Why doesn't anybody else run them? They work great!...

What... I think my King Coils work fine!

Just out of curiosity, what spring rates are you running?

I'm really tired of the drunken goat handling of the 300 pounders that come in the Calmini kit. Was thinking of upping the spring rates a bit.

I've been running mine for years!

No issues with mine. I have a 250lb spring rate.

Mine are 300 pounders.

250 pounders will handle worse for such a heavy vehicle.

Swaybars(which I don't have) and good shocks are key.

If you have Sway-Away or Fox your spring rate doesn't mean much...

What is the total springrate you guys are running?
600lbs, 650 or 700?

I don't understand what you're asking.

There is no "600" or anything close to it in the spring rates.

King coils with Fox shocks here.

600 lbs. is the spring rate Total Chaos reccomends for their LT kit...

And the guy running the SLR long travel said that 650 lbs. wasn't giving enough lift on his, so he was going up to 700 lb springrate coils.

Which was why I was asking what people were running on their SASed trucks too.

I think you misunderstood.
If you are running Dual spring rate coils (2) springs per coilover shock stacked, then you are probably running (2) 300lb coils, totaling 600lbs like the Calmini SAS kit suggested.

I'm looking to run a single coil spring for my coilover swap for simplicity and since I'll be running less travel, so
it will either be 600, 650, or 700 lbs. total spring rate.

So, What is the springrate you used?

That's what I'm trying to explain. The spring rates do not add.

I would certainly expect the IFS system to run a much higher spring rate because the fulcrum of the control arms is so close. On a straight axle, there isn't so much leverage on the springs, making the spring rates much lower.

I believe mine has a 300 and a 250 on each shock. The effective spring rate is probably about 270. I'd be better off with 2 300's IMO.

Ok, that makes sense.
Does that mean if I went with dual rate springs I'd need two shorter springs between 550-700 lbs each?

You probably won't need dual spring rates for IFS. The reason people use them for SASed rigs is because having a higher spring rate on the upper spring gives a little better ride height adjustment range. An IFS setup (like TC) should be about right if you follow mfg's recommendations.

Sounds good. Thanks

The spring rate= (AxB)/(A+B). So (250x300)/(250+300)=137lbs/inch of shock travel.

Each coil is rated at so many lbs per inch. So when they get stacked, both compress less to make an inch of travel on the shock.

If they both compressed an inch the shock would travel two inches.

Ryan, I don't think that's right. The springs will travel based on force. So I would expect a 300# and 250# pair to compress proportionally for a combined spring rate of ~270#.

Here are a few links....

This is from the Poison Spyder Customs site:

For figuring spring rate with two coil springs- (dual rate setup)
(spring rate 1 x spring rate 2) / (spring rate 1 + spring rate 2)

Example for calculating the overall spring rate in a dual rate (two coil) setup:

Spring 1 = 250 lb coil
Spring 2= 300 lb coil

rate= (spring rate 1 x spring rate 2) / (spring rate 1 + spring rate 2)
rate= (250 x 300) / (250 + 300)
rate= 75,000 / 550
rate= 136.36 lbs

Your actual spring rate with a 250 lb coil and 300 lb coil is approximately 136 lbs; remember that the force on the coil is divided between the coils which is why the spring rate is a lower number than the actual individual coil rate.

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FOA's calculator-----> Clicky
This one is kinda fun to play with.
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Rancho's resource-----> CLICKY
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These equations seem to make sense. However, a K-value of 136 won't hold up my truck! Let me think.

If I have 2 300# springs end to end, they will compress equally. So if I apply 600# to one, will they both press 1" each or 2" each?

Top <==600 600==> <==600 600==> axle

It seems to make sense that BOTH must compress 2 inches. I'm just having trouble believing it!

Each spring sees the full force, but they share the travel. Crazy thought....

It takes a given amount of force to hold up your X. It doesn't matter which spring you use to do it, they will all be setting there holding up so many pounds. With 137 lb springs it will take longer for the spring to ramp up to that given value. Thus the reason coil-overs travel so much better. The one calculator above is kinda neat being a person can choose how much % of spring one wants to use at static height. The hard part is finding out how much the truck weighs minus the axles, tires, etc. (unsprung weight).

Yeah, when I really do the math, I guess 1100 lb will compress the 12", 250# by 4.4" and the 10", 300# by 3.7". So I'm using ~8.1" out of 13-14" (22-8or9) of total compression. That's puts me right at ~5" of my 10" of travel.

Funny to think the thread started out talking about 700# spring rates and ended at 140....

So you guys are all pretty much running approx. 300 pound spring rates, or thereabouts? No ones bumped them up a bit?

We've got the Fox coilovers with 300 lb. springs as they come from Calmini and while it flexes and droops out fine, it really rides like shit on the highway. I mean, like we're compensating with the turnsignals for the handling characteristics. No sway bars, and the steering needs a good going through after being wheeled for the past 1.5 years or so.

We did have one shock blow its guts out and had that rebuilt. Limiting straps were added to keep things from getting damaged from overextension. It was better for a while, but now it's back to its old ways.

This conversation now has me thinking that there might be an issue with the shocks/valving themselves.

I think I might bump up my tender spring to 300. I probably can't go much higher than that without raising the ride height.

You're barking up the wrong tree there man. The key phrase in your statement is "no sway bars" Have you ever driven ANY vehicle without a front sway bar? It doesn't matter what the spring rate is, it's gonna handle like shit on the highway without a front sway bar...

37" off-road tires (ballons) on 15" rims, 8" of suspension lift and several hundred pounds of Shrockworks steel have more to do with affecting handling than the absence of an anti-sway bar.

I wouldn't say it handles poorly, however, you must be much more attentive because emergency avoidance is drastically affected.