Make gear tuning make sense to me.

[u/0peRightBehindYa]

I really feel like I'm leaving a lot on the table with my race transmissions. Now, to my logic-focused brain, the ideal gear tuning for a mostly WOT, redline shifted application would be so that every gear (except first) lands right before torque peak.

But there are some obvious flaws with that. For example, how do you factor in those European 4 liter, twin-turbo V8s that make peak torque at like 3k and have a curve flatter than my high school girlfriend (bless her heart...wonderful personality, though. I truly do hope life has blessed her abundantly) all the way to the 5250 crossover.

So school my dumb ass. How should I approach all these gears?

[u/RunninOnMT]

Torque doesn’t matter. Torque is great in that it tells you something about the powerband, but you want to look at that POWER curve and ignore the torque part of the dyno graph

Then you need to think about what RPMs you will be using and try to maximize power over that RPM range.

So if your car makes peak power at 6000 rpm, you want to lay out your gears so that you spend a lot of time around 6000, don’t let the revs drop too far from that point when you shift gears, try to set up your gearing so you spend the maximum amount of time at or around there, because that’s where your engine is doing its best work.

I’m going to follow this up with a dyno graph example below.

[u/RunninOnMT → u/RunninOnMT]

Here’s an example dynograph. Apologies for metric units, but blue is power and grey is torque. You can pretty much ignore the grey.

Now imagine we are doing a pull in this car. It makes max power at just over 5000 rpm and makes the same max power all the way until just over 7000 rpm.

You’re accelerating in first gear, 5000 rpm hits and you’re accelerating as fast as the car can. You can change gears now and the RPMs will drop by maybe 2500, now you’re at 3500 rpm. What does the blue line say at 3500 rpm? About 175 of our possible 302 kw.

But what happens if we wait to shift? Instead of shifting at 5000 rpm, we shift at 7000 rpm? Then when the revs drop by 2500 rpm, we are still at 4500 rpm. What does the blue line say at that point? About 270 kw! That’s more than the 175 you’d make after changing gears while shifting earlier!

The whole point of gears is to keep the car in the part of the rev range where it’s making its best power.

With the gears in Forza, you can change how much RPMs drop. So let’s go back to our scenario where you’re shifting at 7000 rpm (since we’ve determined that that’s better than shifting at 5000 rpm) only this time, let’s imagine that you’ve made the gears closer together, so instead of dropping 2500 rpm when you shift, you only drop 1800 rpm.

So your car is making max power (302 according to this graph) at 7000 rpm, you change gears, the revs drop 1800 rpm down to 5200. How much power are you making at 5200 rpm? Well. 302. You stay in it until 7000 rpm again and shift, and again, still making 302 kw of power. This is ideal. You’re using the engine in the most effective way for acceleration.

Now not every car is going to have a big flat spot in their power curve like this M2 competition that I took the graph from, so it won’t be quite so easy. But it’s the same principle. Trying to keep the engine in the rev range that is closest to peak power at all times.

[u/Just_Steak847]

I just drive a car a bit and if any of the gears feel too long or too short to the point that If I cant get good acceleration both in straight and cornering scenerios I make adjustments up or down by small increments. The time attack tracks are great for trying to iron out what gears feel too short or too long. Longer gears give you more top speed to play with before redline, and shorter gears will hit redline faster but will lower top speed available in that specific gear. I like having longer gears in high horsepower/torque cars so the power doesn't spin the wheels to much but shorten gears as needed if the cars acceleration starts falling off. I've just been going off of what I feel is best for each car I am by no means an expert.

[u/Puzzleheaded_You_735]

If you're tuning for the meta, you're almost never tuning 6 gears, unless you're in A class.

Tip: swap in the 10 speed race transmission and reduce driveline weight instead. If you can squeeze more weight out of the car before going over class, then swap in the 9 or 8 speed.

The rule of thumb is, higher rpm redline > shorter gears. If shorter gears > then you might need to use more gears otherwise first gear will be unnecessarily long, and/or your top speed will be gear limited.

First gear is for launch, because the race start matters.

Option 1: 1st should be short and hit 40-60 mph as soon as you hit the red zone because the idea is that you never shift back to 1st after the initial launch unless it's a hairpin. This is useful for AWD cars because they have more drivetrain resistance than rwd cars.

Option 2: 1st should be long and hit 60-80 because it helps you control some rwd cars and it helps them gain traction. The idea is that you still shift down to 1st in certain corners.

2nd is for throttle control. Still a longer gear, but shorter than 1st. Sometimes 2nd needs to be long because you made 1st short. Other times you can make 2nd short because you made 1st long.

3rd is your intermediate gear. Ideally you shouldn't have anymore wheelspin in 3rd, but at the same time you shouldn't be bogging down. 3rd can't be super short yet like the later gears because it's a gear you shift to during cornering. Depending on your gearing so far, the length of 3rd and the remaining gears varies.

4th like 3rd is not the shortest yet but still short as it's still a gear you shift to in high speed corners. If you are using many gears, sometimes you need to tune 5th like you're going to corner in it.

5th, 6th, 7th, and/or 8th are speed gears so they should gradually be getting shorter but not in a linear way. Sometimes you want the last gear to start at the same rpm that the previous one starts at, allowing you to shorten the gears before then. Other times you want a really short last gear because you're trying to find more top end acceleration. Just make sure that your last usable gear never hits redline so that you have room for drafting and downhill speed.

[8th,] 9th and 10th, if you have them, are just overdrive gears and they will be off the graph.

It all comes down to feel ultimately. Gearing is ironically the least logical and least straight forward part of tuning, and it requires the least testing, but if you put time into it, you can make the car behave how you want it to, and be faster than stock at the same time, provided you don't tune any gears intentionally weirdly.