1. What is Final Drive Ratio?

The final drive ratio is the gear reduction in a vehicle's drivetrain that converts the rotational speed of the transmission to the rotational speed of the drive wheels. It's calculated by dividing the number of teeth on the ring gear by the number of teeth on the pinion gear.

2. How Does the Calculator Work?

The calculator uses the simple formula:

Where:

• Ring Teeth — Number of teeth on the ring gear
• Pinion Teeth — Number of teeth on the pinion gear

Explanation: The ratio represents how many times the driveshaft must rotate to turn the wheels once.

3. Importance of Final Drive Ratio

Details: The final drive ratio affects a vehicle's acceleration, top speed, fuel economy, and towing capacity. Lower ratios provide better fuel economy at highway speeds, while higher ratios improve acceleration and towing power.

4. Using the Calculator

Tips: Enter the number of teeth on both the ring gear and pinion gear. Both values must be positive integers (typically between 10-50 teeth for most vehicles).

5. Frequently Asked Questions (FAQ)

Q1: What's a typical final drive ratio?
A: Passenger cars typically range from 2.5:1 to 4.5:1, while trucks might have ratios from 3.5:1 to 6.5:1.

Q2: How does ratio affect performance?
A: Higher ratios (numerically larger) improve acceleration but reduce top speed. Lower ratios improve fuel economy at highway speeds.

Q3: Can I change my vehicle's final drive ratio?
A: Yes, by replacing the ring and pinion gears, but this requires specialized tools and knowledge.

Q4: What's the relationship to RPM?
A: Higher ratios mean higher engine RPM at any given speed, while lower ratios mean lower RPM.

Q5: How does this relate to tire size?
A: Larger tires effectively lower the final drive ratio, while smaller tires effectively increase it.