Manufactured with bumpers winches a expedition gear in mind."

Maybe what Nay is running is the anomaly and we are talking about apples and oranges.

Sam went to this since the OME spring did not work for the weight he is running. From your explanation above and the photo's of the spring, I would say that it would be a good offiroad spring and be pretty " compliant" however from our experience we have not been able to make a spring like that and maintain it's ride or load carrying capacity over time on a heavily loaded truck.

That said, we are talking about hot rolled springs and maybe there is magic in cold rolled springs or the alloy they are using that we don't know about.

 

[concretejungle]

But I really don’t need to have a scientific explanation for why it works. All I know is that it is much better both on and off road then what we had.

not trying to split hairs here, but didn't you just say in a post yesterday that you were very uncomfortable with the rig at the rubicon? Is this a result of the suspension, or just because it's a whale sized vehicle?

Did you take the rig though anything similar with the OME setup on so you can compare flex, body roll, ect.. to the FOR kit?

 

[landtank]

you know, I don't remember all this scrutiny of Christo's 4" springs when he made them available. People bought them, tried them and posted what they thought of them. Why do we suddenly need to put these springs under a microscope?

I've got Christo's 4" springs and I'm half tempted to give FOR a call and see about doing a direct comparison, he might have something.

 

[kwikrnu]

you know, I don't remember all this scrutiny of Christo's 4" springs when he made them available. People bought them, tried them and posted what they thought of them. Why do we suddenly need to put these springs under a microscope?

I've got Christo's 4" springs and I'm half tempted to give FOR a call and see about doing a direct comparison, he might have something.

For people stitting on the fence that would be great!

 

[Corbet]

I've got Christo's 4" springs and I'm half tempted to give FOR a call and see about doing a direct comparison, he might have something.

I'm a year away from lifting my rig, but as I'm trying to choose between the Slee 4" and the FOR 3.5+ please do.

 

[frankies off road]

you know, I don't remember all this scrutiny of Christo's 4" springs when he made them available. People bought them, tried them and posted what they thought of them. Why do we suddenly need to put these springs under a microscope?

I've got Christo's 4" springs and I'm half tempted to give FOR a call and see about doing a direct comparison, he might have something.

Make the call.

256-413-8300

 

[Nay]

My only thought on this is that they are running a soft spring and compressing the heck out of it and using the shocks to control the movement.

I would really like to see a set of FOR springs on a unloaded truck, then add bumpers and such and take measurements again.

Nay is one of the few that runs a "light" truck. Either his truck is not as light as we suspect, or his springs are a lot different to what Sam is running.

Again, I am not disputing that it might ride better etc etc. I am just wondering about the claims of it works on a light truck as well as a heavy truck. On the FOR site they now mention that the springs are "Manufactured with bumpers winches a expedition gear in mind."

Maybe what Nay is running is the anomaly and we are talking about apples and oranges.

Sam went to this since the OME spring did not work for the weight he is running. From your explanation above and the photo's of the spring, I would say that it would be a good offiroad spring and be pretty " compliant" however from our experience we have not been able to make a spring like that and maintain it's ride or load carrying capacity over time on a heavily loaded truck.

That said, we are talking about hot rolled springs and maybe there is magic in cold rolled springs or the alloy they are using that we don't know about.

I think you are getting close here. We need to step back a bit - my springs aren't an anomaly, they are the production specs. This is just about design, and there are load bearing limits. I don't believe you can just load this suspension to the moon and get magic, but the range seems very good and almost a year and a half later my four corners are still level and unchanged.

The idea that this is a soft supsension controlled by the shocks isn't terribly well played out by the fact that my valving is 168/73 (production rates are slightly higher), although that remains an intriguing concept for somebody looking to design a long travel suspension.

The premise of cold rolling is you are supposed to get a greater consistency of spring rate across the load range tolerance (unloaded to the point of overloading) and throughout the compression range - the design parameter for FOR's springs is less than 2% variance over the life of the spring. The spring manufactuer claims that coil spring variances can exceed 15%. This would clearly be important if you want to use a lighter duty coil in raw material figures for a heavier duty application.

I don't understand technically how this works, but this is what I understand - if you take a spring with a certain set of characteristics (alloy, diameter, wind spacing and slope, etc.), the "effective" spring rate will depend on the length of the spring. In other words, you can create the effect of a much stiffer spring by using a longer spring that retains the design characteristics of the shorter spring. I know what the design spring rates for these springs are, and they are not super soft, nor are they OME expedition heavy by any means. I also know at what rates they test out at a racing shop (and these two numbers are quite different).

The key that I would see is that by extending a lighter duty coil for heavier duty use, you need to have the alloy composition and manufacturing process to ensure durability, and that is what drives cost. Durability remains something only long term testing can prove.

I think that post on the "sweet spot" hit it on the head. I have found the point where my rear springs really started to overload a bit - it was towing a 5K trailer with four kids plus some gear in the truck. That's a seriously heavy load, but I'd need a heavier duty spring if that was a regular application (I'd also need a different truck or forced induction).

I'll be happy to take measurements - we can measure by simply having family members stand on the bumper to add or subtract weight. My rig isn't "light" - I have the 3rd row of seats, Christo's excellent step sliders, and keep some tools onboard. I just don't have the big winch/gear bumpers and accessories, but having my family and gear in the truck makes up for the rest.

 

[cpg]

the "effective" spring rate will depend on the length of the spring. In other words, you can create the effect of a much stiffer spring by using a longer spring that retains the design characteristics of the shorter spring. .

Same spring but longer with the same pre load would be softer would it not?

 

[NorCalSam]

not trying to split hairs here, but didn't you just say in a post yesterday that you were very uncomfortable with the rig at the rubicon? Is this a result of the suspension, or just because it's a whale sized vehicle?

Did you take the rig though anything similar with the OME setup on so you can compare flex, body roll, ect.. to the FOR kit?

What I said was...."I found that my 80 with a 2.5” lift and 33s and weight well over 7,000lbs to be way out of its element. It was fun but very stressful and a true test of man a machine."

I ran the con in 06 with the old OME 2.5"HD. The suspension did fine.

Yes... what I ment by that was just that....The truck is to low, to big and to heavy for this type of trail.....its my dd/expedition rid. not a "trail rig".

I think Alvaro said it best when he said..."driving the 80 thru the con is like driving a school bus thru parking garage."

Tree is testing the FOR kit on the con this weekend in the snow both ways. jk

My truck is not doing that trail again anytime soon......maybe the lake to the springs.

I can test it near by at the Greenhorn OHV area. It has class 4-5 stuff.

It is much better in all areas then the OME kit was.....period!

 

[NorCalSam]

Except for the front end vibration...


Anyway, realize there is a good chance that you are experiencing a placebo effect. As long as you are happy with the ride and the height, then it's all good.

placebo effect?

I know where you live, and If I were you I'd be sleeping under the 80 at night. I need to test something.


Sam

 

[FirstToy]

You guys know there are tons of threads on Slee's coils. They have been under the Mud scope. The difference is Slee will directly answer a question about it.
There are also claims of the FOR coils being progressive rate and comfortable empty or laden- which sounds interesting and great but then begs the questions of techical specs and further discussion as people want to know what this means exactly. If FOR doesn't answer it, than discussion happens.

I think it then makes your review of the product more important since this would be the most accurate info to date.

 

[Tools R Us]

you know, I don't remember all this scrutiny of Christo's 4" springs when he made them available. People bought them, tried them and posted what they thought of them. Why do we suddenly need to put these springs under a microscope?

IMHO, Slee somewhat gets a pass here due to his standing, reputation and participation in this community. IIRC his new spring release wasn’t a total bed of roses, there was critical questions, commentary. The difference was, he jumped in and answered them and before the release he explained the goals, uses for the new springs.

So IMHO it’s only natural to have more questions, critical commentary, etc of a relatively new, relatively inactive vendor over a well established known one?

I've got Christo's 4" springs and I'm half tempted to give FOR a call and see about doing a direct comparison, he might have something.

Do it, more comparison is a good thing.