I don't do GT5, but for proper sims I always do it pretty much the same way. I have a few test tracks that load different aspects of the suspension (lots of slow corners with fast direction changes vs. tracks with faster steady state corners and hard braking situations) that I'm familiar with.
I basically take the car out and first try to find the proper gearing. It's pretty easy to do, you just try to adjust the gears so that you stay within the powerband through corners, especially on the exit, don't have to change up right before a corner (unnecessary gear changes eat up time, it's better to make that gear slightly longer so you can push it until you reach the braking zone) and finally set up the longest gear so that you can reach the redline at or near the end of the longest straight (depending on the car you can go faster if you set the gearing a bit longer than that, works especially with cars that have lots of low end grunt put not that much high end power).
The suspension can be a bitch to set up, especially because you often get carried away and make too much and too big adjustments. Always adjust one thing at a time, drive 5-10 laps before changing anything again, unless it's obvious something works or doesn't work. Basic guideline: Softer suspension = more grip, harder suspension = faster reactions. Softer springs = more loading of the tyres during braking and acceleration and more body movement, harder springs = less loading of the tyres and less body movement ("how much the car will lean"). Softer (lower setting) slow shocks = faster body movement when braking or accelerating, stiffer (higher setting) slow shocks = slower body movement when braking or accelerating ("how fast the car will lean." Too stiff settings will cause the tyres to overload and lose grip suddenly because the weight can't shift gradually, but hits a "wall" in the form of shock absorbers. A softer setting allows the weight to move more gradually and gives better grip, but also takes longer to recover from). Fast shock settings are only really for mitigating effects from bumps. So usually if the car leans too much forward when braking, takes a long time to recover from it or is just generally unresponsive when changing directions I stiffen up the front, if I don't get enough grip and constantly lock up the fronts when braking I soften the suspension a bit to see it it helps. Same thing with the back, if I need good traction of the line I go softer and if I need faster reactions I go harder. You can also adjust the balance of the car with this. If you suffer from understeer, it means your rear tyres have more grip than your front ones, and you can either stiffen the rear or soften the front. Reverse for oversteer.
Camber can help with cornering grip, but extreme settings leave very little rubber touching the road surface most of the time. A good way to adjust them is to look at the tyre temperatures. If the outside of the tyre is noticeable colder than the inside and center, you have too much camber. If the outside get hotter than the inside, too little. Your aim is to keep a consistent temperature throughout the tyre. This also includes changing tyre pressure. Too much pressure and the center heats up more, too little and the sides heat up more. Caster will also affect this: More caster angle will give you more camber when turning than you get with less caster angle. So it can help in situations where tight bends demand a higher camber but you also have lots of straights where you want more of the rubber on the road for braking. If you have force feedback enabled caster should also make the steering heavier.
Anti-roll bars will reduce body roll even if your suspension is otherwise softer. Can come in handy. Again stiffer settings mean faster response and lower settings mean better grip. Haven't studied these as much and usually just go by feel.
Adjusting your toe-angle can help if your car feels twitchy on straights and when the front or rear doesn't want to react when entering a turn.
Basically the duty of suspension is mainly to maintain optimum temperature in the tyres. Too hard a suspension will cause abrupt load changes on specific tyres when the car is disturbed, heating those tyres fast. Softer suspension will make these weight shifts smoother and heat up the tyres slower. So try to set up so that your tyre temps remain in the optimal zone, and balanced between the fronts and the rears. More caster and camber usually give better grip when cornering, and are also used to heat up the individual sections of the tyre (outer/center/inner parts) more evenly, along with tyre pressure.
So yeah, that's about all I can say about that. I left out aerodynamics because they're pretty self explanatory. They do very little in slow speed corners but can greatly affect grip, stability and speed on faster corners.
Parks wrote:If the posts on this forum are any indication, the PD is like a Teebird with sunshine coming out of its butthole so hard that it flies faster.