There are a lot of folks out there, bless their souls, who have bought into the craze of coilover suspensions without having full knowledge of what they are getting into.
This article is a shot-gun approach at dialing in your favorite coilover kit for the street. Aimed at our core market, front- & all-wheel drive Honda and Acura cars, primarily driven on the street. This is a really general methodology, but it works. People often get mixed up because the changes they make in the front or rear impact the other end of the car, and you keep chasing your tail. With this approach you get the front all dialed in on what is important there, and you can tackle how the rear reacts afterward.
The first thing you would do is set the preload back to zero and then move the damper adjustment knob in the front at least midway in its range, if not more stiff or almost full stiff. This will give the input control and sharpness of steering and handling you probably want. Less “bounce” per-say or “float” in the front end is desired. Those feelings give a certain distrust in the handling of the car and your ability to control it. Moving this stiffer should not adversely affect the ride at all although there will be more harshness through the steering wheel, firewall, and floorboard. It may seem that the car is transmitting more from the road, and this is a good thing. Dial it back to give more NVH isolation if needed, but keep it firm. You should not need any more preload here, but if the front end seems to feel like it bottoms out at all you can add preload about 1/4″ at a time until it feels a little better.
The ride quality and ultimate balance of the car is largely dictated by the rear setup. Here I recommend people make the damping as stiff as they can without feeling too much discomfort. Start in the middle and move softer if you need more comfort over bumps (you won’t be able to make it perfect over all bumps, you are going to have to find a compromise) or firmer if the ride is not uncomfortable. The firmer you make it the better the car is going to feel in a corner but will ride worse and worse. Ultimately you want to find where you are unable to accept the ride and dial it back a bit. In general, you want as much stroke in the back as you can get because this will allow a good ride and add grip, but want body movement controlled enough that it doesn’t feel like it is wallowing about. Preloading too much here, or putting stiff springs, is great for swinging the tail around an auto-x course, but makes the ride like garbage. Don’t preload the rear if you can help it, but again if the suspension seems to cycle too much even on firmer settings, add preload incrementally.
Spring rates and preload.
The only real reason to change rates is if you are exceeding the cornering load limits the kit was designed around. Springs are spec’d to hold the car up and to resist forces in cornering. A car with lighter weight will need lighter springs, and heavier cars need heavier springs. Also, a car cornering at .8g will not need a firm a spring as a car cornering 1g. I think a lot of people think that works in reverse…take an .8g car and add heavier springs to make it corner like a 1g car. Maybe this is true to a certain extent, but more important are the tires, tire pressure, road surface, and other grip related factors. Those all add grip. Firmer springs without more grip will cause the car to slide easier.
Wider tires mean more grip meaning harder cornering loads requiring firmer springs. Increasing the rates will allow the car to cope with harder cornering loads, but will dramatically impact the ride. This is especially true if the dampers are not tuned to accommodate these changes. Many adjustable suspension kits are designed around a single spring rate and allow some latitude up and down in spring rates but don’t mistake this as truly stiffening or softening the suspension.
Then there is preload, which is largely misunderstood. Changing the spring preload does not change the spring rate, but can lead to the effect of a firmer feeling suspension. Really what it does is it increases the load needed to compress the spring initially. Once the spring starts compressing it will feel normal but a larger input is needed to do that. This is particularly helpful bu increasing the amount of force needed to bottom out the suspension.
We hope that gives you enough information to get started on dialing in your suspension! By all means reach on out to us if you need more specific advice!