2014 Ram 2500: Transmission & Axle Gear Ratios

Transmission Gear Ratios

Two main automatic transmissions were available for the 2014 Ram 2500, each paired with specific engines.

66RFE Six-Speed Automatic

This transmission was standard with the 5.7L HEMI V8 engine.

68RFE Six-Speed Automatic

This heavy-duty transmission was paired with the 6.7L Cummins Turbo Diesel engine.

Available Axle Ratios

The axle ratio is the final link in your driveline, multiplying torque one last time before it reaches the wheels. The ratio you have determines your truck's balance between towing power and fuel efficiency.

Note: Availability could vary based on trim level (Tradesman, SLT, Laramie, etc.) and other optional packages.

How to Identify Your Axle Ratio

Knowing your specific axle ratio is crucial when ordering parts or diagnosing issues. Here’s how to find it:

• VIN Decoder: The easiest method is to use an online VIN decoder. This will provide a full build sheet for your specific truck, including the axle ratio it left the factory with.
• Axle Tag (Most Reliable): Look for a small metal tag bolted to the differential cover (the pumpkin-shaped housing in the center of your rear axle). This tag will have several numbers stamped on it. The ratio is often clearly stamped (e.g., "3 73" for a 3.73:1 ratio). This is the most accurate method, as it reflects the hardware actually on the truck.
• Glove Box Sticker: Unlike GM, Ram does not typically use a door-jamb sticker with RPO codes. Instead, look for a build sheet or sticker inside the glove compartment that lists your truck's standard and optional equipment. It may list the axle ratio directly.

Towing vs. MPG Impact

The trade-off between power and efficiency is directly tied to the axle ratio number.

• Numerically Lower Ratios (e.g., 3.42:1): These are considered "taller" gears. The engine turns fewer RPMs at a given highway speed, which reduces fuel consumption. This is ideal for trucks that spend most of their time cruising on the highway with light or no loads. Towing capacity will be reduced compared to higher ratios.

• Numerically Higher Ratios (e.g., 4.10:1): These are "shorter" gears. They provide greater torque multiplication, making it easier to get a heavy load moving from a standstill. This is best for maximizing your truck's towing and hauling capacity. The trade-off is higher engine RPMs at highway speeds, resulting in lower fuel economy.

• Balanced Ratios (e.g., 3.73:1): This is the middle-ground option, offering a good compromise between respectable towing capability and manageable highway fuel economy. It's a jack-of-all-trades ratio suitable for a mix of daily driving and occasional heavy work.

Common Issues

While the AAM (American Axle & Manufacturing) axles used in the 2014 Ram 2500 are robust, some issues can arise, particularly with high mileage or heavy use.

• Pinion Bearing Whine: The most common symptom of axle trouble is a whining or howling noise that changes pitch with vehicle speed (not engine RPM). This is often caused by a worn pinion bearing. If the noise changes when you accelerate versus decelerate, it points strongly to a bearing or gear setup issue.
• Carrier Bearing Failure: Similar to pinion whine, a worn carrier bearing can cause a deep rumbling or grinding noise from the rear of the truck. This requires disassembling the differential to replace.
• Limited-Slip Clutch Wear: If your truck is equipped with an anti-spin or limited-slip differential (LSD), the internal clutches can wear out over time. A symptom is a "one-wheel peel," where only one rear tire spins when you accelerate hard on a loose surface.

If you hear any unusual noises from your driveline, it’s critical to have it inspected promptly to avoid more catastrophic and expensive failures.

Find a driveline shop on Repairius.