Springs: What Do They Really Do? An Insight Into Tuning
Daily Slideshow: Spring rates are a vital part of car setup. Do you know what they really do? Let’s take a look at some things you might not know about this common modification.
Determine Wheel Rate
As a Professional Driving Coach for Porsche North America, a graduate of the Nascar Technical Institute, a mechanic, and track racer, I have spent thousands of hours spinning my wheels on the track. Experience has taught me that if you want to compare spring rates to another car, you can’t simply use the lb/inch rating provided by the manufacturer. All cars have suspension systems that work springs differently. This is where wheel rate comes in. By dividing the spring rate by something called motion ratio you can come up with a way to universally compare spring across various automotive platforms.
Balance The Car
Springs actually balance the handling characteristics of a car. If you jack up spring rate in the rear, you may begin to induce oversteer where the car was settled before. Conversely, a car that is under-sprung (or unsprung) will handle like a boat and can be downright dangerous. As your tire grip goes up so does the demand a suspension system requires of the spring rate to keep the same balance. It’s always changing depending on grip.
Work in Tandem With Shocks
Springs and shocks go hand in hand. While a spring's job is to soak up bumps, the shock's job is to return it back to its original state neither too quickly, nor too slowly. Once reasonable spring rates are determined, you will want to use sway bars to fine-tune your setup. Over-springing a car without upgrading the shocks is a recipe for disaster. It is also a way to run higher spring rates that don’t feel as harsh.
Help in Weight Reduction
Springs often come in smaller diameters, which can mean saving precious pounds to some racers. If you are trying to go for a super lightweight build, do not discount the spring as part of the equation. Having said that, do not buy cheap quality springs that will eventually sag causing you problems. Opt for high-quality springs if you’re going to reduce weight. Corvette Forum offers a lot of suggestions when it comes to springs and suspension setups in general. This thread is a good starting point, but there are many others.
Aero Affects Everything
If you throw effective aerodynamics onto a vehicle, your spring rate will likely need to increase. This is all well and good on a super smooth race track, but cars that see double duty don’t get the luxury of these glass surface roads. In the real world, we have to deal with bumps that make stiff springs unsafe. Understand that you can’t do both when it comes to high-performance and stability on real-world roads. A compromise will ultimately be slower in both environments than chasing a clearly defined goal.
In Closing
Springs do way more than just keep a car flat in the corners. They also do a lot more than simply lowering a car for a better center of gravity. These are dynamic tuning instruments that make up one piece of the tuning puzzle. Understanding the principles of what makes a car fast—sticky tires, aerodynamics, good balance, etc.—will ultimately determine what direction your mods need to go in. Good luck and comment below with any questions or additions.
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