I've been trying to figure out how to retain the good quality ride on the street while still having the increased spring rates. So I think the easiest way to do that would be to use a main/tender spring coil over setup with the threaded adjustable sleeves. Has anyone used this and if so what spring rates would you suggest? I'm thinking 400lb main and 250lb tender in front and 350 main 250 tender in rear.

 

If you are concerned with ride quality why not just get the Pro-kit or some H&R Sports, odecent ff the shelf shocks and call it a day? You still get a stiffer spring, a safe front-biased ratio and a decent ride....

 

I use 400# F and 600 # R on my Integra Type R with a 26 mm rear sway bar and find the ride very nice (using Bilstein dampers). I think a lot of the ride quality issues will be with the dampers and not so much the spring rate. The problem with high spring rates is that you have to use beefy dampers - and that combo usually results in harsh ride on uneven surfaces.

I noticed the ride got a LOT stiffer when I added a 6-point cage - which almost feels like an effective increase in springrate for what it's worth.

 

i think you should just get eibach pro kits. trying to mess around with dual rate springs for street is going to be a headache.

the problem with doing so is getting the preload right. because the natural corner weights of the car are not equal, each side will be preloaded unequally and thus have unequal distance to the "tender" spring is fully compressed and goes to the higher spring rate. this isnt so much of a problem with progressive springs, since the progression from the mixed spring rate to the higher spring rate (remember the combined spring rate in series is the inverse sum of inverse rates, so the combined rates will never be as low as 250 lb/ft) is, well... progressive. whereas with a "tender" spring the shift is immediate. may cause an imbalance.

so another big factor you have to consider in how this spring setup will perform is how long the "tender" springs will be. this will affect at what point in the shock travel the spring rate will switchover. but this limits the amount of ride height range that your "tender" spring will be effective.

all this combined, i think you need to just get eiback prokits....

 

I've tried several of the off the shelf spring kits and so far none have been to my satisfaction. They either don't drop the car enough or too much.

Your advice on the quality dampers make good sense and I did notice better ride qualities when I swapped in some new AGX's for the Illuminas I had on there for 90K miles.

I agree that the tender springs will be hard to set up for each corner given the different weights, it just seems like the way to go, rather than the straight rate springs that comes with most coil over kits...

After I put on the ITR front bar we'll see if I still need to tailor the springs to what I want. thanks

 

I am using 350/400 8"/7" springs with kyb agx shocks on my 00 si. The ride is not that comfortable unless i set the shocks on full soft but then they are too soft to control the rates. I would just go with a set of progressive rate springs if you want comfort.

They may just seem stiffer in my car since i have corbeau a4 seats. Stock seats might give a little bit more cussion.

 

A few questions:

Is this car used for competition? If so, what class? And how competitive do you want it to be? What is the current setup?

A few comments:

Tender springs are a bad idea for the previously mentioned reasons. Lower does not guaruntee faster. Stiff does not guaruntee faster.

Case in point:
SCCA DC Region Spec RX-7s. Run with Tokico Blues and cut (yes, I said cut) street lowering springs (not unlike Eibach Prokits, but linear). They handle very well. The key is a balanced setup that is easy to drive hard. Adding compexity does not make the cars faster except at the top of pack. Compare the SRX-7 times to ITA times (ITA is where the cars would run without their own class). ITA allows coilovers, tri-links, adjustable watts links, fancy shocks, adj swaybars. And, with all this stuff, the cars are only faster at the very top of the pack - there are many mid-pack SRX-7s that would do well in ITA against 'better' prepared cars.