2021 Jeep Gladiator Transmission & Axle Gear Ratios

Transmission gear ratios

The 2021 Jeep Gladiator comes with two transmission options: an 8-speed automatic (850RE) and a 6-speed manual (D478). Both are robust units designed to handle the rigors of off-road driving and towing.

8-speed Automatic (850RE)

6-speed Manual (D478)

Available axle ratios

The 2021 Jeep Gladiator offers several axle ratios, allowing owners to optimize their vehicle for specific needs, whether it's heavy towing, better fuel economy, or a balanced approach.

How to identify your axle ratio

Identifying your Jeep Gladiator's axle ratio is crucial for proper maintenance, upgrades, or diagnosing issues. For most Stellantis (formerly FCA) vehicles, including the Jeep Gladiator, you'll want to look for the build sheet or a sticker/label that indicates the axle code. While some manufacturers place an RPO sticker on the door jamb, the most reliable method for your Gladiator is often to retrieve the full build sheet using your VIN. Many Jeep dealerships can provide this, or you can use online VIN decoders that access factory build data. Alternatively, a physical inspection of the axle housing may reveal a tag with the ratio stamped on it, typically on the differential cover bolts on the rear axle, although this can be harder to read due to dirt and rust.

Towing vs MPG impact

The choice of axle ratio significantly impacts your vehicle's performance characteristics. Generally:

• Numerically lower axle ratios (e.g., 3.73): These ratios mean the engine rotates fewer times for each rotation of the wheels. This results in better fuel economy on the highway as the engine operates at lower RPMs. However, it also means less mechanical advantage, which can reduce towing capacity and make the vehicle feel less responsive off the line, especially with heavy loads.

• Numerically higher axle ratios (e.g., 4.10): These ratios mean the engine rotates more times for each rotation of the wheels. This provides greater torque multiplication, which is beneficial for towing heavy loads, off-roading, and quicker acceleration. The trade-off is often reduced fuel economy due to higher engine RPMs at cruising speeds.

For the 2021 Jeep Gladiator, the 4.10 ratio found in the Rubicon and Mojave (manual) models is specifically designed for enhanced off-road performance and superior towing capabilities, sacrificing some highway fuel efficiency. The 3.73 ratio offered on other trims provides a good balance for daily driving and moderate towing.

Common issues

While the Gladiator's drivetrain is generally robust, specific issues, especially with altered tire sizes or heavy use, can arise:

• Ring & Pinion Whine: A distinct howling or whining noise that changes with vehicle speed (not engine RPM) can indicate worn or improperly set up ring and pinion gears. This is more common after re-gearing with aftermarket parts or if the differential fluid is neglected.
• Carrier Bearing Wear: The bearings supporting the differential carrier can wear out, leading to a rumbling or grinding noise, especially during turns or when accelerating. This can be exacerbated by abuse or lack of lubrication.
• Limited-Slip Clutch Wear (if equipped): If your Gladiator has a limited-slip differential (Trac-Lok), the clutch packs can wear over time, leading to a loss of traction in slippery conditions. Symptoms can include shuddering or chattering from the rear end during tight turns.

Regular differential fluid changes with the correct type of fluid (including friction modifier for limited-slip units) are crucial for longevity.

Find a driveline shop on Repairius.