Kev,
First up I'm glad you like the car. It's always nice to hear that there is someone else out there enjoying one of my builds
It's good to see you running it without TCS too. I never run with it either, which might be why you got on with this tune so well - you don't need the TCS to stop it spearing off into the nearest Armco. I ought to also point out that the baseline tune is achieved through Feuerdog's v.5 calculator - all I've done is tweak it a bit to suit my driving.
As for the gear ratios, I'll giude you through my procedure (which is a lot less technical than Blooze's transmission spreadsheet). It should also explain how I came to have the FD set to such a low figure. With this car I usually shift up a gear about 500rpm below the red line as the engine tends to die as you get close.
First job is to set the final drive. This one is set by feel - I adjust it until first gear gives me the best possible launch. I usually aim for a launch where I get minimal wheelspin (or at least where I get controllable wheelspin) without the engine bogging down. With the high levels of power and low levels of grip on the Trans Am I ended up with a very long first gear. As that was achieved through adjusting the Final Drive, I had a very low figure for this.
Second step involves noting the rpm at which the engine develops maximum power. For simplicity, I'm going to say that the engine in this example has the maximum bhp at 6000rpm.
Next step is to run the lap you want to set the gears for with the final drive now set. You should now aim to see how many rpm you're pulling at the fastest point on the track. (With a car like this, there is enough torque that you probably won't have to use all the gears - if you have a car which bogs down between gears you should aim to use all 6 (or at least more than you're using in this test)). For this example, we're going to assume that you reach 5000rpm - there's no need to be any more accurate than to the nearest 100 rpm - in 5th gear (which has a gear ratio of 1.00) at the end of the longest straight. As the car doesn't seem to be bogging down between gears, we're going to build us a 5-speed car.
This is the stage where some simple maths comes in. We now adjust 5th gear to match the figure given by this equation:
New ratio = Existing ratio x (rpm of peak power output/rpm at end of longest straight).
Using the figures in this example, our new 5th gear ratio is:
1.00 x (6000/5000) = 1.20
I usually then just adjust the intervening gear ratios by eye to give a nice smooth curve which, although it doesn't optimise the raios, does give you a good set of gears.
The final step is minor tweaking. If you've made a big change to your top gear (as here), you may find that the car is hitting a higher speed (and hence higher rpm) at the end of the straight, and so you may want to repeat this process. You may also find that some of those intervening gear rations fall awkwardly in the middle of a corner, and so you'll want to adjust those to avoid that if you can. Just don't make things worse in another corner
Finally, as you like it most on Silverstone National, I'll put up my ratios for that track later tonight when I'm next on. I can't remember exactly, but I expect they won't be hugely different to the ratios for Sunset.
EDIT: The Silverstone ratios are:
FD: 2.35
1: 2.89
2: 2.17
3: 1.73
4: 1.42
5: 1.21
6: 1.09
If my memory serve me correctly, this one is a 4-speed setup
