I worked out a quick way of getting the top gear mostly correct is to.
I completely stopped using race transmissions, i only use sport transmission. Because the race transmission sounds horrible.
Even Rammstein can’t block them out for you?
You mean the real race transmission sound?
It should work with Sport gearbox also.
You are making a critical error if you are putting the final gear lower than the achievable top speed. Most tracks, there is not enough room to even gain the stop speed on most vehicles so this does not matter, but on tracks such as LeMans, Daytona, Road America, and even on Spa’s/Hakone’s straight it does. Drafting is very useful in this game and you can gain up to 10 MPH or more by doing so on long straights. Because of this, you need to leave room for the gearing to reach those speeds. For most of my speed tunes, I have it set to 10 mph or a little over for this reason. I wish they would implement the power band graph every Forza had prior to this installment, so that tuning would be easiery and quicker, but that discussion is for another day.
I usually run mine with a very tall 1st and 2nd, with 3rd-6th (or higher depending on car) all stacked up on each other, with final drive set to about 5mph higher than solo achievable speed on the longest straight for the track (to account for slip stream, and not bounce off the rev limiter). My thinking is that on any race track a) I should only need 1st gear once and b) if I do have to use the lower two gears the longer ratios will help with traction.
My general ratios are
1st: 2.60
2nd- 1.70
3rd- 1.40
4th- 1.22
5th- 1.09
6th- 1.0
I have refined this to be better.
Class, drop in MPH from top speed ratio
r=2.4mph
s=2.2mph
a=2.0mph
b=1.8mph
c=1.6mph
d=1.4mph
e=1.2mph