I don't understand how many parts of tuning works.

[MIE1992]

I feel like the in-game descriptions in GTS are cryptic trash that doesn't tell me enough about how each setting works. For example, for the anti-roll bars. I saw someone's tune for the 330 P4 for the latest time trial, and it has the anti-roll bars set to ten on each end. I don't understand why, because I would've thought you'd want to tune the anti-roll bars to prevent oversteer, which is something I'd imagine the 330 P4 would be vulnerable to given its engine layout.

I have no idea how to tune the suspension, or even what various settings do like the compression and rebound. That's before we get into stuff like the LSD. I barely know how a differential even works. All I know for the suspension is that there's a bug with the ride height, where you get a higher top speed if you raise the front and lower the rear. Otherwise, I don't know if there's any real reason to do anything else with the ride height.

The only thing I think I'm decent at is tuning the gear ratio, where I think you want to tune the gears insofar you'd want it to be reaching the end of the rev range on a given section of track before you start braking, right? I also am not sure what's the difference between changing the top speed and the final gear ratio - they seem to have an identical effect of affecting all the gears' ratios. I think downforce is something I could tune for, too, especially given a track's layout (e.g. how much of the track is straight or uses high-speed corners), but even then, I'm not sure how to tune the downforce settings separately, like if I'd want the front or rear to have more or less downforce than the other. Would I, perhaps, want more front downforce in an FF car, like the Megane Gr.4?

Going back to that 330 P4 tune I saw, I also saw each pair of wheels had some camber. I thought you'd want zero camber for better acceleration, because more of the tire would be in contact with the road.

Is there a go-to guide or something, here? I feel hopelessly lost and that my best bet is to just copy other people's tunes. It feels like you need to already know how tuning works IRL to know how it works in Gran Turismo, whereas you should be able to learn everything in GT and then apply it to reality. This on-boarding is terrible, no wonder racing games are niche.

 

[JayRS200]

You're better reading all the details about tuning elsewhere. Even then because it's a game some things work differently to real life.

Also PD keep changing the physics and can't seem to settle on what "real" in "Real Driving Simulator" is. Although they seemed to have settled on horrific understeer as real. So you could get a good tune now that might not work when they change the physics again.

 

[dudejo]

I haven't played Gran Turismo in a long time but I do have some personal observations for optimizing gear ratios.

Let's say you have a 6000 RPM engine. Your first gear is 3:1 and your second gear is 2:1. When you shift from first to second, your 6000 RPM will drop to 4000 RPM at the same vehicle speed. In this case, it works out fine because the engine makes optimal power between 4000 and 6000 RPM (aka a powerband of 2000 RPM).

Now let's say your engine is swapped with a 12000 RPM unit. The RPM drop from shifting, just like the increased engine RPM, is scaled by a factor of 2. So now, shifting gears drops your speed down to 8000 RPM. In this case, this is bad because your engine makes optimal power between 10000 and 12000 (so still a powerband of 2000 RPM). You're suddenly losing performance.

One way to correct this is to set the second gear to a 2.5 : 1 ratio, which will keep the RPM drop within the powerband. Of course, this also means your top speed will drop. You can compensate for that with a taller final drive but then your first gear will perform differently as well.

 

[mirial]

I feel like the in-game descriptions in GTS are cryptic trash that doesn't tell me enough about how each setting works. For example, for the anti-roll bars. I saw someone's tune for the 330 P4 for the latest time trial, and it has the anti-roll bars set to ten on each end. I don't understand why, because I would've thought you'd want to tune the anti-roll bars to prevent oversteer, which is something I'd imagine the 330 P4 would be vulnerable to given its engine layout..

In general, setting the roll bars to 10 at both ends or close to that, will give good chassis response, yet will create just enough weight transfer to get the tyres to bite but without exceeding the limit of grip in the fast corners. You need to have the corresponding ride height as well otherwise 1-2 mm too high and the tyres will exceed their limit of grip once very heavy cornering takes place. Too low, and there won't be enough vertical load on the outside tyres to generate enough initial stiction before heavy cornering takes place.

Increasing camber also increases stiction before heavy cornering takes place because you are exerting a given load over less surface area, so the tyres are initially pressed harder into the tarmac. The downside of that is that you potentially have less rubber in contact with the road once full chassis roll develops, which might not be able to support the extra load on the outside tyres (the nature of rubber compresses in a non-linear fashion, resulting in it no longer being able to interlock deeper into the tarmac.) I haven't mentioned tyre distortion, and weight transfer causes a good amount of tyre distortion in GTS which can be used to good effect to counter the horrendous understeer with stock settings.

I have no idea how to tune the suspension, or even what various settings do like the compression and rebound. That's before we get into stuff like the LSD. I barely know how a differential even works. All I know for the suspension is that there's a bug with the ride height, where you get a higher top speed if you raise the front and lower the rear. Otherwise, I don't know if there's any real reason to do anything else with the ride height...

Compression and rebound can be used very effectively to both control the speed the chassis rolls and the extra weight transfer that is delivered with more compression and rebound. You generally want the chassis to roll as slowly as possible so that maximum weight transfer is delayed as much as possible, which is very helpful with a circuit that has lots of long corners. Stock damper settings should be sufficient, although the rebound tends to give the best compromise of allowing the chassis to roll slowly whilst minimising weight transfer.

Springs are probably best kept to the lowest settings with anything less than Gr.2, because those cars tend to be limited by mid corner grip (they tend to behave like pre-load before cornering takes place, so your car will exert too much weight transfer too soon on the front end. With cars that have a lot of inherent mechanical grip and downforce, increasing the weight of front springs can be used to press the front tyres harder into the tarmac on corner entry. Those cars have so much grip, that grip can be increased to your advantage.

As for the LSD, increasing it for initial will reduce the amount of rotation when off the throttle. Most expert drivers set this between 5-10 for best rotation on corner entry, but the car may be harder to drive in corners like T1-T2 at Suzuka.

Acceleration can be kept at 30. With the high grip cars, it can be set much higher (maybe 50) with a really good setup. There is a tendency for the inside wheel to spin on hairpins, but there is no danger of the differential slipping like a clutch either. Delivering more torque to the outside rear wheel tends to help steering with the throttle in medium speed corners. Keeping the number low, say around 10, will increase traction in slow corners but may slip like a clutch if the grip is high. That's why it's important to ensure the setup has good traction without breaking loose so that this can be kept as high as possible.

Going back to that 330 P4 tune I saw, I also saw each pair of wheels had some camber. I thought you'd want zero camber for better acceleration, because more of the tire would be in contact with the road.

In GTS, I've found you want some rear camber (1.5-2.5) so that the tyres initially bite (stiction) before they get loaded up on full acceleration. It's trying to get that balance between establishing initial stiction with the tyres pressing deeply into the tarmac surface and yet having just enough contact so that the outside tyre will accept the extra loading/torque being applied at that given moment. Whilst more camber will increase rear end grip on corner entry, it may reduce grip once the tyre is fully loaded mid-corner and exit and can be used to balance the high grip cars in GTS much better because they have so much understeer with stock settings.

With enough experience, you can feel what the tyres are doing which makes it easier to decide what tyres need to be more loaded/unloaded using ride-height/roll bars/springs/dampers and what tyres need their contact patches increased/decreased.