Hello all,

was wondering if a kind cyber-grease monkey could describe the process he/she uses to setup gearing? If the Gear Ratio Calculator is utilised, all the better. Thanks in advance

If you're trying to create a setup from scratch, the GRC is generally a good start if you know the top speed of the car at the track you're dealing with.

Here are some steps I've found useful.

1. Do a few practice starts in single-player mode. If the wheels spin too much, reduce the ratio on the first gear. If the engine bogs when you try to launch, increase the ratio.
2. Set top gear such that when at top speed, you're slightly past peak power. 500 RPM past peak power should be the limit. 250 RPM is probably better for most cars.
3. Use the GRC to evenly space the gears in between and copy the values into your set.
4. Drive around on the track. When coming out of a corner, your revs should be somewhere between peak torque and peak power. If you find the revs are too low in a corner and downshifting makes the revs too high, change the ratio(s) as appropriate. It's okay for the lower gears to be spaced out more than the higher gears, so try increasing the ratio on the lower gear. You may want to incease all the higher gears a bit too so there is not too small of a gap between gears.

Part 4 largely involves trial and error to find ratios that work at a particular track. Also, tweaking ratios can be useful in limiting wheelspin out of a corner. Just reduce the ratio a little bit and you should find it much more managable.

Usually I'll just copy the gearing from the WR set if available. When making my own gearing I adjust it for the corners and straights. You should set highest gear to nearly reach the rev limiter on the longest straight where you reach top speed. The other gears should be setup so you're in the power band for the corner and not changing gears mid way through. Ideally shifting up or down before and after the corner. 1st and second depend on the car and if you're downshifting that low, but usually they're short and used to get a good take off.

Great advice guys thanks heaps however if I were starting from scratch, how does one determine the top straight line speed? Which of the ratio settings is best to tweak first?

Davo you mentioned copying WR set's gear ratios, I'd like to know what procedure they used to get those settings.

Quote from Herbz :

Great advice guys thanks heaps however if I were starting from scratch, how does one determine the top straight line speed? Which of the ratio settings is best to tweak first?

Well you need to do a few laps around the track first and you'll see what kind of speeds you're getting down the straight. Plug that speed plus a few extra km/h into GRC and you'll get your ratio. I usually tweak the highest gear first and then just work on them all at the same time after that noting the speeds in corners etc.

Quote :

Davo you mentioned copying WR set's gear ratios, I'd like to know what procedure they used to get those settings.

Well I imagine the way that we've described would be one of the ways they derive their settings. I don't think that there's too many ways to go about it, the ratios might differ slightly from person to person but not by much. Depends on what's comfortable sometimes.

I've been using this homebrew close-ratio gear setup for the 6-speed gearboxes with much satisfaction, which I hereby call the Provably-Optimal-Gear-Ratio-Set.


1st: 3.0-4.0
2nd: 2.0
3rd: 1.5
4th: 1.2
5th: 1.0
6th: 0.9
final drive ratio: variable

So, as mentioned by the others, adjust the final drive ratio so that you hit max velocity at around redline in top gear (e.g. 3.8 for FXR, 3.7 for XRR). Adjust the 1st gear according to the starting characteristics of the car (e.g. 4.0-5.0 for FXR, 4.0 for XRR).

We now prove the Provably-Optimal-Gear-Ratio-Set theorem.

Proof:
Observe that presented gear ratios between adjacent gears become progressively "tighter" as we move up through the gears. This is in accord to the relative decrease in torque multiplication as the gear number goes up. Hence, we have harnessed the power characteristics of the engine in such a way as to exploit the diminishing torque multiplication of the higher gears by decreasing the change in the gear ratio loads as we move up through the gears. It is easy to see that the Provably-Optimal-Gear-Ratio-Set presents a sequence of decreasing ratios-of-adjacent-ratios. That is,

1st/2nd: 3.0 / 2.0 = 1.66
2nd/3rd: 2.0 / 1.5 = 1.33
3rd/4th: 1.5 / 1.2 = 1.25
4th/5th: 1.2 / 1.0 = 1.2
5th/6th: 1.0 / 0.9 = 1.11

Hence, we have demonstrated our claim. QED

Thanks again guys, very helpful

Kernelpanic, thanks for providing the ratios and explanations etc, very much appreciated.

Quote from kernelpanic :

I've been using this homebrew close-ratio gear setup for the 6-speed gearboxes with much satisfaction, which I hereby call the Provably-Optimal-Gear-Ratio-Set.


1st: 3.0-4.0
2nd: 2.0
3rd: 1.5
4th: 1.2
5th: 1.0
6th: 0.9
final drive ratio: variable

So, as mentioned by the others, adjust the final drive ratio so that you hit max velocity at around redline in top gear (e.g. 3.8 for FXR, 3.7 for XRR). Adjust the 1st gear according to the starting characteristics of the car (e.g. 4.0-5.0 for FXR, 4.0 for XRR).

We now prove the Provably-Optimal-Gear-Ratio-Set theorem.

Proof:
Observe that presented gear ratios between adjacent gears become progressively "tighter" as we move up through the gears. This is in accord to the relative decrease in torque multiplication as the gear number goes up. Hence, we have harnessed the power characteristics of the engine in such a way as to exploit the diminishing torque multiplication of the higher gears by decreasing the change in the gear ratio loads as we move up through the gears. It is easy to see that the Provably-Optimal-Gear-Ratio-Set presents a sequence of decreasing ratios-of-adjacent-ratios. That is,

1st/2nd: 3.0 / 2.0 = 1.66
2nd/3rd: 2.0 / 1.5 = 1.33
3rd/4th: 1.5 / 1.2 = 1.25
4th/5th: 1.2 / 1.0 = 1.2
5th/6th: 1.0 / 0.9 = 1.11

Hence, we have demonstrated our claim. QED

stating the theory doesn't prove it (although i do tend to agree with the theory).

but going along these lines of thinking, wouldn't it be "more optimal" if the ratio of ratios of ratios came out to a constant?