2020 International LT — Transmission & Axle Gear Ratios

Transmission gear ratios

The 2020 International LT offers a range of robust transmission options designed to meet the diverse demands of heavy-duty trucking. From efficient automated manuals to traditional manuals, each transmission provides a unique set of gear ratios optimized for specific applications.

Eaton Fuller Advantage FRO-16210C (Automated Manual Transmission)

Eaton Fuller RTO-16908LL (Manual Transmission)

Allison 4000 Series (Automatic Transmission - specific applications)

Available axle ratios

The choice of axle ratio is critical for optimizing the performance of your 2020 International LT, balancing fuel efficiency with pulling power. International offers a variety of rear axle ratios to suit different operational needs.

How to identify your axle ratio

Identifying the axle ratio of your International LT is crucial for proper maintenance and understanding its performance characteristics. International trucks typically have the axle ratio information on a build sheet or a sticker located on the driver's side door jamb or inside the glove box. This sticker will list various RPO (Regular Production Option) codes, which specify all the factory-installed equipment, including the axle ratio.

For International trucks, the axle code is usually a three-digit alphanumeric code. If you cannot find this sticker or the information is illegible, you can often find a metal tag bolted to one of the differential cover bolts on the rear axle housing. This tag will directly stamped with the axle ratio. Alternatively, knowing your truck's VIN allows an International dealer to provide the exact build specifications and axle ratio information.

Towing vs MPG impact

The axle ratio has a direct and significant impact on both the towing capability and fuel economy of your International LT. A numerically lower axle ratio (e.g., 2.47, 2.64) means the engine performs fewer revolutions to turn the wheels a given distance. This results in lower engine RPMs at cruising speeds, leading to better fuel economy. However, with a numerically lower ratio, the engine has less mechanical advantage, which translates to reduced towing capacity and slower acceleration.

Conversely, a numerically higher axle ratio (e.g., 3.55, 3.73) means the engine will spin at higher RPMs to achieve the same road speed. This provides greater torque multiplication at the wheels, enhancing towing capacity and acceleration. The trade-off is often a decrease in fuel efficiency due to the engine working harder and consuming more fuel at higher RPMs.

For heavy-duty trucks like the International LT, choosing the right balance is key. Trucks primarily used for long-haul, light-load applications will benefit from a lower axle ratio for optimal fuel economy. Vehicles regularly hauling heavy loads or operating in challenging terrains will require a higher axle ratio to maximize towing performance and durability.

Common issues

While the driveline components of an International LT are built for heavy-duty use, common issues can arise over time. These include:

• Ring and Pinion Whine: This is often heard as a howling or whining noise that changes with road speed and load. It can be caused by improper gear mesh, worn gears, or insufficient lubrication. Left unaddressed, it can lead to premature failure.
• Carrier Bearing Wear: The carrier bearings support the differential carrier within the axle housing. Wear can manifest as a rumble, growl, or vibration, particularly noticeable during acceleration or deceleration. Failed carrier bearings can lead to severe damage to the differential.
• Limited-Slip Clutch Wear (if equipped): For trucks equipped with limited-slip differentials, the internal clutches can wear out over time. Symptoms may include a chattering or clunking noise when turning, or a noticeable decrease in traction in slippery conditions. Servicing usually involves replacing the clutch pack and using the correct friction modifier in the differential fluid.

Regular maintenance, including proper differential fluid changes and inspections, can help mitigate these issues and extend the life of your driveline components.

Find a driveline shop on Repairius.