Ford 9 in. Aluminum 28-Spline Helical Gear LSD Third Member Assembly 3.70:1 Ratio

The Ford 9 in. Aluminum Helical Gear LSD Third Member Assembly by Speedmaster is a high-performance differential carrier designed for Ford 9-inch rear axles. This aluminum third member assembly features a helical gear configuration with a 3.70:1 gear ratio and 28-spline engagement, engineered to deliver smooth power transmission and improved torque handling in performance and street-driven vehicles.

This assembly is ideal for hot rod builders, performance enthusiasts, and street-driven Ford vehicles requiring a robust limited-slip differential (LSD) solution. The aluminum construction reduces weight compared to cast-iron alternatives, while the helical gear design provides quieter operation and superior load distribution. The 3.70:1 ratio offers a balance between acceleration and highway cruising, making it suitable for both street and light track applications. Compatible with Ford 9-inch rear axles, this third member assembly simplifies installation for restoration and upgrade projects.

Key Features & Benefits

• Aluminum Construction: Lightweight aluminum design reduces overall vehicle weight compared to traditional cast-iron third members.
• Helical Gear Design: Helical gears provide quieter, smoother power delivery and superior load distribution during acceleration.
• 3.70:1 Gear Ratio: Balanced ratio optimizes acceleration while maintaining reasonable highway cruising speeds.
• 28-Spline Engagement: Standard 28-spline configuration ensures proper axle shaft compatibility with Ford 9-inch applications.
• LSD (Limited-Slip) Differential: Limited-slip design improves traction by distributing torque between wheels, enhancing handling and acceleration.

Specifications

Ideal Applications

• Hot rod and custom vehicle builds requiring lightweight performance differentials
• Street-driven Ford 9-inch rear axle upgrades and restorations
• Performance vehicles seeking improved traction and acceleration response
• DIY rear axle assembly and differential replacement projects