2017 Ram 1500 Transmission & Axle Gear Ratios

Transmission gear ratios

The 2017 Ram 1500 was offered with two primary transmission options: the 8-speed automatic (8HP70 or 8HP75, depending on application) and, for certain configurations, a 6-speed automatic (65RFE). The 8-speed automatic is a highly regarded transmission for its smooth shifts and efficiency.

8-Speed Automatic (8HP70/8HP75)

6-Speed Automatic (65RFE)

Available axle ratios

The 2017 Ram 1500 offered a variety of axle ratios to cater to different needs, from fuel economy to heavy-duty towing.

How to identify your axle ratio

Identifying your Ram 1500's axle ratio can be done in a few ways:

• Door-Jamb RPO Sticker: For later model Rams, check the sticker on the driver's side door jamb for a list of RPO (Regular Production Option) codes. Look for a three-digit code starting with "DM" (e.g., DMH for 3.21, DME for 3.55, DMK for 3.92). These codes represent the final drive ratio.
• Axle Tag: Older Ram trucks often have a metal tag attached to one of the differential cover bolts on the rear axle. This tag will typically stamp the gear ratio directly on it.
• VIN Decoder: A more reliable method is to use a VIN decoder tool (many are available online). Entering your truck's VIN will often provide a detailed breakdown of all factory-installed options, including the axle ratio.

Towing vs MPG impact

The choice of axle ratio significantly impacts your truck's performance characteristics:

• Numerically Lower Ratio (e.g., 3.21): This means the engine has to turn fewer times for each rotation of the wheels. This is generally beneficial for better fuel economy on the highway, as the engine operates at lower RPMs. However, it provides less torque multiplication, meaning the engine has to work harder to get the truck moving or to pull heavy loads, resulting in reduced towing capability.
• Numerically Higher Ratio (e.g., 3.92): With a higher ratio, the engine turns more times for each wheel rotation. This provides greater torque multiplication, making the truck feel more powerful off the line and significantly improving its towing capacity. The engine can more easily handle heavy loads. The trade-off, however, is reduced fuel economy, particularly at highway speeds, as the engine runs at higher RPMs.
• Balanced Ratio (e.g., 3.55): This ratio attempts to strike a balance between towing capability and fuel efficiency, often being a popular choice for truck owners who occasionally tow but also use their vehicle as a daily driver.

Common issues

While the Ram 1500 axles are generally robust, some common issues can arise with prolonged use or improper maintenance:

• Ring & Pinion Whine: A common symptom of worn or improperly set up ring and pinion gears is a distinct howling or whining noise, especially when decelerating or at certain speeds. This can be caused by improper backlash, worn bearings, or damaged gear teeth.
• Carrier Bearing Wear: The carrier bearings support the differential carrier within the axle housing. Wear in these bearings can lead to noise, vibration, and eventually differential failure if not addressed. A rumbling or whirring sound that changes with vehicle speed is a common indicator.
• Limited-Slip Clutch Wear: If your Ram is equipped with a limited-slip differential, the clutch packs within it can wear out over time. This can result in a loss of the limited-slip function (one wheel spinning freely in low-traction situations) or chatter/groaning noises when turning at low speeds.

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