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Gear section
Use this Gear calculator excel file (3kb), this file is a modification from NoQuarter excel file (you can get it from link at the bottom).
If you spend enough time with gear tuning, you can achieve a faster laptime. This is some example on how to tune the gear.
Shelby GT350
Enter the data to calculate the wheel diameter
Then enter the estimated wheel diameter, I shift at 7600 and use 2.500 final drive.
Enter the 1st gear ratio with any value to get ratio for the top speed you want, then use it to calculate the other gear.
In this example I want 150mph. The speed shows 150 when I enter the 1st gear ratio with 1.4. So, I use 1.4 as the 5th gear ratio. I want to use decreasing rpm drop so I leave the delta as it is.
If you want to use the same rpm drop after shift you can enter 0 on delta.
But as the value for 4th gear is outside the range, we have to calculate again with goal seek using 4th gear as value.
My opinion
- Lower final drive have the same effect as lighter flywheel. Use it wisely.
- Short gear have fastest acceleration.
- Car with flat hp figure can use wider rpm range.
Other excel gear calculator
Easy formula to calculate gear
I currently trying to convert all of my excell formula to my cellphone using sheet.jar. But it seems this application do not support fractional calculation (or maybe it can but I don't know how). And then I remember than all I need to carry is not all formula but only gear speed conversion unit. So I derive the calculation and found this:
new gear ratio * new final drive * new top speed = old gear ratio * old final drive * old top speed
This is acceptable on sheet.jar so now I don't need to open the excel file just to calculate new gear ratio  .
You can use this formula to calculate what you need to gain another speed.
As I don't remember my gear I use wheres the mini gear setting:
5th gear = 0.602
final = 3.100
top speed = 302mph
goal top speed = 315mph
using the same 5th gear ratio = 0.602
new final drive = old gear ratio * old final drive * old top speed / new gear ratio / new top speed
= 0.602 * 3.100 * 302 / 0.602 / 315
= 2.972
so the final drive need to be set at 2.972 to reach 315mph
Lycanthor gear setting
5th gear = 0.811
final = 3.100
top speed = 297mph
goal top speed = 302mph
using the same 5th gear ratio = 0.811
new final drive = old gear ratio * old final drive * old top speed / new gear ratio / new top speed
= 0.811 * 3.100 * 297 / 0.811 / 302
= 3.048
so the final drive need to be set at 3.048 to reach 302mph
sheet.jar, free excel for J2ME compatible phone by Siemens AG.
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