I'm beginning to believe that the degrees of rake between different JK's varies quite a bit. I've seen this discussed in many threads, but never very scientifically addressed. I think I've figured out a way to accurately measure the differences between different JK's. If other's are willing to participate, I'd be interested to find out what these differences may be.

The options that I've heard may effect spring rates are Model (X Sahara or Rubicon), Unlimited vs 2 door, hard top vs soft top and Trailer package.

Unfortunately, I didn't measure mine before I installed 1.75" coil spacers up front. My rear is stock though.

For measuring, I took a tape and placed the end against the upper shock mount bracket (see picture). Then measured to the center of the bottom shock bolt. The front and rear can both be measured this way. On fairly level ground, I measured both sides then took the average for the front then back.

Front Right 20 3/8" Front Left 20 1/4" Front Average 20 5/16"

Rear Right 19 3/4" Rear Left 20" Rear Average 19 7/8"

The difference between the front and rear of my rock slider is about 1/16", so almost perfectly level. I have found that level, my JK tracks better and is smoother to steer/drive on the highway.

My JK's details;

Rubicon, Unlimited, Hard Top, Trailer Package.

Front Average 20 5/16" (with 1.75" spacer)

Rear Average 19 7/8" (stock)

 

I'm looking at doing a FT 2"BB lift tomorrow. I will say mine sits pretty level right now. I'll get these measurements off mine before I tear in to it.
Sahara Unlimited Hard top w/18's, no tow.