2017 Jeep Wrangler: Transmission & Axle Gear Ratios

Transmission gear ratios

For 2017, the Jeep Wrangler (JK) was available with two transmissions: a 6-speed manual and an optional 5-speed automatic.

6-Speed Manual Transmission (NSG370)

5-Speed Automatic Transmission (W5A580)

Available axle ratios

The 2017 Wrangler offered several axle ratios, tailored to different models and purposes. The choice of ratio significantly impacts both off-road capability and on-road fuel efficiency.

How to identify your axle ratio

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

• Build Sheet/Window Sticker: The easiest way is to check the original window sticker or request a build sheet from Jeep using your VIN. This will list the "Axle Ratio" as a standard or optional feature.
• Axle Tag: Look for a small metal tag bolted to the differential cover on the rear axle. This tag has codes stamped into it, which will include the ratio (e.g., "3.73").
• VIN Decoder: Several online VIN decoders can provide a detailed build sheet for your specific Wrangler, which will include the factory-installed axle ratio.

Unlike GM vehicles, Jeeps do not list RPO codes on a door-jamb sticker.

Towing vs MPG impact

The axle ratio has a direct and inverse relationship between towing performance and fuel economy.

• Numerically Lower Ratios (e.g., 3.21): These are often called "taller" gears. The engine turns at a lower RPM at any given speed, which reduces fuel consumption on the highway. However, this comes at the cost of reduced pulling power, making it less ideal for heavy towing or serious rock crawling.
• Numerically Higher Ratios (e.g., 4.10): Known as "shorter" gears, these multiply engine torque more effectively. This provides much better acceleration and low-speed pulling power, which is ideal for towing heavy loads or tackling challenging off-road obstacles. The trade-off is higher engine RPM on the highway, leading to lower fuel economy.

For a 2017 Wrangler, a 3.73 ratio offers a great compromise for a daily-driven vehicle that also sees frequent weekend trail use. For dedicated rock crawlers or those who have added larger tires, the 4.10 ratio is superior.

Common issues

While the Dana axles used in the 2017 Wrangler are generally robust, some issues can arise, particularly on modified vehicles or those used heavily off-road.

• Ring & Pinion Whine: A whining noise from the differential that changes pitch with vehicle speed can indicate improper gear setup or worn ring and pinion gears. This often requires a full rebuild of the differential by a specialist.
• Carrier Bearing Failure: The bearings that support the differential carrier can wear out, leading to a humming or rumbling noise. If left unaddressed, this can cause catastrophic failure of the axle internals.
• Limited-Slip Clutch Wear: On models equipped with the optional Trac-Lok limited-slip differential, the internal clutch packs can wear out over time, reducing their effectiveness. This is often noticed as a loss of traction in slippery conditions where one wheel spins freely.

Find a driveline shop on Repairius.