To round out the durability characteristics, our KW suspension also features a bump stop with an integrated dust boot to protect against dirt and debris. Each spring is coated for optimum corrosion resistance and is seated in between two completely corrosion resistant, polyamide composite spring seats that are reinforced with stainless steel inserts.
The guts from our hybrid set of KW coilovers, were borrowed from KW's Competition coilovers. So you might be thinking, “Instead of going through all this trouble, why didn't you just grab some of KW's Competition coilovers off the shelf?” This is because the KW Competition coilover doesn't use a stainless steel body and instead, uses a zinc plated steel body. Now you're probably wondering why the KW Competition coilover is made from zinc plated steel since I just spent the last couple paragraphs selling you on how durable KW's Variant 3 stainless bodies are.
Well, the answer is that the KW Competition coilover is designed for just that, competition. You see, the durability of KW's stainless steel Inox-line makes them great for a car that is going to see a lot of street duty. However, stainless steel is not the best material for a full race application since it has two to three times lower thermal conductivity than that of mild steel. This means that stainless steel transmits heat at a lower rate than that of mild steel. So why is this important?
As a car travels over a bump and the suspension's spring is compressed, kinetic energy is built up in the spring. After the wheel passes over the bump, the spring extends outward and releases a large amount of kinetic energy. It's the job of the damper, to convert this energy from kinetic to thermal. The thermal energy is then dissipated through the damper body into the airstream. Hence, the need for a damper made of a material with high thermal conductivity on race applications like the KW Competition coilovers that are going to see some serious track action and not tens of thousands of street miles. It's simply about picking the right KW suspension for the right application and ours just happened to involve a lot of salt. With that being said, back to the details of the KW Competition internals.
The KW Competition coilovers are a twin tube configuration with valving that is generally stiffer in both compression and rebound than the street based Variant III or the street/track Clubsport. Generally speaking, “stiffer” dampers respond to load changes faster whereas an under damped suspension will tend to react more slowly to changes. Poor transient response makes for a sloppy handling car that handles more like a yacht floating on an ocean, rather than a proper racecar.
KW Competition dampers also run higher spring rates due to their track only calibration. Stiffer spring need higher damping force. The stiffer springs and stiffer damping is designed to work with the stickier tires and higher speeds of genuine racing. The stiffer springs and damping are also going to be useful for our top speed runs as suspension movement can result in geometry changes and stability issues.