how are spring rates calculated ?

assuming two springs being the same height, how does one spring get a higher spring rate then the other ? or stronger than the other ?

does the higher rate spring have more wound coils ? or is the metal coil itself stronger than the other ?

As a spring maker, I can answer this.

The main thing that changes a spring rate is how much wire is used. Or if you want, how many coils it has. Also, diameter and wire thickness can change the out come alot.

In a regular closed ended compression spring the first and last coils are not counted in calculating it's rate. Only the inner coils which are called "active coils".

You make springs?  How about I send you a box of Tein S-Tech for Y33 and you mimic them, but make them about 1.5" lower and a little stiffer?  PM me if it's something you can or want to do.

[QUOTE=F.L.S.;144189]You make springs?  How about I send you a box of Tein S-Tech for Y33 and you mimic them, but make them about 1.5" lower and a little stiffer?  PM me if it's something you can or want to do.[/QUOTE]

Ha, I'm sorry but I make small springs for surgical devices and some automotive applications.

Getting someone to do that would cost alot. Even a basic spring that I do takes about 3.5 hours to set up. Let alone doing large springs like that. Very few places have machines to make springs that big.

thanks mowgli, doing something such as falk's suggestion would sacrifice strut rod travel right ? can a stiffer and stronger spring actually make up for the loss  of strut travel ?

theoretically it is suppose to right ?

[quote=MoWGLi;144206]Ha, I'm sorry but I make small springs for surgical devices and some automotive applications.

Getting someone to do that would cost alot. Even a basic spring that I do takes about 3.5 hours to set up. Let alone doing large springs like that. Very few places have machines to make springs that big.[/quote]

The only thing you will get out of it will be a more harsh ride. If you go up on the spring rate too much, then the shocks/struts will become almost useless as you will have less and less give in the springs.

Seeing as the shocks/struts are there to dampen the spring compression and decompression, having a stiffer spring would only allow the shock/strut to move slightly compared to a stock spring set up. 

I personally think it would be silly to try and make your own springs and come up with a ride that is as low as coilovers, but 100 times worse to ride in. If you want to go lower, get coilovers, springs are only a bandaid for a certain market, and with in the VIP crowd, they do not work.

I don't know, I've had springs that were lower than I had some coilovers and rode much better on other cars.  Anyhow, it was just an idea.  As my car sits, I'm ~2.5 - 3" lower than stock (I cut the Teins), on KYB SR Specials and it rides really good.