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post #1 of 13 Old 02-13-2014, 05:41 PM Thread Starter
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jk spring rate

ok i know my jk spring rate is 18 and 17 for the front and 57 for the rear but does that mean it is 57lbs/in?? isn't that really low my friend says his tj is 100lbs/in front 125lbs/in rear how is that possible being so much lighter than our jks
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post #2 of 13 Old 02-13-2014, 06:41 PM
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Originally Posted by Thomas3rdgen View Post
ok i know my jk spring rate is 18 and 17 for the front and 57 for the rear but does that mean it is 57lbs/in?? isn't that really low my friend says his tj is 100lbs/in front 125lbs/in rear how is that possible being so much lighter than our jks
Because your numbers are wrong
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post #3 of 13 Old 02-13-2014, 07:11 PM Thread Starter
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Because your numbers are wrong
Care to elaborate because that's not very helpful. I was told(my own search on also) that spring rate is the last two numbers on my jk coil tags.
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post #4 of 13 Old 02-13-2014, 07:23 PM
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Originally Posted by Thomas3rdgen View Post
Care to elaborate because that's not very helpful. I was told(my own search on also) that spring rate is the last two numbers on my jk coil tags.
Sorry, I should not have responded. If those are the numbers on your jk coil tags, they are not your spring rates. Not even close. The initial rate on my coil overs is just under 90 lbs/in with a step up to 200.
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post #5 of 13 Old 02-13-2014, 07:27 PM Thread Starter
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sorry i didnt mean to come off snappy i just reread that, =/ anyways ok how did you figure that out im at a loss here all i keep puling up is people saying the last two numbers is your spring rate but that cannot be right?
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post #6 of 13 Old 02-13-2014, 08:06 PM
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I think its an indication of the spring rate, the higher the number the higher the spring rate, however I don't think its the actual spring rate. Its useful for comparison of OEM springs, but I don't believe it indicates actual spring rate.

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post #7 of 13 Old 02-13-2014, 08:11 PM Thread Starter
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Well that's a start on figuring these out ha now to find the actual lb/in rate
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post #8 of 13 Old 02-13-2014, 09:16 PM
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http://www.bluecoilspring.com/rate.htm

there is much more tech on spring rates on pirate4x4. You could probably spend weeks reading about the how and the why over there.

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post #9 of 13 Old 02-14-2014, 06:31 AM
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When searching for spring rates myself, I have only come across one (JKS) that listed their 'rate'. It is for their J-SPEC coils and they are listed at 142.5 lbs. I was trying to find a soft coil but I can't really compare it to anything because I can't find any more numbers. It's tricky. I don't know if 142.5 lbs is soft or stiff.

2014 Anvil 2 door
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post #10 of 13 Old 02-17-2014, 03:27 AM
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Originally Posted by D1EHARD View Post
When searching for spring rates myself, I have only come across one (JKS) that listed their 'rate'. It is for their J-SPEC coils and they are listed at 142.5 lbs. I was trying to find a soft coil but I can't really compare it to anything because I can't find any more numbers. It's tricky. I don't know if 142.5 lbs is soft or stiff.

Teraflex's 2 door 2.5" front coils are 18.5" long and have a 170lb spring rate.

Rock Krawler's 2.5" "Triple Rate" coils are 18.75" long and have a "dead zone", a "soft rate" with 175lb spring rate, and a "firm rate" with a 225lb spring rate.
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post #11 of 13 Old 02-17-2014, 08:04 AM
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Slade

The reason we have the firmer secondary operating rate is as follows;

When hard cornering it sets up well for on highway use, but a major reason is off-road. When you get into high articulation situations, have you ever looked at how the coils buckle? When this happens, the spring rates drop off like crazy and they leave the vehicle almost lifeless. It is similar to a coil over and properly using the secondary lock out nut. It is all about getting the suspension dialed in for all conditions or as many as we can foresee.

If you want, articulate your Jeep as much as possible and take a look at the coils all the way around.

RK
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post #12 of 13 Old 02-17-2014, 03:44 PM
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Originally Posted by Rock Krawler Suspension View Post
Slade

The reason we have the firmer secondary operating rate is as follows;

When hard cornering it sets up well for on highway use, but a major reason is off-road. When you get into high articulation situations, have you ever looked at how the coils buckle? When this happens, the spring rates drop off like crazy and they leave the vehicle almost lifeless. It is similar to a coil over and properly using the secondary lock out nut. It is all about getting the suspension dialed in for all conditions or as many as we can foresee.

If you want, articulate your Jeep as much as possible and take a look at the coils all the way around.

RK


Since your coils are one size fits all (same coils for a 2 door and 4 door), are your spring rates better suited for a 4 door JKU or a 2 door JK?

Wouldn't the "Dead Zone" in your "Triple Rates" be counter productive to the purpose of your "Firm Rate" when it comes to buckling under compression?

The Dead Zone doesn't add any free length beyond a linear coil of the same labeled lift height but would increase the coils Solid Height which would increase the point the coil would begin to buckle.

Wouldn't reducing the coils solid height also reduce the coil buckle and need for such a high firm rate?

Why did you put the "Dead Zone" in for the 3rd rate since it doesn't add any additional length over a Single rate/ linear coil spring, the length it does add is "not the best option" for keeping the coil seated, but in turn increases the solid height/buckle under compression?


Quote:
Originally Posted by Rock Krawler Suspension View Post
It is our opinion that using a coil with basically a zero or very light spring rate to simply keep it seated is not the best option for tons of travel.
RK
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post #13 of 13 Old 02-18-2014, 06:40 AM
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Slade

Since the dead zone is already out of the equation when it comes to buckling (i.e. the coils are already fully compressed), it really does not factor in to it very much if at all. We do not have a huge dead zone as we have stated in several posts as well.

The rate transition between the dead zone and the first spec'd ride rate is where the 2 doors ride giving them a little extra height and a little softer rate at ride height. However, when they get into it, the firmer rate is still the same.

The buckling equation is merely a function of spring geometry so changing the solid height will have nothing to do with it. Free length of the coil versus mean diameter. The longer the coil is, the more likely it is to buckle. That holds true for all of us since we are all constrained to the same coil spring diameters or they will not fit in the vehicle. Coils spring in general get forced to buckle under articulation since the coil spring seats are forced out of their proper orientation.

This is good review material. It has been a while since we actually spoke about this stuff.

Slade, we are not trying to bust your stones at all. You have an opinion and are more than entitled to it, but when it comes to engineering facts, it is best to stick to the facts. Good luck with your build or whatever you are doing.

RK

Last edited by Rock Krawler Suspension; 02-19-2014 at 07:00 AM.
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