Higher, lower, taller, shorter, more, less…how do you have any idea what guys are talking about when it comes to rear-axle gears? It’s confusing, because the slang seems to contradict the math.
Let’s start by explaining the function of the ring-and-pinion gears in your axle. First, they change the direction of the power by 90 degrees, taking rotational force from the engine/trans/driveshaft (inline with the car’s centerline) and sending it out to the axles and the wheels (perpendicular to the car’s centerline). Second, the gears provide a mechanical advantage, acting like a lever to multiply work (torque).
Parasitic losses aside, a 3.0:1 ratio multiplies torque three times and a 4.0:1 ratio multiplies it by four. Go to our example of a simple lever (right), and you’ll see that, any time…