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Discussion Starter #1
i was told when i bought my 02 gt it has 373s installed already, it doesnt feel to me like it does so i was wondering how do i tell? i have 17" deep dish bullits on the back with 315/35s on it if that affects anything..
 

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What you need to do is jack the back of your car up so both wheels are off the ground (use jackstands to hold it). Put the car in neutral and make a mark on your drive shaft. Now rotate a wheel 1 full turn and keep track of how many times the drive shaft turns. If the drive shaft turns about 3 and 3/4 times for 1 wheel turn, you have 3.73 gears. If it turns just over 4 turns, you have 4.10 gears.
 

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Discussion Starter #3
ok the tire size doesnt matter since there arent stock wheels? also what is the stock gear in these and how many rotations would that be? thanks
 

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Stock for a gt is 3.27, so about three and a quarter turns of your driveshaft. If you feel like taking the diff cover off, the ratio should be stamped on the pinion if you have ford gears
 

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Tire size won't matter for what gears you have. But tire size will matter for overall acceleration when driving.

I'm not 100% sure, but I believe stock gears are 3.27s. So that would be about 3 and 1/4 rotations.

*EDIT* Ninja'd
 

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Stock for a gt is 3.27, so about three and a quarter turns of your driveshaft. If you feel like taking the diff cover off, the ratio should be stamped on the pinion if you have ford gears
You don't have to take the diff cover off. Just jack up the rear, turn the tire, and watch the driveshaft.
 

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You don't have to take the diff cover off. Just jack up the rear, turn the tire, and watch the driveshaft.

I know man, I just put it out there so it might help somebody. Granted the tire method is quicker and cleaner but if someone wanted to double check they could pop the cover off as well. If they went that far and wanted to triple check they could count the number of teeth on the ring gear and divide that by the number of teeth on the pinion. Not trying to undermine anyone or anything, just trying to put more info on the table along with everyone else
 

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when i bought my 02 they told me it had gears, but they were'nt sure what ratio. i was convinced it had stock gears because it felt so tame. i got 4.10s put in and sure enough it had 3.73s. moral of the story, 3.73s feel really mild
 

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the way i figured mine out was, to just use a gps and judge by the rpm's.
there is a gear ration chart on the helpful links section and you can tell how many rpm's you should be at in fourth gear. 3.73's are about 1950 in fourth at 40mph i believe is what it was
 

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Discussion Starter #11
the way i figured mine out was, to just use a gps and judge by the rpm's.
there is a gear ration chart on the helpful links section and you can tell how many rpm's you should be at in fourth gear. 3.73's are about 1950 in fourth at 40mph i believe is what it was
since i dont have stock tires will that affect it?
 

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No, your 315/35-17 tires have exactly the same tire wall height (315 x .35 = 110) as the stock 245/45-17s ( 245 x .45 = 110) so they do not affect anything.

If your speedometer is correct (reset with a tuner) and if your tach is correct (which may not true if a gauge overlay has been installed) then in rough terms 40 mph is roughly 4000 rpms in second, 3000 rpms in third and 2000 rpms (actually 1950) in fourth with 3.73 gears.
 

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Discussion Starter #13
no gauge overlays, yet and supposedly the speedo was corrected with a tune but i have a gps to double check . the only other question i have is if my gps and speedo are a couple mph's different what would you go by??
 

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i would go by the gps, but if your car has gears it will be more than 1 or 2 mph difference in the speed. the tires make a little difference but no where near as much as gears do so that shouldnt make a difference in determining if you have gears.
 

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If you have 3.73 gears and the speedometer has not been corrected then the speedometer will read 14% higher than your actual speed at all speeds (3.73/3.27 = 1.14). If the actual speed is 30 mph, it will read 34 mph. If the actual speed is 80 mph, then it will read 91 mph.
 

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Discussion Starter #16 (Edited)
well my brother borrowed my gps so i didnt have it hear to verify my speedo is correct but i got roughly 1900 rpms in 4th at 40mph , third gear was way off i cant even remember the rpms that was at 40mph and 2nd at 40mph was about 3900 rpms. does this sound normal for stock?
 

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That's 3.73 gears.
 

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Discussion Starter #18
ok just checked again one more time and at exactly 40mph this is what i have: 2nd gear= 3800-3900 rpms, 3rd gear= 2500rpms and 4th gear 1800-1900 rpms
 

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Yes. Fourth gear at 40 mph is 1950 rpms with 3.73 gears. I just check. I didn't remember 3rd gear correctly. Here a link for more information:

PaladinMicro
 
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