Measuring leaf springs seems simple enough, doesn’t it?
The truth is measuring leaf springs can be tricky to somebody who hasn’t done it before. But with this guide, a measuring tape, and a set of leaf springs to measure, you’ll be off sending in the correct measurements for springs in no time.
The Wrong Way To Measure Leaf Springs
The wrong way to measure springs is eye to eye. You know, taking the tape and measuring the spring straight from one end to the other.
It’s wrong because springs flex up and down depending on the weight applied, which changes the length of the spring a different amount depending on the spring’s rate (and whether it was properly built.) So that method doesn’t tell you your spring’s size at all.
Worse yet, it also doesn’t tell you where your center bolt is located. The location of the center bolt is where your axle and spring meet.
Do I need to stress the importance of making sure your spring is connected to the axle correctly? No? Oh, good.
The Right Way To Measure Leaf Springs
You need to measure the spring as though the spring were flat. Relax, that doesn’t mean you need to learn advanced calculus. All you need is this handy picture and your own trusty measuring tape.
Divisional Length
- A.) Follow the curve of the spring, measuring from the center of the front eye back to the center bolt
- B.) Then, measure from the center of the other eye back to the center bolt.
- Record the length like so: “24 inches x 24 inches” or maybe “21 inches by 27 inches,” depending on your measurements and center bolt location.
These measurements are called the divisional length.
You see, when you give the length of a spring as two lengths going from the center of each eye to the center bolt, you kill two birds with one stone and give us the location of the center bolt as well.
Spring Arch
Spring arch is measured by splitting the center of the spring’s eyes with a straight edge. (Grab a yardstick or anything you can reasonably call straight.)
Don’t try and flip your spring upside down and measure that way.
I know it feels clever, but those pesky spring eyes just won’t let you do it. So take an extra step and measure it this way.
Your ride deserves it, right?
- C.) Measure from the line created by the straight edge to the main plate right next to the center bolt.
This is true no matter which way the spring is bending. So don’t fret if you get a negative number. It’s ok.
And that’s all!
That’s all it take to measure springs the correct way. See, that was easy now, wasn’t it?