Alright, here we go. Let's start by punching in the specs for our RM ZR1 into Quick Tune. In this case we have 905 HP, 830 lb-ft, and 1100 kg. Our recommended transmission ratios are now:
3.194
2.172
1.618
1.255
1.000
0.816
Let's pop into the transmission screen and check out the defaults.
Now, in this case we've lucked out in that we can plug in the Quick Tune gears right away as they all fall within the current adjustment ranges. However, for the sake of demonstration I will show you what to do in the more likely scenario that they don't fit. My preferred technique is to get both FIRST GEAR and the SECOND TO LAST GEAR in the same ballpark as the suggested QT gears. Here we can see that 5th gear is already very close to 1.000, but if it weren't you would simply adjust the top speed until it is. After that's done, compare both 1st gears. Here we can see that 1st is currently too short (numerically too high), which means we need to tighten the spread. To correct this we will progressively lower (numerically raise) the final drive, lower the top speed to reset 5th to roughly 1.000, then recheck 1st gear (If 1st is too tall you would reverse the process i.e. numerically lower the final and raise the top speed). Try pushing the final up to 3.800 and lowering the top speed to 199. You will see 1st is now 3.379, which is closer to our goal of 3.194. Repeat this process until you get something like this:
Now, you don't have to be anywhere as accurate as this, usually if your 1st is within 0.200 of the QT 1st you'll be fine, this is just for demonstration. At this point plugging in our QT gears is a piece of cake as the values are now very close.
Boom, there we go. At this point we have no idea what we want our final gear to be, so what we do is make an educated guess and take it for a spin on SSR7. In this case I'll guess 3.300. Make sure your aerodynamics are where you want them before proceeding. Since this is a circuit setup I have mine maxed out (35/60).
Oops, too short. The car is redlining in 6th and still pulling. Let's try 3.000.
Much better, it's no longer over-revving, but it's still not quite optimal. Let's try to get that tach needle right up smack against the redline.
That's more like it. After a couple more test drives I end up with a
3.100 final. This is as optimized as is humanly possible, in my opinion. Some caveats, however:
A) Obviously, if you plan on drafting you may have to raise the final.
B) Some cars fall flat on their face way before redline (R33 GT-R LM Road Car, Cuda 440, etc.). If top speed is a concern at all you will have to run a taller final to keep the car in the powerband.
C) If you're working on a top-speed-only tune you might want the car to max out near the RPM which coincides with peak HP rather than redline.
Finally, once in a while you'll come across a car where no amount of jockying will get the gears to fit. This is especially common in extremely slow K-cars and the type. This is where the Scale and Spread functions come into play. If you run into this problem and can't figure it out I'll try to talk you through it.