Another thing to remember is that every engine 'likes' a particular rear gear. If you over- gear your engine, you end up with what Hazmat said. If you're crossing the line at the time when your engine is no longer making horsepower (torque X RPM/5252), you aren't gaining anything. Your ideal rear gear will allow you car to be in the power band when it crosses the line. Too long of a gear = not optimum... too short of a gear = not optimum. You want a good balance between.
Commercial trucks have 2 speed drive axles. Use it to split the transmissions gears for heavy loads. That's a lot of shifting. Regarding top speed, a lower gear, numerically, does not necessarily mean a faster car. You got to have the horsepower to pull a tall gear. Power needs go up drastically to go fast. 150 might get touched, but not for long!
the rearend gearing thing can be alittle overwelming, alot of roundy round racers well install quick change rearends for differant length tracks to stay in peak power powerband - rpm. Far as drag racing its all about traction ,to low gears usally ends up with smoking tires, to high of gears slower start with wasting time building rpm. What usally happens with new lower gears is need for bigger tires to get traction back. Many races lost by to much torque and not able to get traction. The combination of the the right gearing to HP getting traction makes a fast car
I know it's not possible..but imagine if folks figured out a way in which one could select what kinda rear axle ratio they wanted at the push of a button?
Just thinking out loud... : p
Closest you can get in a street car is a Gear Vendors Over/Underdrive. Basically a splitter gearbox, mounts to the rear of the trans, you make a custom driveshaft to fit back to the diff. Makes your 5 speed trans a ten speed. Of course, our trans doesnt have an application, cannot imagine the programming required. and they are pricey, at close to 3K a pop, not counting the few hundred for the driveshaft.
Come the day I get moving on the 68 Cougar, I hope to find the cash to strap one behind the C6 trans in that car.
"For a mechanic, you seem to do an excessive amount of thinking."
―C-3PO, to R2-D2
Last edited by GLHS837; 08-15-2013 at 11:24 AM.
Reason: For basic math:)
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