Details

• Brand:

  

  

• SKU:

  ML3Z-4209-J

• Positions: Rear
• Other Names:

  Gear And Pinion Assembly Driving

• Description:

  This is the genuine Ford differential ring and pinion set for the 2015-2025 F-150 with the 9.75 inch rear axle, a 3.55 drive ratio and limited slip. Ford catalogs it under base number 4209 with the names Differential Ring And Pinion, Ring and Pinion, and Gear And Pinion Assembly Driving, and specifies a 9.75 inch ring gear, 3.55 axle ratio and three quarter floating axle. It supersedes FL3Z-4209-C and ML3Z-4209-C. The ring and pinion is the hypoid gear set inside the rear differential that turns driveshaft rotation ninety degrees into axle shaft rotation while multiplying torque by the axle ratio. The pinion drives the ring gear, the ring gear drives the differential case, and the case drives the axle shafts. It is the single most highly loaded gear mesh in the driveline. Failures announce themselves as a howl or whine that changes with vehicle speed and varies between coast and load, a chattering or grinding from the rear axle, metal flake in the axle lubricant, and in the worst case a locked rear axle after a tooth has broken. Common causes are low or contaminated gear oil, water intrusion through a failed axle vent, heavy towing beyond rating, and improper setup after a previous rebuild. The ring and pinion must be installed as a matched set, never mixed with used gears, and setup requires correct pinion depth, pinion bearing preload and backlash verified with a dial indicator and a gear pattern check. Both ratio and axle diameter must match the truck.

• Applications: 9.75 Axle. W/LIMITED SLIP.
• Replaces:

  fl3z4209c, ml3z4209c

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