Why a shorter rear gear will accelerate the car quicker
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For the same crankshaft speed, the taller gear (2.73:1) will allow the car to go faster, but not get there as quickly. The shorter gear (3.73:1) will allow a slower top speed, but will get there in a hurry. | For the same crankshaft speed, the taller gear (2.73:1) will allow the car to go faster, but not get there as quickly. The shorter gear (3.73:1) will allow a slower top speed, but will get there in a hurry. | ||
| − | In addition to more power pulses, the numerically lower gear will multiply the torque in a direct ratio to the the amount of gear change. Take an engine that produces 400 ft/lbs torque with no gear reduction. With a 3.00 rear gear ratio, it will out put 3 times the torque at the wheel. If the same 400 ft/lb engine has 4.00 gears behind it, the torque will increase 4 times producing 1600 ft/lbs of torque. The downside is the reduction in wheel speed, now at 75% the original speed for the same engine rpm's. EXAMPLE: A motor turning 5,000 rpm's with a 3.00 gear and 88" circumference tire has a terminal speed of 138.88 mph. A motor turning 5,000 rpm's with a 4.00 gear and 88" circumference tire has a terminal speed of 104.16 mph, a reduction of 25%. | + | In addition to more power pulses, the numerically lower gear will multiply the torque in a direct ratio to the the amount of gear change. Take an engine that produces 400 ft/lbs torque with no gear reduction. With a 3.00 rear gear ratio, it will out put 3 times the torque at the wheel. If the same 400 ft/lb engine has 4.00 gears behind it, the torque will increase 4 times producing 1600 ft/lbs of torque. The downside is the reduction in wheel speed, now at 75% the original speed for the same engine rpm's. EXAMPLE: A motor turning 5,000 rpm's with a 3.00 gear and 88" circumference tire has a terminal speed of 138.88 mph. A motor turning 5,000 rpm's with a 4.00 gear and 88" circumference tire has a terminal speed of 104.16 mph, a reduction in terminal speed of 25%. |
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