Pirate 4x4 banner

1 - 12 of 12 Posts

·
Premium Member
Joined
·
3,444 Posts
Discussion Starter #1
I have some CO springs (2.5 id) various lengths, and there are no numbers to indicate what rate they are. I've searched and read BV's CO bible 1&2. How can I figure out what rates these are?
 

·
Registered
Joined
·
114 Posts
in order to do it correctly, you need a spring compressor or press of some sort. you need to compress the spring 1", and what ever amount of force it takes to get 1" is the spring rate. so if it takes 400#s to crush a 3"x16" spring to 15", its a 3x16x400
 

·
Registered
Joined
·
6,620 Posts
The description of how to do it based on the dimensions of the spring is in Part 1.

You can also do it by applying a known force (weight) and measuring the deflection (easiest if done vertical (perpendicular to earth's surface) so you don;t have to factor the IR.
 

·
Premium Member
Joined
·
3,444 Posts
Discussion Starter #4
Let me clarify better what I am asking:


The description of how to do it based on the dimensions of the spring is in Part 1.

You can also do it by applying a known force (weight) and measuring the deflection (easiest if done vertical (perpendicular to earth's surface) so you don;t have to factor the IR.
I did read this, an excellent tech article as always...Thank You! And I understand as well as my limited capacity will allow me.

in order to do it correctly, you need a spring compressor or press of some sort. you need to compress the spring 1", and what ever amount of force it takes to get 1" is the spring rate. so if it takes 400#s to crush a 3"x16" spring to 15", its a 3x16x400
This was also laid out in BV's article.

What I want to know is what PRACTICAL way can I do this without any calibrated measuring devices. I mean stacking 300 lbs on top of a spring is not going to be that easy. I don't have access to a press of spring compressor with any calibrations.
 

·
Premium Member
Joined
·
11,125 Posts
You don't need to be that scientific about it.

Find something that you know how much it weighs, put it on the spring, measure the deflection.

Hell, put the spring in a doorway and stand on it yourself. Use the door frame to balance while someone else measures the spring. Good enough for a ballpark estimate anyway.
 

·
Premium Member
Joined
·
3,444 Posts
Discussion Starter #6
You don't need to be that scientific about it.

Find something that you know how much it weighs, put it on the spring, measure the deflection.

Hell, put the spring in a doorway and stand on it yourself. Use the door frame to balance while someone else measures the spring. Good enough for a ballpark estimate anyway.
How far does it need to compress to get a somewhat accurate estimate. For example if I (220 lbs) stand on one of the 16 inch 2.5 spring it compresses about 1/2 inch. Does this mean its a 440 lb spring?
 

·
Premium Member
Joined
·
11,125 Posts
Of course the answer is only as good as the info used to arrive at it, but yeah, that's what you'd do.

The spring rate should be linear - i.e., a 440 lb/in spring takes 220 lb to compress half an inch, 880 lbs to compress two inches, etc.
 

·
Registered
Joined
·
192 Posts
If you have a set of calipers you could just use the equation from the same article (and in the spreadsheet) and calculate it. Nothing more than a couple of measurements and count the number of coils. It worked great for my springs before I found the markings.
 

·
Premium Member
Joined
·
3,149 Posts
Crude way but it should work. I used my race car scales but a good bathroom scale should do it. With floor jack lift truck up. place spring between bumper and scale. slowly lower truck on spring till you get 1 inch of compression read scale. Thats the rate. If you max out scale compress only 1/2" and double weight reading. This should get you in the ballpark.

Oh and if it shoots out it hurts...
 

·
Registered
Joined
·
6,973 Posts
Next time use a dremmel and mark the spring rate on both ends before installing them...or just buy King springs because that is how they mark all theirs.
 

·
Premium Member
Joined
·
3,444 Posts
Discussion Starter #11
Crude way but it should work. I used my race car scales but a good bathroom scale should do it. With floor jack lift truck up. place spring between bumper and scale. slowly lower truck on spring till you get 1 inch of compression read scale. Thats the rate. If you max out scale compress only 1/2" and double weight reading. This should get you in the ballpark.

Oh and if it shoots out it hurts...
I will try this, and hopefully not kill myself.
 

·
Premium Member
Joined
·
3,444 Posts
Discussion Starter #12
Next time use a dremmel and mark the spring rate on both ends before installing them...or just buy King springs because that is how they mark all theirs.
I bought these used and was told the spring rates were xxx, unfortunately when mounted one side sagged alot more than the other, after close inspection you could see that two springs were not the same. (the numbers were worn off when I got them)
 
1 - 12 of 12 Posts
Top