Shorter gears for 901 Options

[grantsfo]

My original 901 (never been rebuilt) tranny lost second gear. So I have found a loaner 901 transmission while I have mine rebuilt. I'm going to go for shorter gears. Can somone help educate me to options around shorter gears for a 901 transmission. I'm having a shop do the work but I want to educate myself to what track drivers think works best for gears. I have a 2.4 that makes something around 160 to 170 HP and use 265/45/16 tires in the rear. I will mostly be just having fun doing track days.

[brant]

grant,
it depends upon the track length and your powerband.

without going to a dyno

you would need to calculate your top speed at the longest straight and then calculate that to 5th gear.

then once you have a 5th gear picked out you work backwards from there to equalize the gaps between each respective lower gear.

of course aerodynamic drag plays into it and you can have bigger gaps between the lower gears than you should have between the top gears.

finally the next factor is cost. Some gear ratios cost 50 bucks and others cost 800$. So it becomes necessary that if a certain ratio is perfect but the next closest thing is 600 cheaper you might use the compromise ratio.

in the end.
people will tell you to go msx

but that doesn't mean it is actually the fastest option.
just simple. I found my car to be faster by using lower ratio's than msx

I will have those 3 ratios available for sale soon as used.
brant