IDing gear ratios formula

[Trip]

.....(and in a long shot, does anyone recognize my Cobra as a former board members ride, maybe I can get some more info about it) its a low miles 01 vert, my car had been modded a bit before I got it(check out the avatar pic.....BBS RKs, 42lb inj, Borla Phantoms, and from the looks of things even had a Vortech at one point that was removed before trade in)...so to move forward I am trying to identify everything I can, so I can make a plan for future mods and get a Dynotune.......and I have no idea if the gears have been changed sooooo does anyone have an exact formula for RPM to speed for each gear ratio, 327, 356, 373, 410 etc...or is there somewhere online that I can locate this.....thanks

 

[Trip]

And the car was owned in Duluth GA, suburb of ATL GA........

 

[3B99SVT]

Easiest way I know is to get both rear tires in the air. Put the tranny in neutral. Rotate one of the rear tires until the valve stem is on the bottom (or top). Put a chaulk mark on the driveshaft. Rotate the tire one full revolution while counting how many times the driveshaft spins. Depending where the chaulk mark ends up, you should be able to identify the gear ratio of the rear end. 3 1/4 turns = 3.27, 3 3/4 turns = 3.73, etc.

 

[Trip]

cant lift my car right now, but figured someone had a formula...tested it on the road and 5th gear @ 60 running 2150 rmps approx......stock 3.27 probably?

 

[na svt]

you have 4.10s.

Gear Ratio Calc

 

[Trip]

thanks....that explains why this NA vert pulls so friggin hard......I knew there had to be a calculator for this.......just discovered 42# injectors too......I wish I could talk to the Previous Owner so I could get the full list of mods....seems to have had pully replaced too....