Ratio to Ratio

You’ll have to bear with me here as I try to figure something out about gearing. I wanted to redo all of my gear ratios, but it has turned into a mathematical and theoretical nightmare. Anything over a 1:1 ratio at the gearbox is said to negatively impact acceleration, and a closer ratio at the diff is said to also impact acceleration negatively. The problem is you can’t really have one without the other. For example if I were to use a 1700kg, 540hp, 322km/h car and make 5th gear 1:1 the final ratio would have to be 3.225:1. So suppose you consider that that differential ratio is too small, and will hurt acceleration, so you make 4th gear 1:1, now 5th gear will be about 0.785:1 and the diff. will be 4.150:1. So if you use that 4.1:1 diff. now 5th gear becomes an over gear, which is also supposed to negatively affect acceleration. Put the cars on a track and there is no difference what so ever in times. Which brings up the question, why does it matter? I honestly don’t know, just me striving for realism I suppose. What I’m doing is taking each car with the gearing I had previously made for it and running it to the rev limiter and then recording what speeds it reaches in those gears. With this information, and knowing the ratio I can use math to figure out the new settings I want. This number is only approximate, but it takes a lot of the guess work out of re-gearing. I built the equations up in excel so I only had to enter in numbers to get the approximate results. Yet now I'm trying to figure out if it is really worth it.

Here's kind of an example of how it works:


This is handy, but it still has not solved my problem. Why do manufactures use a 1:1 gear ratio anyway? I will probably only use this for new gear ratios and not change any more of the older ones.