2020 Chevrolet Silverado 1500 Transmission & Axle Gear Ratios

Transmission gear ratios

The 2020 Chevrolet Silverado 1500 offered a variety of transmission options, each designed to optimize performance and fuel economy for different applications. Below are the internal gear ratios for each available transmission.

6-speed automatic (Hydra-Matic 6L80)

8-speed automatic (Hydra-Matic 8L90)

10-speed automatic (Hydra-Matic 10L80)

Available axle ratios

The axle ratio significantly impacts the truck's performance characteristics, balancing between towing capability and fuel efficiency. Here are the common axle ratios available for the 2020 Silverado 1500.

How to identify your axle ratio

For General Motors vehicles like the 2020 Chevrolet Silverado 1500, the easiest way to identify your vehicle's axle ratio is by checking the Service Parts Identification (SPID) label, commonly referred to as the RPO (Regular Production Option) sticker. This sticker is typically found on the inside of the glove compartment door, but can also sometimes be located on the driver's side door jamb or under the hood. Look for codes starting with "GU" or "GT" followed by a number. For example, GU5 indicates a 3.23:1 ratio, and GU6 indicates a 3.42:1 ratio.

If the sticker is missing or unreadable, you can sometimes determine the ratio by looking for an axle tag attached to one of the differential cover bolts on the rear axle. This tag will have the ratio stamped on it. Alternatively, a Chevrolet dealership can provide the build sheet for your specific VIN, which will list all installed RPOs, including the axle ratio.

Towing vs MPG impact

The choice of axle ratio is a critical factor in determining a truck's performance. A numerically lower axle ratio (e.g., 3.23:1) means the engine will operate at lower RPMs at a given road speed. This generally translates to better fuel economy, as the engine isn't working as hard. However, it also means less mechanical advantage for accelerating or pulling heavy loads, reducing towing capacity.

Conversely, a numerically higher axle ratio (e.g., 3.73:1) provides more mechanical advantage, allowing the engine to put more torque to the wheels. This results in quicker acceleration and significantly improved towing capacity, as the engine operates at higher RPMs. The trade-off is a decrease in fuel efficiency, as the engine is working harder and consuming more fuel at highway speeds.

For the 2020 Silverado 1500, the 3.23:1 is ideal for drivers prioritizing fuel economy and who do minimal towing. The 3.42:1 offers a balanced approach, suitable for daily driving and moderate towing. The 3.73:1, often found with the Max Trailering Package, is the best choice for those who frequently tow heavy loads and need maximum pulling power.

Common issues

While the drivetrains of the 2020 Silverado 1500 are generally robust, some common issues can arise with prolonged use or improper maintenance:

• Ring and Pinion Whine: A persistent high-pitched whine that increases with vehicle speed can indicate wear on the ring and pinion gears. This often suggests improper gear mesh, worn bearings, or insufficient lubrication.
• Carrier Bearing Issues: Problems with the carrier bearings can manifest as a growling or humming noise, especially when accelerating or decelerating. If left unaddressed, it can lead to more serious differential damage.
• Limited-Slip Clutch Wear: For models equipped with a limited-slip differential, wear on the clutch packs can lead to a loss of traction in slippery conditions or a chattering noise from the rear axle during tight turns. Regular fluid changes with the correct friction modifier can help prevent this.

Early diagnosis and repair of these issues are crucial to prevent more extensive and costly damage to the differential and driveline components.

Find a driveline shop on Repairius.