Flywheel Ring Gear Cummins 3901774 | J901774, CU3901774

High-Performance Flywheel Ring Gear for Cummins B-Series Engines

Ensure smooth, reliable ignition and starter engagement with this heavy-duty Flywheel Ring Gear (Part Number: 3901774). Specifically engineered for Cummins 4BT 3.9L and 6BT 5.9L engines, this ring gear is manufactured from high-strength carbon steel to withstand the intense rotational forces and heat generated during engine startup.

Key Features & Benefits

• Precise Starter Engagement: Features 159 precision-cut teeth designed to mesh seamlessly with your starter motor pinion, preventing slippage and premature wear.
• Heavy-Duty Construction: Built from premium-grade steel, heat-treated for maximum hardness and wear resistance to extend the service life of your drive system.
• Exact Fitment: Manufactured to strict dimensional tolerances, ensuring a perfect press-fit onto your existing flywheel.

Technical Specifications

• Part Number: 3901774
• Number of Teeth: 159
• Width: 15 mm (approx. 0.59 inches)
• Inner Diameter: 385 mm (approx. 15.09 inches)
• Outer Diameter: 408 mm (approx. 16.06 inches)

Engine Compatibility

This flywheel ring gear is compatible with a wide range of Cummins B-Series and ISB engines, including:

• Cummins 4BT 3.9L
• Cummins 6BT 5.9L
• Cummins ISB 5.9L / 6.7L
• Cummins QSB 3.9L / 4.5L / 5.9L