Spring rates

Awesome to have a board to ask some questions on. i currently race a bomber class at Forida's Desoto speedway 1/2 mile med bank track. we have a 6" ride hight rule and cars average 3500 lbs, ran a chevelle last year but wasted 3 sets of springs cutting them trying to lower car. its off season and i'm building a olds and would like to have new springs put in 800lb left, 900lb right. does anyone know if there is an equation for how much a certain weighted car will drop in inches with a certain height and weight spring????. i really dont want to do the cut thing this year......thanks for any replys or actually any suspension advice for 76 olds (mostly must be stock), oh crap i just thought of another question sorry, how about some tricks for creating wedge without a frame shop bending frame???  ok i'm done promise  

My understanding is that if you have say a 500# spring with 10 coil and you cut it exactly in half you now have 2 1000# springs. Each coil carried 10% of the total spring rate.

So if you have 500# spring with 10 coils and you cut off one coil you increase the spring rate by 50# (10%). That 500# spring become a 550# by removing one coil.

Now you have a 550# spring with 9 (11.11%) coils. If you cut one coil out you now have something close to a 611# spings.

Now you have a 611# spring with 8 (12.5%) coils. If you cut one coil out you now have something close to a 687# spings.

Now you have a 687# spring with 7 (14.285%) coils. If you cut one coil out you now have something close to a 788# spings.

Now you have a 788# spring with 6 (16.666%) coils. If you cut one coil out you now have something close to a 915# spings. Now if my math were perfect this should be 1000# but you get the idea.

Now that is very rough and you'll need to rate your springs on a spring rater to know for sure but this method will get you in the ball park.

Good luck!  

I agree with Modracer33. If you need to lower the car, find out how much and buy a spring with a lower rate than you need by the same amount that you will be reducing the length and increasing the rate. You might have to do a little (or a lot) of math, but you can come up with a correct starting spring rate so you can end up with the rate you desire at your new ride height. Many racers get this wrong and end up too stiff.