So a buddy of mine that I’ve been helping out recommended that I put this up, so here it is. Before I start with this guide, I would like to remind everyone that though this is a guide meant for beginners, all can benefit from it as I will cover techniques for setting up a car. This can obviously help someone new to tuning, as well as someone looking for a new way to approach a current problem. For a quick background on me, I grew watching NASCAR since I was little and currently attend NASCAR Technical Institute so that I could better understand the sport I grew up enjoying. Therefor a lot of the information in this guide comes from classroom material from the only institution officially backed by NASCAR themselves.
Now before you go off and think to yourself “Oh great, an oval idiot who thinks he can go fast just because he likes endless circles”, let me remind you that you should either stop being intolerant or just stop reading this any further. There is no mechanical difference between a stock car, a prototype, or even your '94 Civic hatch. Sure, the engines are different, and so are the suspensions and bodies but once you quit being intolerant, you’ll see that they all adjust in the same way. Springs are still springs, adjustable wings are still adjustable wings, and all cars still have caster, camber, and toe. Also, before you start thinking “This guy is an oval idiot, what does he know about setting up a car to go left and right”, let me point out what I just said. Left or right, or even straight, these adjustments do the same thing.
Also, before I begin, let me say this. This guide isn’t a magical number guide. You won’t find in here what tire pressure your Mclaren P1 should be set at for Circuit de la Sarthe, or what your rear wing adjustment in your S2000 should be for your B class build at Bathurst. This guide is only meant to tell what each adjustment is, what they do, and some differences in game from real world application. The most important note to remember however, is that tuning a car won’t make you any faster than you already are. In order to make a tune to get the car faster, you must have control of the car. If you want that E21 to fly at Yas Marina, you must first be able to control and post steady times with the E21 at any track. This is also why you don’t see me at the top of the leader boards. I don’t tune for leader boards, I don’t follow the typical leader board lines, and I will admit straight up that I’m not the best driver. I prefer to race, not hot lap, and so my personal tunes fit my personal style. Hopefully this guide will allow you to tune for your personal style, whatever it may be.
Now that I have my little piece out, there are several parts to a car. There are several ways to build one. There are several ways to set them up. The possibilities of a tune are quite mind boggling because there are so many different ways and the combinations are pretty much infinite. There’s trailing arm eccentrics, wheel spacers, caliper offsets, Ackerman angles, so many things. Luckily, we don’t have to worry about physically building cars in this game, and we really only have to worry about 25 to 32 of them. Yay! 25 to 32 out of hundreds, but that’s still… Well… 32 at most things we have to worry about right? I mean there’s gear ratios, spring rates, tire pressures, caster… So much for the yay, right? Tuning a car can be a fun process for many, boring for others, but tedious for all. It’s really hard to tune the car if you don’t know what does what. Those 32 options? Well they really only come out to be 16, and these 16 are the ones that you need to know. Fret not, these are only what they do, and I will cover how to use them later on when I talk about how to tune the car.
Tire Pressure: Just as it states, this is the pressure the tire while it’s cold. As the car runs, pressure will build up in the tire due to heat, and luckily we can see that, via telemetry. How pressure affects the car though is how the pressure inflates the tire. Even though the tire is one piece of compounded rubber that has been formulated (and built, meaning it’s really not just one piece) to withstand high temperatures, it still flexes with movement. The smaller the pressure is in the tire, the more it’ll flex as it sits. The higher the pressure, it’ll flex more as it moves. With a lower pressure, the tire has the opportunity to grip more as there is more surface area against the track. With a higher pressure, there’s less surface area for the tire to grip, so while it’s moving it’ll flex more to provide different areas of grip which can allow for more speed, depending on the amount of pressure.
Gearing: This is simple gear ratio, and this is how it goes down. A gear ratio is a simple formula of two different gears. You have the gear that’s being driven and the gear that’s driving. To find the ratio, it’s driven over drive. So if you have a driven gear that consists of 100 teeth, and a driving gear of 10 teeth, it’s a ratio of 10:1. This means that it takes 10 revolutions of the driving gear to turn the driven gear 1 time. This creates a mechanical advantage to get the wheels to move without destroying the driveling. And each gear can be adjusted so that each one provides a different range of mechanical advantage. Now let’s say a theoretical engine in a rear wheel drive vehicle can rotate up to 10,000 times a minute. If you’re in 4th gear with a ratio of 1.00, that means the transmission is rotating the drive shaft 10,000 times a minute, and the drive shaft is what goes to the rear tires. So what prevents the rear axles from rotating 10,000 times a minute and not blow up? The final drive is what you change. When you change the final drive, you’re changing the gear ratio of how fast the output shaft in the transmission can can turn the axles. A higher ratio can give you more acceleration, while a smaller ratio can give you more speed. However, this isn’t always the case, as I’ll explain later on.
Camber: Camber is the angle at which the tire sits in relation to the car. When you look at a stock car for instance, you’ll see two things common with the front tires. The one on the left side seems to be angled away from the engine, while the right side seems angled towards the engine. Well you’re not imagining things, that’s actually how it is. As the stock car goes through it’s forces, it will want to slide up the track with high banking. The camber acts as a wedge against the banking so that as the car attempts to go up the track, the tire will get a full contact patch on the track, providing the best grip it can. But in FM5, we don’t have to worry about high banking very often, nor splitting the camber angles from left to right, but camber still acts the same when you’re putting a car through a corner. It’s going to want to naturally slide, and camber will act as a wedge to the track surface. Positive camber is measured at the angle away from the engine. The more positive the number, the further the angle is away from the engine. A negative number is measured at the angle to the engine. More negative camber, the more the tire is angled to the engine.
Toe: Well we’ve got the tire angled to or from the engine, and now we have what keeps the tire straight. Toe measures how far the tire is pointed from it’s center line. “Toe-in” is positive toe. “Toe-out” is negative toe. Positive toe is when the tire points to the inside of the car, and negative is the opposite. So how does that work then? Toe-in can help the car going straight down the track by keeping stable, allowing for more speed. While going through the corner, since the tires are already angled in, the car could turn better in the corner. Toe-out can cause instability down the straight, allowing for the loss of speed, but the car could turn better, since the tires will be better since it’s angled to the corner already. Confusing? Yes, though it’s better explained while setting up a car.
Caster: This can be a difficult adjustment to grasp, but the idea is simple. You’ll hear some people use a shopping cart wheel as an example, but I personally believe that’s horrible comparison, and it hardly explains what caster actually is. Now think of a bicycle. With a typical BMX bike, the handle bars are directly on top of the tire, and the tubes that steer the bike are vertical. With a typical mountain bike, the handle bars are behind the tire, and the tubes are angled back towards you. This is caster. The wheel of the tire connects to the chassis via the spindle, which is attached to the upper and lower A-arms (a typical racing chassis setup by the way) by two ball joints which are the rotational pivot points. The angle of these two ball joints lined up is caster. A positive caster is when the angle is pointed towards you, the driver while in the car. A negative caster is when the angle is pointed away from you. The mountain bike? Positive caster.
So that’s what it is, now what does it do? Well think of the bikes again. Which one is easier to steer? Well most people that never rode a BMX bike would say the mountain bike because it seems the BMX only seems like it would wreck when you turned it. Well as much as that is true, it’s just as false. Both bikes have the same ability to turn, but that ability differs at speed. A BMX is a trick bike. That absence of caster works because BMX bikes aren’t meant to go fast, and because of the slower speeds, the bike could pretty much turn on a dime. At higher speeds though, the bike runs the risk of losing control. The mountain bike with it’s positive camber becomes easier to turn, and allowing for more speed as it turns, and potentially better control. But if the caster becomes too positive, then the amount of control can go away and the car becomes harder to steer and will give you even less control of the car if you need to react quickly.
Anti-roll Bars: Better known as sway bars, they kinda sum up their purpose in their name. They’re meant to help control the roll, which is actually the sway of the car. There are obviously the front and rear, and that’s what they correspond to, the sway of each end. What exactly is sway when we’re talking about racing though? Sway is just a simple word to use instead of speed of weight transfer. There’s several other ways to adjust the sway of the car, and the game only works with a couple, but these two are simple ways to do it. For those who don’t work on cars, the sway bar works the same way in a race car that it does in your personal car. It’s a piece of metal that’s specially fabricated so that it can twist. Because of this, it’s actually a torsion bar, but because there’s many different types of torsion bars in a vehicle, “sway bar” is an easy way to determine which torsion bar it is.
Now how it works is simple. Depending on the size of the bar, the car will naturally sway the amount the bar allows. Think of it this way. Say you have a piece of cardboard tube, like the tube you have when you finish up the roll of paper towels in the kitchen. If you try and flatten it between your hands, it’s tough to crush. But if you grip it and twist, it flattens much easier. Torsion bars act the same way. The harder you grip and twist, the more it’s going to compact. Now imagine that cardboard tube was like a slinky. You’ve got it crushed up and it’s destroyed. But this is a slinky cardboard tube, so it unwinds and comes back to it’s original shape. A thicker bar is going to take more force to twist, so when the bar is done twisting, it doesn’t snap right back so easily. If a bar is too thin, it’ll twist more easily and could then snap back pretty quick.
Springs: Ah, the springs, a fun and often misconstrued part of the car. For common people that don’t know much about cars, the spring is often viewed as what holds the car up and allows it to move up and down. But that isn’t the case. So what does the spring do then? Well, in a really odd concept, pretty much nothing but just keep the car from slamming down to the ground. However, because of the fact that majority of race cars use a coil spring (which from what I can tell, FM5 uses a variable rate coil spring for their data), they’re very important. As the spring coil compresses, it exerts force on the tire. The number you see is the spring rate. Which means it takes that many pounds of force to compress the coil 1 inch. So a higher number means a stiffer spring, which in turn puts more force on the tire, where a smaller number is a softer spring, which doesn’t put as much force on the tire.
Ride Height: Somewhat self explanatory, this is the height of the car. What’s not self explanatory is where this measurement is taken. Ride height is typically measured at the bottom of the frame rails in both front and rear. The distance from that spot and the ground is the height, which means that just because the ride height means is as close to the ground as you can get it, doesn’t mean the rest of the car is at the same height. Typically a car that is low to the ground is a fast car, however that isn’t always the case in some applications.
Rebound: This is part of the shock. Well, not really part of, more like an action of the shock. Shocks are a device on the car meant to handle how a car moves weight around while moving. Rebound is the decompression of the shock. Think of it this way. As the car goes into the corner and you apply the brakes, all that weight is going to go forward, which is just simple physics. It’s Newton’s first law, the Law of Inertia. As the front end shifts forward and the rear end lifts up, there has to be something to ease the sudden weight transfer, and it’s not the springs (which I just explained). The rear shock will decompress, allowing the weight to be applied to the front of the suspension. Rebound is just an easier way of saying decompression rate. A smaller value means the shock will decompress faster, and a larger value will decompress slower.
Bump: Part two of the shock. If weight going up decompresses the shock, then the shock has to compress so that it can be ready for the next weight transfer, and this is what bump is. It works the same way as rebound, but just in the way of compression. As you go forward into the corner, the weight will transfer forward, and the shock will compress. Once again, smaller is a faster compression rate, more is a slower compression rate.
Down force: The opposite of lift. And I’m not even trying to be sarcastic here. This adjustment isn’t something on a real car that can just be measured easily. The front splitter and rear wing are typically adjusted by measurements of height and angle. Down force isn’t figured out until the team combines wind tunnel data with track testing data. Luckily, FM5 cuts out that entire process. So that leaves it to what down force actually does to a car. This adjustment is simple in that you only choose how much down force you want on that end.
Braking Balance: All this does is transfer the amount of pressure between the front and rear brakes. Really a simple concept. When you push down on the brake pedal, pressure goes to both sets of front and rear disc brakes. With more pressure to the front, the front brakes will start to apply before the rear brakes allowing for more weight to be transferred to the front of the car.
Braking Pressure: Again, a simple concept. When you push down on the pedal, and the braking balance gets distributed, this is how much pressure is going to be applied to the brakes.
Differential Acceleration: You’ll hear some say this is the most important adjustment ever made, while some say that it is what it is. It’s rare I see any actual description of what it does though. The funny thing is, this really isn’t something that’s a race only option. It’s just simple part choice of what you run in any car. When you accelerate, the tires are going to rotate at the same speed. Which is fine for going straight, but not in a corner. When you attempt to accelerate through a corner, the tires have to be able to rotate at different speeds so that the car can properly turn. All this does is allow you to change the difference in rotational speeds under acceleration.
Differential Deceleration: The same as what I just said above, except for deceleration.
Differential Balance: You’ll only find this in AWD vehicles, and here’s why. All it does is proportion how much torque is going to which end of the car.
Okay, so now we know what each adjustment is, and what it’s supposed to do on paper and in theory. Now we have to apply the theories of what they’re supposed to do so that you can get a car to do what you want it to do. Remember back when I said that this isn’t some magical number guide? Well here’s the full statement. There’s plenty of places to get setups for each track you’re looking for. There’s the forums here provided by Turn 10, and then there’s the huge contraption of every single thing ever conceived as an idea known as the internet and it’s infinite amount of web forums. Now while for some people, tunes found that way may work for them, and make others wonder how the hell the car can even go forward. Then there’s those that don’t have the time to make their
own, so they find a tune they can work with and go with that. Now there’s nothing wrong with using something that someone else made, in fact, it’s actually not a bad idea to try. But there’s always two problems when doing this. For one, it’s the internet, and unlike what our favorite blonde in advertising believes, everything on the internet isn’t always true. So just cause the person says “I can do xx.xx and hit xxx MPH” doesn’t mean you’re going to do the same because that tune was either made to make you intentionally slower (watch out for Admiral Ackbar, just sayin). And secondly, and 99/100 times the case, the tune was tailored to them, which means if you’re going to be faster with it, you’re going to have to change it (if you can change it of course). Now let’s get to changing it.
If you’re doing what I just stated and are changing a tune, just stick with me as I’m starting from the ground up for those who want to attempt their very own tun. But this can also help adjust different areas you’re wanting to look at. Also, this is the way I like to make my setups, and is also a common way I’ve found out, and is also a good stepping stone for developing your own way of tuning the car. The most effective way of making a tune is to have base process to create the tune.