2019 Jeep Grand Cherokee Transmission & Axle Gear Ratios

Transmission gear ratios

The 2019 Jeep Grand Cherokee was equipped with the sophisticated TorqueFlite eight-speed automatic transmission across all trims and engine options. This transmission, known for its smooth shifts and efficiency, is derived from the ZF 8HP transmission.

Available axle ratios

The 2019 Jeep Grand Cherokee offered a range of axle ratios, catering to different driving needs, from fuel efficiency to enhanced towing and off-road capability. The availability of specific ratios often depended on the engine, trim level, and optional packages.

Note: The RPO/Axle codes are typically found on a sticker in the glove compartment or on the driver's side door jamb.

How to identify your axle ratio

Identifying your Jeep Grand Cherokee's axle ratio is crucial for proper maintenance, upgrades, or diagnosing issues. For 2019 models, the easiest way to find this information is by checking the RPO (Regular Production Option) sticker. This sticker is usually located on the inside of the glove compartment, or on the driver's side door jamb.

Look for a three-digit code that starts with "DM" (e.g., DMB, DME, DMH, DMK). These codes correspond to specific axle ratios as listed in the table above. If you cannot locate the RPO sticker or the code is unreadable, you may need to contact a Jeep dealership with your VIN, or physically inspect the axle housing (though this is less common for newer vehicles as axle tags are becoming less prevalent).

Towing vs MPG impact

Choosing the right axle ratio involves a trade-off between towing capability and fuel economy. This is a fundamental principle in vehicle dynamics:

• Numerically Lower Ratio (e.g., 3.09:1): A numerically lower axle ratio means the engine spins fewer revolutions per minute (RPM) for a given road speed. This reduces fuel consumption, leading to better fuel economy. However, it also means less mechanical advantage for acceleration and towing, making the vehicle feel less responsive under load. It's ideal for highway cruising and light-duty applications.

• Numerically Higher Ratio (e.g., 3.45:1, 3.70:1): Conversely, a numerically higher axle ratio causes the engine to spin more RPMs for the same road speed. This provides greater towing capacity and improved acceleration, as the engine can more easily move a heavy load from a standstill. The trade-off is increased fuel consumption, particularly at highway speeds. These ratios are preferred for heavy towing, off-road driving, or performance applications where quick acceleration is desired.

For the 2019 Grand Cherokee, the 3.09:1 ratio offers the best balance for daily driving and fuel efficiency, while the 3.45:1 and 3.70:1 ratios are better suited for those who frequently tow or engage in more demanding driving conditions.

Common issues

While the drivetrain components of the 2019 Jeep Grand Cherokee are generally robust, like any mechanical system, they can develop issues over time. Some common problems associated with differentials and axles include:

• Ring and Pinion Whine: A persistent high-pitched hum or whine that changes with vehicle speed (and sometimes load) is often indicative of wear or improper setup of the ring and pinion gears within the differential. This can be caused by insufficient lubrication, improper backlash, or worn bearings.

• Carrier Bearing Noise: A rumbling or roaring noise, especially noticeable at certain speeds, can point to worn carrier bearings. These bearings support the differential carrier within the axle housing. Ignoring this can lead to further damage to the differential.

• Limited-Slip Clutch Wear: If your Grand Cherokee is equipped with a limited-slip differential (common on higher trims or with certain off-road packages), the clutch packs can wear out over time. Symptoms include a chattering or clunking sound when turning tightly at low speeds, or a loss of traction assistance in slippery conditions. Regular fluid changes with the correct friction modifier are essential for these differentials.

Prompt diagnosis and repair by a qualified technician are crucial to prevent more extensive and costly damage to your vehicle's driveline.

Find a driveline shop on Repairius.