2020 Ram 3500 Transmission & Axle Gear Ratios

Transmission gear ratios

The 2020 Ram 3500 offers a few transmission options, depending on the engine choice. The primary transmissions are the 68RFE automatic for the 6.4L HEMI V8 and the Aisin AS69RC automatic for the 6.7L Cummins Turbo Diesel.

68RFE Automatic Transmission (6.4L HEMI V8)

The 68RFE is a 6-speed automatic transmission designed to handle the power and torque of the HEMI engine, offering a good balance of towing capability and everyday drivability.

Aisin AS69RC Automatic Transmission (6.7L Cummins Turbo Diesel)

The Aisin AS69RC is a heavy-duty 6-speed automatic transmission specifically paired with the high-output 6.7L Cummins Turbo Diesel engine. It's engineered for maximum durability and towing performance.

Available axle ratios

The 2020 Ram 3500 offers a variety of axle ratios to optimize for different uses, from heavy-duty towing to improved fuel efficiency. The availability often depends on the chosen engine, trim level, and specific packages.

How to identify your axle ratio

Identifying the axle ratio on your 2020 Ram 3500 is crucial for proper maintenance, upgrades, or simply understanding your truck's capabilities. For Ram trucks, the most common place to find this information is on the door-jamb sticker, often located on the driver's side. Look for a build sheet or RPO (Regular Production Option) code sticker. The axle ratio will be represented by specific three-digit codes like DMJ for 3.73 or DMP for 4.10. These codes are part of a longer list of options. Alternatively, some older or commercial Ram trucks might have an axle tag bolted to the differential cover, which would directly display the ratio. If neither of these methods works, a Ram dealership can often provide a build sheet using your VIN, which will detail all the installed options, including the axle ratio.

Towing vs MPG impact

The choice of axle ratio significantly impacts your 2020 Ram 3500's performance characteristics, specifically its towing capacity and fuel economy.

A numerically lower axle ratio (e.g., 3.73) means the engine will spin at lower RPMs at a given road speed. This generally leads to better fuel economy on the highway, as the engine isn't working as hard. However, it also means less mechanical advantage for acceleration and towing, requiring the engine to work harder and downshift more frequently when hauling heavy loads.

Conversely, a numerically higher axle ratio (e.g., 4.10) means the engine will spin at higher RPMs at the same road speed. This provides greater mechanical advantage, resulting in improved acceleration and significantly enhanced towing capability, allowing the truck to handle heavier loads with less strain. The trade-off is typically lower fuel economy, especially at highway speeds, as the engine is operating at higher revolutions.

For the 2020 Ram 3500, if your primary use involves frequent and heavy towing, the 4.10 ratio is generally preferred. If your truck is more for lighter hauling and daily driving with an emphasis on fuel economy, the 3.73 ratio might be a better fit, offering a balanced approach.

Common issues

While Ram's heavy-duty axles are built to be robust, certain issues can arise over time, especially with neglect or extreme use:

• Ring & Pinion Whine: A common symptom of worn gears or improper installation (after a repair). This often presents as a howling or whining noise that changes with vehicle speed and throttle input. Early detection is key, as continued use can lead to catastrophic failure.
• Carrier Bearing Wear: The carrier bearings support the differential carrier within the axle housing. Wear can lead to a rumbling or vibrating noise, often felt through the floorboards or steering wheel, and can worsen when turning. This can be caused by heavy loads, lack of lubrication, or simply high mileage.
• Limited-Slip Clutch Wear: Many Ram 3500s come with an optional limited-slip differential. Over time, the clutch packs within this differential can wear out, leading to a loss of traction in low-traction situations or a chattering noise from the rear axle, especially during slow turns. Regular fluid changes with the correct friction modifiers are essential for longevity.

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