How to Calculate Rear End Gear Ratio

Rear end gear ratio is an important factor in determining the performance and efficiency of any vehicle. It refers to the ratio between the number of teeth on the input shaft (front wheel) and the output shaft (rear axle). This ratio determines how much torque is transferred from the front wheels to the rear wheels, which ultimately affects acceleration, braking, and overall handling.

To calculate the rear end gear ratio, you need to know two pieces of information:

1. The number of teeth on the front wheel drive sprocket (input shaft)
2. The number of teeth on the rear axle differential gears (output shaft)

The formula for calculating the rear end gear ratio is as follows:

Rear end gear ratio = Number of teeth on output shaft / Number of teeth on input shaft

For example, if your car has 36 teeth on its front wheel drive sprocket and 48 teeth on its rear axle differential gears, then your rear end gear ratio would be:

Rear end gear ratio = 48 / 36 ≈ 1.33

This means that for every one tooth on the input shaft, there are approximately 1.33 teeth on the output shaft.

It’s worth noting that this calculation assumes that all gears are perfectly meshed and that there are no slippage or other factors affecting the transmission of power. In reality, many vehicles have more complex gearboxes with multiple stages of gearing, which can affect the final ratio. Additionally, some modern transmissions use electronic controls to adjust the gear ratios based on driving conditions, further complicating the calculation.

When designing a new transmission system, engineers must carefully consider the desired rear end gear ratio to achieve optimal performance and efficiency. They may choose different numbers of teeth on the input and output shafts depending on the specific application, such as sporty cars, off-road vehicles, or commercial trucks.

In conclusion, understanding and calculating the rear end gear ratio is crucial for anyone involved in automotive engineering or design. By knowing the exact numbers of teeth on both shafts, designers can ensure that their transmission systems provide the best possible performance and handling characteristics for their intended applications.