Hey guys,

Newbie Question, I don't quite understand the gear ratio equation. Like what does it mean when someone says the gear ratio of 1st is 12.08:1 or the final gear ratio is X.X:X?

Thanks,

input rpm / output rpm == gear ratio.

The final drive is yet another reduction after the shift gears and works the same way. Basically a gear ratio > 1 adds trque but reduces speed.

you have individual gear ratio's, which are something like 3.25 for first, 2.05 for 2nd, etc, and then you have a final drive, say, like 4.063

the individual gears determine how close ratio your trans is, as in, how many RPM's you drop from the first to second shift, and second to third. One other note on individual gears, a gear that is lower than 1, like a .73th 5th gear, is called an overdriven gear (you know, the term overdrive, that's what that means).

to get your overall ratio like the 12.xx you mention, that's when you take an individual gear and multiply it by the final drive. it basically means that at 12.xx overall gear, your engine will spin 12.xx more than the trans? Someone will tell you better this part

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96 Saturn SL2 Turbo (evil SL2)

My cardomain site: cardomain.com/memberpage/702872
T3 60 trim + 4 PSI + crappy tires = 14.47 @ 99 MPH and 31 MPG

god damn if 1st gear is 12.08, i dont think the car is going anywhere, thats basically taking whatever the engine's torque is and multiplying it by 12 at the driveshaft/transaxle (FR cars have an axle ratio too, that typically further changes it). the higher numerically the gear ratio is, the shorter the gear. as stated before, shorter gears give more acceleration at the expense of top speed. thats why first is typically really short (usually 4.something), then 2nd is a little longer (mid-high 2's, low 3's depending on transmission), 3rd ranges anywhere from low 3's to high 1's, 4th is sometimes overdriven, if not then its low 1's, and then 5th and 6th are overdriven, like 0.86 and 0.54, respectively. this is good for gas mileage, as you can go at a high speed while maintaining low engine rpms.