I’ve wondered this for a while. What do they mean?
yeah I’ve wondered about this for a while, tried to understand it but i just dont get it.
Andy
The best example that I can give is this. You have one gear that has ten teeth, and another gear that has five teeth. This gives you a factor of x=10/5. Through simplification this gives you 2/1 or essentially 2:1. Application of this in a transmission would be to the gears on the mainshaft and countershaft I do believe. Dan?
Jetspd is right. They are a ratio of the revs on the input shaft to the output shaft of the tranny. If the number is for instance 3.5 then the revs on the output shaft is the engine revs divided by 3.5. So if your revving at 4000 rpm and your total drive ratio (including transmission and axle gears) is 4.0 then your axles and wheels would be rotating at 1000 rpm. BTW you multiply your tranny ratio by the axle ratio to get final drive ratio.
Rick
Putting it in simpler terms, it is the circumference or the number of teeth of the driven gear divided by the same on the driving gear. This number also equals the number of times the driving gear has to turn to move the driven gear one revolution. Final drive ratio is the same way, only there is a driving gear coming from the tranny driving the gear on the differential. As 93Teg44444 said, these ratios are multiplied together to find the total gear ratio.
thanks for clearing that up
ARCHIVETHIS
You can also roughly calculate vehicle speeds at different rpms and different gears if you know the circumference of the tires you’re using. Another handy thing is that you can take the different gear ratios and compare them and then see roughly what the rpm drops will be between shifts. I believe SCC did a whole article on gear ratios not too long ago, I’ll see if I can dig up the article sometime, it did a good job of explaining everything.