Subject: GT Tuning FAQ (long) From: email@example.com (Jet Jaguar) Date: Mon, 15 Jun 1998 06:15:36 GMT Newsgroups: rec.games.video.sony, alt.games.video.sony-playstation Gran Turismo Tuning FAQ By: Bob Chmilnitzky a.k.a. "Jet Jaguar" Introduction The reason I'm writing this FAQ is to help others make intelligent, informed decisions concerning car setup. I've found this area of the otherwise excellent Gran Turismo manual is sorely deficient. This FAQ is based on real-life car physics. This may or may not apply to the game, depending on how accurately the game depicts car physics. Any areas that I feel I have found to be different are noted in brackets, though the real-world effect is still listed for the sake of completeness, since I haven't sat down and tried everything out to see if it works (or in case I'm wrong :-) ). It should also be noted that my real-world experience is limited to rear-wheel drive cars, so any special considerations that need to be made for front- and four-wheel drive vehicles is not mentioned, but, from what I understand, the basic principles of setup are the same. Feel free to use this FAQ on a web page, as long as you let me know first. Also, I don't feel it is quite finished yet. I would have liked to have talked about dynamic camber changes caused by suspension movements (a.k.a. double wishbone suspensions: why you need them, and why everything else is junk :-) ), expanded the section on gearing, and added a troubleshooting section (i.e. if your car understeers while exiting corners then do this... type of thing), but that's not gonna happen any time soon, as I'm just too busy at the moment. In fact, I've been sitting on what I've got here for the better part of a week already. *sigh* :-( [Tip: Make one adjustment at a time and test it. If you make several adjustments at once, it can be difficult to isolate the effects of each adjustment, as one adjustment can cancel out another.] Springs: The purpose of the springs is to control wheel movement and keep the tyre in contact with the road over bumps and undulations. Stiffening the springs front and rear will reduce body roll and make handling more responsive, but cause a loss of traction over bumpy surfaces. Likewise, softening all of the springs will give more grip on bumpy tracks, but increase roll and reduce responsiveness. You can also use the springs to affect the car balance. You can reduce oversteer by stiffening the front springs or softening the rear. Likewise, you can reduce understeer by softening the front springs or stiffening the rear. However, be advised that changing just one end also affects fore/aft weight transfer. By softening the front springs, you'll also get more dive under braking. Softening the rear will give you more rear weight transfer under acceleration, which can give you more traction on the rear wheels in straight-line acceleration. [Tip: I generally do not use the springs to adjust balance, because of its effects on fore/aft weight transfer. I reserve the stabilizers for this purpose.] Ride Height: A lower ride height lowers the center of gravity, which reduces weight transfer during cornering, acceleration, and braking. The reduced weight transfer improves cornering. A lower ride height also lowers drag at high speed because you are presenting a smaller frontal profile to the airstream. Also, by lowering the front end and raising the rear, you can improve high speed stability and increase downforce by preventing high-pressure air from building up underneath the nose of the car. [Note: I have not noticed ride height affecting aerodynamics at all in the game] If the car is too low, it can bottom out, though this can be eliminated by stiffening the springs. For rear-wheel drive cars, you can improve rear traction under acceleration by increasing ride height, since maximum traction can be obtained with the maximum amount of weight on the rear tyres. Generally, you'll only want to do this in the acceleration tests, since it will hurt cornering performance, and never with front-wheel drive cars, since the driving wheels will be losing grip. Dampers: The purpose of the dampers (also called shock absorbers) is to dampen the oscillation of the springs. The shocks not only dampen spring oscillations, but they also affect handling during transient conditions (such as the entry and exit of turns), but not steady-state conditions. Softening the dampers reduces responsiveness, and likewise stiffening the dampers will increase responsiveness. However, if they are too stiff, they can lead to a loss of suspension sensitivity and increase the harshness and bumpiness of the ride. If they are too soft, it will cause the handling to feel mushy. You can reduce understeer during corner entry and exit by softening the front dampers or stiffening the rear. Conversely, you can reduce oversteer in the entries and exits by stiffening the fronts and softening the rear dampers. Camber: Camber is the angle the tyres make with the road and is measured in degrees. Tyre grip varies with the camber angle, and ideally is maximum when the angle is zero. However, the maximum grip is found with a small amount of negative camber because of tyre sidewall deflection (when the top of the tyre is tilted inward it is called negative camber. The game does not allow positive camber, and in real life it is never used). Also, as the body rolls in a turn, the suspension movements themselves causes some adverse camber change. These combined effects mean that for maximum cornering power you need to have some amount of negative camber. [Note: Unfortunately, I have not found a reliable way in the game to determine the optimum camber settings. In real life, camber is generally determined by measuring tyre temperatures at different points across the tread surface, or by monitoring tyre wear. Generally, I just play around with the settings until I come across a setting I think feels best.] Stabilizer: The purpose of the stabilizer (also known as the anti-roll bar, or anti-sway bar, although I prefer anti-roll bar because it can very well destabilize a car and has nothing to do with sway) is to resist body roll in a turn, much like a spring. However, unlike the springs, they do not come into play on two-wheel bumps or on fore/aft weight transfer. Stiffening the stabilizers front and back gives more responsive handling and less body roll, but can upset stability on a bumpy track by transmitting loads from one-wheel bumps to the opposite wheel. Likewise, softening the bars all around can increase body roll and reduce responsiveness, but make the car more stable on bumpy tracks. Because the anti-roll bars are fairly independent of other chassis settings, they are ideal for fine-tuning car balance. You can reduce understeer by softening the front bar, or stiffening the rear. You can reduce oversteer by stiffening the front bar or by softening the rear. Brakes: The brake balance allows you to adjust the proportion of braking power distributed between the front and rear brakes, which affects the balance under the car under braking. Oversteer under braking (i.e. the back wants to jump out while braking) can be reduced by increasing front brake balance, or reducing rear balance. Understeer under braking (the car doesn't turn in) can be reduced by decreasing front brakes, or increasing rear. [Tip: generally, you always want higher front brakes than rear. This is because of forward weight transfer under braking. As the weight is transferred forward off of the rear tyres, they are unloaded and lose grip, which causes them to lock up before the front tyres.] Gear Ratio: The purpose of the gearbox is to keep the engine within it's optimum rpm range over a range of road speeds. Shorter gear ratios (bigger ratio numbers) give you more acceleration and rpms. Taller ratios (smaller ratio numbers) give you higher speed before the engine redlines, but less acceleration. The final drive ratio can be thought of a sort of "multiplier" that affects all of the gear ratios simultaneously, which makes it convenient to fine tune your transmission to different tracks. [Tip: The way I generally set up the gears is to first set 1st gear so the engine rpm is in the meaty part of the torque curve for the exits of the slowest turns on the track. I then set top gear for top speed and space out the rest of the gears evenly between the two, except for the top couple gears, which I space a little closer together than the lower gears since acceleration is slower at high speed due to increased air resistance. I don't normally change gear ratios from one track to the next, I just set a good compromise and stick with it. The only exception is I'll sometimes adjust the final drive ratio at certain tracks. For example, at the Autumn Ring I'll bump the final drive to a shorter ratio to get more acceleration since you won't be hitting top speed anywhere on the track anyway, and on the oval track I'll change to a taller ratio to get more top end speed.] Downforce: Downforce is the aerodynamic force pressing the car down on the track and improves cornering grip. This downforce is dependent on forward speed, and increases as you go faster. Increasing the downforce all around increases cornering speed, but also increases drag, which gives you slower straightaway speed, and you may also need to increase ride height and/or spring stiffness to prevent bottoming. Likewise, decreasing downforce gives you lower cornering speeds but higher straigtaway speeds, and allows you to run softer springs and/or a lower ride height. [Note: I find downforce has only a small effect on drag. For example, in the Viper GTS on the top speed test, the difference between maximum and minimum downforce top speeds is only about 5 mph (8 km/h).] Also, you can also use downforce to fine-tune balance at high speeds. To reduce understeer, increase front downforce or reduce rear. To reduce oversteer, decrease front downforce or increase rear. Keep in mind that these adjustments are dependent on forward speeds and has less effect as speeds drop, so you can use this to give the car different handling characteristics for different speed ranges. --- Bob Chmilnitzky, a.k.a. Jet Jaguar To reply, do dental work on my address and pull all of the teeth. MSTie #54297 The Face on Mars issue is dead. Deal with it, and move on.