I'm still a little confused on this setup. I've mostly seen kits of gc jacks that come with shorter springs. Is there a kit that allows you to use stock length springs, or even eibachs etc for the front and rear. I guess that would have to work similar to an internal spring compressor tool.

I just bought new springs and would rather look into this before I bring out the cutting wheel (to drop it about an inch)

 

no, the jacks are adjustable perches, so the spring has to be shorter since the area where the spring installed is not growing larger.

you can use a stock spring, but it will have to be cut done a lot, and that will change the ride and rate of the springs. I used cut v6 springs for a little while and have to cut about 5" off them to use them with jacks. They were 14.88 free height IIRC, and i cut them to 10"

 

Ok that's how I thought the jacks worked. So I guess theres nothing that can work inside the spring to compress it safely for a 1-1.75" drop.

 

No, Those are dangerous to use and should have never been invented. They do not stay in place and they eliminate "free coils" which cause an unwanted increase in spring recoil frequency.

The key to a good coil spring choice is using a spring that is made for the ride height you desire with as many coil winds as possible within reason. Let me explain that better for you- he's an analogy:

Take a bungee cord that is 100 feet long and one 50 feet long. The guy jumps off a bridge witht he longer one and it will strectch longer and smoother until it recoils- it will take a longer time to go down and then back up before you start heading down again- this is frequency.....
...now...
...take the shorter 50 foot bungee and do the same. The bottom stretch impact will slow the jumper more abruptly and jarr him in recoil more harsh to spring him back up...AND it will do this in a much faster , shorter time frame until it cycles back to the downward stroke again and again. It has a higher recoil frequency that is not as smooth and more jarring or harsh.

Coil springs work in essence in this same fashion, only in compression and recoil rather than stretch and recoil. You basically want the coil spring to be made with the longest coil wire possible. Longer wire means a less steep climb in each loop of the coil as it gains in height. Too little climb angle and too thick wire though will cause the coil winds to make contact with eachother as the spring compresses- this is bad and called "coilbind" It deadens "free coils and will suddenly cause a spring rate to climb becasue you loose part of the absorbtion of the coil spring.

To make a long story short- go to this page and click to "Springs", then click to "front springs" Scroll down the page and you want the spring choices on the lower right of the page. We run 5 1/2" outside diameter springs. A 12" spring will make you car very low (about 25" fender height from ground the center wheel arch). Considering the weight jack takes up about 1", I would recommend you go to the 11" free height springs. If you have a V8 car then go to aprox 800 lb springs for a good street performance rate- about 900lbs for a good fulltime autox rate, and about 1000-1100 for a monster high speed road course full race car on a smooth high speed bank. (I would recommend you go to the 800-850 range for a daily driver car with a very sprited handling firmness.

http://www.bluecoilspring.com/

 

the springs are 10 to 10 1/2 inch tall and rated at 175lbs
see if you could just buy them..

GC sold me just the rear set up, jacks and springs. as im using coil overs in front.