Eaton 913A586 Detroit Truetrac Helical Gear Limited Slip Differential - Ford 9 Inch, 31 Spline

The Eaton 913A586 Detroit Truetrac is a helical gear limited slip differential designed for Ford 9-inch axles with 31-spline axle shafts and ring gear ratios of 3.25 and up. This helical-gear style, limited-slip differential maximizes wheel traction and enhances driving characteristics with maintenance-free, smooth, automatic operation in forward and reverse.

Key Features:

• Patented design of parallel-axis planetary helix gears provides quiet, automatic splitting of torque
• Fully automatic operation that can transfer up to 3.5 times more torque to the high traction wheel
• Manufactured with forged and heat-treated cases with extremely high-quality gearing
• Maintenance-free helical cut gears requiring only regular lube changes
• No wearable clutch packs or friction plates to replace
• 31-spline configuration with 1.32-inch axle shaft diameter
• Compatible with ring gear ratios 3.25:1 and higher

How It Works:

The Detroit Truetrac operates as a standard differential under normal driving conditions, allowing one wheel to spin faster or slower as necessary. When a wheel encounters a loss of traction, the gear separation forces take effect and transfer torque to the high-traction wheel. The typical Truetrac differential will consistently deliver approximately three-fold the torque of the slipping wheel to the gripping wheel.

Installation Notes:

Eaton recommends a petroleum/mineral based GL-5 80W90 gear oil for all Truetrac differentials. Do not use synthetic gear oil or friction modifiers. In most cases, the Truetrac units work with factory (stock, OE) bearings.

Ideal for street performance, off-road, towing, and racing applications where reliable traction is essential without the harshness of a full locker. Suitable for small trucks, minivans, SUVs, half-ton trucks, vans, and passenger cars.