2015 Jeep Wrangler Transmission & Axle Gear Ratios

Transmission gear ratios

The 2015 Jeep Wrangler was available with two transmission options: a 6-speed manual and a 5-speed automatic.

6-Speed Manual Transmission (NSG370)

This robust manual transmission was standard on most Wrangler models, offering a traditional and engaging driving experience.

5-Speed Automatic Transmission (WA580/545RFE)

Available as an option, this automatic transmission provided a smoother, more convenient driving experience, especially in stop-and-go traffic or during off-road excursions where precise throttle control is beneficial.

Available axle ratios

The 2015 Jeep Wrangler offered a variety of axle ratios, allowing owners to optimize their vehicle for different driving conditions, from daily commuting to serious off-road adventures and towing.

How to identify your axle ratio

Identifying the axle ratio of your 2015 Jeep Wrangler is crucial for maintenance, upgrades, and understanding your vehicle's capabilities. Here are the common methods:

• Door-Jamb RPO Sticker (GM Method): While primarily a GM method, some Jeep owners might find a build sheet or sticker with RPO codes that list the axle ratio. Look for a three-digit code beginning with 'D' (e.g., DMZ, DNP, DME).
• Axle Tag (Ford/Ram Method): Although not as common on newer Jeeps, older models or replacement axles might have a metal tag attached to one of the differential cover bolts. This tag will typically stamp the axle ratio (e.g., 3.73).
• VIN Decoder: Using a VIN decoder online or through a dealership can often provide a comprehensive list of your vehicle's factory specifications, including the axle ratio.
• Counting Revolutions (Manual Method): Jack up the rear of the vehicle, mark one of the tires and the driveshaft. Rotate the tire two full revolutions and count how many times the driveshaft rotates. This count will approximate your axle ratio (e.g., just under 4 rotations for a 3.73 ratio).

Towing vs MPG impact

The axle ratio significantly impacts both towing capability and fuel economy. It's a trade-off that manufacturers balance to suit different vehicle applications.

• Numerically Lower Ratio (e.g., 3.21): A numerically lower ratio means the engine turns fewer times for each revolution of the wheels. This results in lower RPMs at highway speeds, leading to better fuel economy. However, it also means less mechanical advantage for accelerating or pulling heavy loads, making it less ideal for towing.
• Numerically Higher Ratio (e.g., 4.10): Conversely, a numerically higher ratio means the engine turns more times for each wheel revolution. This provides greater mechanical advantage, offering quicker acceleration and significantly more towing power. The trade-off is higher engine RPMs at highway speeds, which generally leads to poorer fuel economy.
• Balanced Ratio (e.g., 3.73): This ratio attempts to strike a balance between towing capacity and fuel efficiency, making it a popular choice for those who need to tow occasionally but also care about their daily driving fuel consumption.

Common issues

While the 2015 Jeep Wrangler's drivetrain is generally robust, certain components, like those in the axle assemblies, can experience wear and tear over time.

• Ring & Pinion Whine: A common issue, especially as mileage increases, is a whining sound from the differential, particularly at certain speeds or under load. This can indicate wear on the ring and pinion gears, incorrect gear mesh, or improper backlash.
• Carrier Bearing Wear: The bearings that support the differential carrier can wear out, leading to humming or growling noises, especially when turning. Neglecting this can lead to further damage within the differential.
• Limited-Slip Clutch Wear: For Wranglers equipped with a limited-slip differential, the internal clutches can wear out over time. This will manifest as a loss of the limited-slip function, potentially causing one wheel to spin freely when traction is lost, and sometimes chattering or binding during turns.

Regular differential fluid changes using the correct type of fluid (including friction modifier for limited-slip differentials) are crucial for extending the life of these components.

Find a driveline shop on Repairius.