Maybe someone can shed some light on the subject here. Somewhat of a Noob when it comes to car still so.

Something that has perplexed me for the longest time is gear ratios. The ratio from trans to output shaft to rear end and how all that converts into real world.

when you have a 3.73 gear. does that mean that the transmission output shaft is spinning 3.73 times?

and final gear.... I really don't get how that works. is that talking about the gear ratio in the transmisson to the gear in the rear end to make the final ratio...?

I don't know maybe I'm just not thinking hard enough. I need a good site that will explain it to me. or maybe someone that will explain it properly.

from engine to transmission I understand. anything beyond that is alien to me.

 

I might of found my answer.

http://auto.howstuffworks.com/transmission1.htm



by the way I drive a 89' GTA with 700r 4 spd /od. 5.7L98 no mods except injectors.

the car's top speed is close to 120mph. the needle almost reaches it. roughly 190kph.

I'm almost positive the previous owner changed the rear end. the axle in the back still looks mint compared to the rest of the car. what gears do you think she's running?

 

i believe it works like this. the first gear on the 700r4 is 3.06. this means that for every one time the engine spins the 1st gear spins about 3 times. for the rear end, if you have 3.73 gears, for every time the driveshaft spins, the wheels spins roughly 3.7 times faster.

maybe someone with more knowledge can shed more light.

 

Demon you have the rear backwards. The tranny ratio is crankshaft/driveshaft, and the rear end ratio is driveshaft/axle. The "final drive ratio" is trans gear multiplied by rear gear, which give you a crank/axle gear ratio.

First gear in my T-56 is 2.66:1. For every 2.66 turns of the crankshaft, the driveshaft will turn over once. I have 3.70 gears in the rearend, so for every 3.7 turns of the driveshaft, the axles (and therefore the wheels) will turn over once. The final drive in first gear is 9.84 (2.66 x 3.70) which means that in first gear, the wheels rotate once for every 9.84 rotations of the crankshaft.

In second, the final drive is 6.59 (1.78 trans ratio for 2nd gear,) so for the wheels to rotate once it only takes 6.59 crank rotations. This means fewer crank rotations for the same number of wheel rotations, which means fewer RPM for the same speed (or higher speed for the same RPM.)



Turismo's link is a more in-depth look at this information.

 

thanks J

it still took me a while. but help with the calc and some hard thinking and I got. thanks a lot man.

 

nice, now i kinda understand how gears work!!!