Coil spring wrap count

I have a question, this post below was an old post I found when doing research for counting the wraps on coils, I know stiffness and softness has alot to do with things but the coils below are 9" Rustys coils and the guy counted 12 wraps...

The wire is .719 dia. and the free length is 23.5". I count 12 coils? Starting at the bottm end wire to the top right? I'll send a pic.

I should have them on tomorrow or Saturday.

Brad

Click to expand...

Well I have these coils below and my buddy gave them to me and told me they are for an XJ and they are 4" Tomken coils "he thinks", but when I count the wraps like that guy did I get 12 wraps also, I know the spring rate has alot to do with It and Tomken is known to be stiffer then some of the softer springs, but what do you think? Can both have 12 wraps and one be 9" and one be 4", my 3" Rough Country springs I have on my XJ now have something like 9-10 wraps at most

Yes, they can both have 12 wraps and give different lift heights. Here's some Rubicon Express 4.5" ZJ coils next to Skyjacker 8" XJ coils...

...the RE 4.5" ZJ coils with a 2" spacer give about the same amount of lift as the 8" Skyjackers but the Skyjackers have a much stiffer spring rate.

ok thanks, I was selling these 4" coils cause I dont need them but I was makin sure I aint screwin myself because I am in need of 5.5-6.5" coils and I didnt wanna sell them If they were the size I needed and my friend didnt know what he was talking about...Thanks :sunshine:

The formula for spring rate is : Rate=Gxd to the 4th power devided by 8NxD to the 3rd power; the "x" implies multiply.

The "G" and the "8" are constants for ALL coil springs made from steel. The "d"= wire diameter in inches
The "D"=mean coil diameter in inches
The "N"=number of active coils--coils that can compress or extend. A coil that is flat on one side or bent to lay against an adjacent coil is not active.
The "G"=11,250,000_torsional modules for steel).
From the formula, you can see that changes in wire diameter (d) and mean coil diameter (D) have a large effect on spring rate;i.e., how far the spring will compress initially. Thus, two springs with the same active coil count and overall length but with different wire or spring OD, will result in different ride heights (I think).

holy shyt, lol I failed algebra in highschool, took me two trys, and always sucked at any kind of math but thanks for your formula!

Looking at Jes's pictures, the 4.5RE coils are made of thinner wire than the 8" Skyjackers. Looking at the formula for spring rate, it's clear increasing wire diameter ("d" in the formula) is going to significantly increase spring rate.