Spring rates by coil wire thickness?
 

So I just swapped the OEM MY00 springs for some H&R sports. I wanted to drive it but its still raining here in NE. I choose H&R because of the minimal drop and I got a great deal on them. I love the oem handling and would just like to maintain that with a little more roll rate and lower ride height.

H&R does not post spring rates. I measured the coil wire diameter on the oem springs and the H&Rs. Can spring rate information be extrapolated from this information? Here is what I found (inches)...

MY00 Front .455 Rear .495
H&R Front .500 Rear .505

So my interest is in spring rate balance front to rear. Clearly the measurements support the known fact that MY00 rear springs are stiffer than front. Does the H&R numbers mean the rate is similar front to rear? I guess the question is, what else affects spring rate?

Here's a link to a spring rate calculator; http://www.speed-wiz.com/calculation...alculation.htm

If the H&R springs are the same coil diameter and shape as OEM, then the formula will be fairly useful.

Caveat; This is only valid if the coil spring is the same diameter for all coils and space between each coil is even. If the springs are "bee-hive" design (coil diameter is small at the ends and bigger in the middle) or "progressive" (several coils are closely spaced with others farther apart) there are more factors that affect the spring rate, and whether it's linear or progressive, and if it is progressive, what the "rate of rise" and overall spring rate is. The calculation is also very sensitive to coil diameter, so that small measurement errors or even differences in paint thickness can induce large errors.

Interesting...

I did not measure the coil diameter themselves... The all looked the same. There did not to appear to be bee-hiving.

A spring is the same thing as a lever, it is just coiled. So material, diameter, and length are the deciding factors in rate.