1. Vehicle Identification Number (VIN) Decoder:
* Most Accurate (if data is available): A VIN decoder, either online (many free and paid options exist) or through a Ford dealership, can often provide the rear axle ratio. This is the most reliable method if the information is included in the VIN database. However, not all VIN decoders include this detail.
2. Differential Tag:
* Most Reliable if Accessible: Look for a tag on the differential housing itself. This tag usually contains the gear ratio (e.g., 3.73, 4.10, etc.). You'll likely need to get under the vehicle to see it. The tag might be located on the top or side of the differential. It may be covered in dirt and grime, so clean it carefully before trying to read it.
3. Jacking Up and Rotating the Wheels:
* Requires Tools and Calculation: This method is less precise but works if you don't find the tag.
* Securely jack up one rear wheel (safety first!).
* Put the vehicle in neutral or park (automatic transmission).
* Rotate the wheel exactly one full turn.
* Count how many times the driveshaft rotates.
* The number of driveshaft rotations is the *numerical* part of the gear ratio. The ratio is then typically expressed as 'x:1', where x is the number of driveshaft rotations. For example, if the driveshaft turns 3.73 times for every wheel rotation, the gear ratio is 3.73. This method requires careful counting and wheel rotation.
4. Owner's Manual:
* Least Reliable: While some owner's manuals list the gear ratio, it's not always included.
Important Considerations:
* Safety: When working under a vehicle, always use jack stands and follow proper safety procedures.
* Accuracy: The wheel rotation method can be less accurate due to tire size variations and measurement errors. The differential tag or VIN decoder are far more reliable.
* Variations: Ford used different rear axle ratios across different models, years, and trim levels. The method you choose must be specific to your vehicle.
If you're having trouble locating the information, providing the year, make, model, and trim level of your Ford will greatly assist in helping you find the correct gear ratio.
