///M-Specs Pocket Guide to GT3 Suspension Tuning This guide covers the fundamentals of suspension tuning for GT3. It gives you some important background information and hopefully will teach the beginning tuner how to make a car handle better. It presumes very little prior knowledge; so experienced car buffs may want to skip ahead to the Handling Problems and Solutions Guide. The tips in this guide are taken from real life tuning principles, but its important to remember that the GT3 suspension model is abstracted and grossly simplified compared to a real racecar. I also claim no special knowledge of the inner workings of GT3's physics modeling: I'm simply applying what I know about real cars to what you can do in GT3. In addition, I've also striven to ensure the accuracy of the information contained within, but obviously can make no guarantees as to the effectiveness of any proposed solution. In other words: I hope this information is useful, but Your Mileage (literally) May Vary. WHAT YOU NEED TO KNOW ABOUT TIRES Our discussion on tuning starts with the tire, because everything you will do to your suspension is for the sake of the four pieces of rubber attached at the corners of your car. Each tire can produce a tractive force (aka 'grip') that helps keep the car on the road. How quickly you can corner is dependant upon the distribution of work load to each of your tires. The goal is to make sure each of your tires is producing its fair share of grip to turn the car. When you corner, all the weight of the car will move to one side. Thus, the tires on the outside of your car will tend to take the brunt of the weight transfer. This is actually good to an extent, because a modern performance tire will produce more grip as you increase the amount of weight you put on it. The amount of downward force applied on a tire is commonly known as download. As download increases, a tire's tractive force will rise, allowing greater lateral acceleration (faster cornering). The ability to convert download into tractive force is known as a tires' coefficient of friction. In layman's terms, the better a tire can stick, the higher its coefficient of friction. The tire's ability to produce tractive force will peak at a certain point, however. After this point, it will drop off -- sometimes dramatically. When a tire gets to the edge of its ability to produce tractive force, it begins to slip. But a curious thing begins to happen at that moment: a modern performance tire grips best just as it begins to slip. Really. The amount of slip is commonly called the slip angle and refers to the angle between where the tire is pointing and the angle that the tire is actually moving in. The optimal slip angle for most performance tires are usually only a few (less than 10 but more than 1) degrees. There's a great deal of technical stuff available on why tires behave this way, but is outside the scope of this guide. Simply put, the harder you press down on a tire, the harder it grips, until it starts to give up and loses traction. Some tires grip harder in proportion to how hard you press on it. These tires are known as 'grippier' or 'stickier' tires. In GT3, you can help this simply by buying tires with a greater Traction number. Therefore, the goal of every race car driver and engineer is to put the stickiest set of tires on his car and get each of the tires on his race car to that magic optimum slip angle and stay there as long as the car is turning. Of course, this gets complicated in a hurry as we'll see soon in the next part of this series.