2015 Ford Explorer Transmission & Axle Gear Ratios

Transmission gear ratios

The 2015 Ford Explorer was primarily equipped with the 6F50 and 6F55 six-speed automatic transmissions, each offering a blend of performance and efficiency. The 6F50 was typically paired with the naturally aspirated engines, while the more robust 6F55 was found with the EcoBoost engines, particularly the 3.5L EcoBoost. Both transmissions share very similar internal gear ratios.

6F50 / 6F55 Automatic Transmission

Available axle ratios

Ford offered a range of axle ratios for the 2015 Explorer to cater to different needs, from improved fuel economy to enhanced towing capabilities. The choice of axle ratio significantly impacts the vehicle's character.

How to identify your axle ratio

Identifying your Ford Explorer's axle ratio is crucial for proper maintenance, parts replacement, or performance modifications. For 2015 Ford Explorers, the easiest way to determine the axle ratio is by checking the door jamb sticker on the driver's side. Look for the "AXLE" code. This two-digit code corresponds to the installed axle ratio.

Additionally, some Ford vehicles may have an axle tag attached to one of the differential cover bolts. This metal tag will stamp the gear ratio directly on it (e.g., "3.39"). While less common on newer vehicles like the 2015 Explorer, it's worth checking if the door jamb sticker is unreadable or missing.

For a definitive answer, especially if you suspect modifications, a Ford dealership can typically provide the original build sheet information using your VIN.

Towing vs MPG impact

The axle ratio plays a significant role in how your 2015 Ford Explorer performs in terms of towing and fuel economy. It's a trade-off: a numerically higher ratio (e.g., 3.39) will generally provide better acceleration and towing capacity, while a numerically lower ratio (e.g., 3.16) will typically result in better fuel economy at highway speeds.

• Higher Ratio (e.g., 3.39): This means the engine will rev higher at a given road speed, providing more torque multiplication at the wheels. This is beneficial for towing heavy loads, accelerating quickly, and driving in hilly terrain. The downside is that the increased engine RPMs will generally lead to lower fuel efficiency, especially during highway cruising.
• Lower Ratio (e.g., 3.16): With a numerically lower ratio, the engine will spin at lower RPMs at a given road speed. This reduces engine work and fuel consumption, making it ideal for drivers who prioritize highway fuel economy and don't frequently tow heavy loads. The trade-off is slightly reduced off-the-line acceleration and less available torque for heavy towing.

For the 2015 Ford Explorer, the 3.16 ratio was specifically paired with the more powerful 3.5L EcoBoost in the Sport and Platinum trims, allowing those models to leverage the engine's substantial power while maintaining reasonable highway fuel economy for a performance-oriented SUV.

Common issues

While generally reliable, the drivetrain components of the 2015 Ford Explorer can experience some issues over time, particularly related to the differential and axles:

• Ring & Pinion Whine: A persistent whining noise that changes with vehicle speed (and sometimes load) can indicate wear on the ring and pinion gears within the differential. This often starts subtly and can worsen if not addressed.
• Carrier Bearing Wear: The bearings that support the differential carrier can wear out, leading to a humming or growling noise, especially noticeable at certain speeds. If left unaddressed, it can lead to further differential damage.
• Limited-Slip Clutch Wear (if equipped): Explorers equipped with a limited-slip differential can experience wear of the internal clutch packs. Symptoms might include chattering or clunking noises during turns, especially at low speeds, or a noticeable decrease in traction ability in slippery conditions. Regular fluid changes with the correct friction modifier are essential to prolong the life of these components.

Regular differential fluid changes with the manufacturer-recommended fluid and friction modifiers (if applicable) are crucial for prolonging the life of these components.

Find a driveline shop on Repairius.