1. What is Hub Ratio?

The Hub Ratio, also known as the portal gear reduction, is the ratio between the wheel RPM and driveshaft RPM in a vehicle's drivetrain. It's a critical factor in determining final drive ratios and vehicle performance characteristics.

2. How Does the Calculator Work?

The calculator uses the simple hub ratio formula:

Where:

• Wheel RPM — Rotational speed of the wheel
• Driveshaft RPM — Rotational speed of the input driveshaft

Explanation: The ratio shows how many times the wheel rotates for each rotation of the driveshaft, indicating the reduction through the hub assembly.

3. Importance of Hub Ratio

Details: Hub ratio is essential for calculating final drive ratios, understanding torque multiplication, and selecting appropriate gearing for off-road vehicles or performance applications.

4. Using the Calculator

Tips: Enter both wheel RPM and driveshaft RPM as positive numbers. The values can be obtained through direct measurement or from vehicle specifications.

5. Frequently Asked Questions (FAQ)

Q1: What's a typical hub ratio for portal axles?
A: Common portal axle reductions range from 1.5:1 to 2.5:1, depending on the application.

Q2: How does hub ratio affect vehicle performance?
A: Higher ratios increase torque at the wheels but reduce top speed, while lower ratios have the opposite effect.

Q3: Can I use this for non-portal axle vehicles?
A: Yes, it can calculate any wheel-to-driveshaft speed ratio, though standard axles typically have a 1:1 ratio.

Q4: How does hub ratio combine with gear ratio?
A: Final drive ratio is the product of transmission gear ratio, differential ratio, and hub ratio.

Q5: Why would someone want a higher hub ratio?
A: Off-road vehicles benefit from higher ratios for increased torque and ground clearance.