First, welcome to GTPlanet!
Gran Turismo is not a game, it's a way of life - you'll notice that you're thinking about some small settings changes when doing something completely different. You have been warned...
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Just kidding, enjoy the game!
I assume you're talking about the gear ratios. They decide the acceleration and top speed on each gear, and are a valuable thing when trying to get everything out of a car.
In a fully customizable gearbox every gear ratio can be adjusted individually. you can use this to your advantage for example in such situstions where the gearing is otherwise OK but the 3rd gear redlines before a corner and the 4th gear is too big for that corner. The solution: make the 3rd gear a bit longer.
Long gear ratios (smaller numbers) increase the top speed but decrease the acceleration. They can also be used to battle wheelspin on higher-powered cars.
Short gear ratios (bigger numbers) decrease the top speed but increase the acceleration. Use them on twisty tracks where the top speed doesn't matter so much.
The Final ratio is literally the final ratio between the gearbox and the driving wheels. The same rules apply on it as on the individual gears.
The gearing is often adapted to different tracks by just changing the final ratio as it doesn't affect the relative values of the individual gears.
The Auto setting is a quick way to make a rough tuning for a track, bigger numbers meaning longer gears here. You can then further fine tune the gears.
Never change the auto setting after fine tuning as it will reset the changes you've made.
In short, set the
Auto setting first, then make the
individual gears and then set the
Final ratio. When going to a twisty track, make the final gear shorter and adjust individual gears if needed. When going to a fast track, make the final ratio longer and adjust individual gears if needed.
Hope this helps,
- R -