2019 GMC Acadia: Transmission & Axle Gear Ratios

Transmission Gear Ratios

The 2019 GMC Acadia was offered with two different automatic transmissions, a 6-speed and a 9-speed, depending on the engine choice.

6-Speed Automatic (6T50)

This transmission was paired with the base 2.5L 4-cylinder engine.

9-Speed Automatic (9T65)

This transmission was standard with the optional 3.6L V6 engine, providing a wider spread of ratios to balance acceleration and fuel economy.

Available Axle Ratios

Unlike trucks and rear-wheel-drive vehicles, modern front-wheel-drive and all-wheel-drive crossovers like the Acadia have a single final drive ratio that is integrated into the transaxle. This ratio is not typically offered in multiple options for a given powertrain combination. Instead, the final drive ratio is optimized from the factory for the best balance of performance and efficiency for that specific engine and transmission pairing.

For the 2019 Acadia, the final drive ratios are fixed based on the powertrain configuration.

Note: The effective final drive ratio in AWD models can be influenced by the twin-clutch AWD system, but the primary axle ratio remains 3.16 for all V6 models.

How to Identify Your Axle Ratio

Since the axle ratio on the 2019 Acadia is tied directly to the engine, identifying your engine is the easiest way to know your ratio. However, you can also confirm it by looking for the Service Parts Identification (RPO) sticker.

• Door Jamb RPO Sticker: Open the driver's side door and look for a silver sticker on the door jamb or inside the glove box. This sticker lists all the three-character Regular Production Option (RPO) codes for your vehicle. Look for the codes listed in the table above (F17 or GW5) to confirm your axle ratio.
• VIN Decoder: A VIN decoder service can provide a build sheet for your specific vehicle, which will include the engine, transmission, and final drive ratio information.

Given the Acadia's transaxle design, there is no external "axle tag" on the differential housing as you would find on a traditional solid-axle truck.

Towing vs. MPG Impact

The relationship between gear ratios and vehicle performance is a balance of trade-offs. The 2019 Acadia's powertrains were engineered to provide an optimal blend from the factory.

• Numerically Higher Ratio (e.g., 3.80 on the 2.5L): A "shorter" gear ratio like this allows the engine to spin more quickly relative to wheel speed. This provides better leverage and improved acceleration from a stop, which is helpful for getting the vehicle moving with a less powerful engine. The trade-off is that the engine will run at a higher RPM on the highway, which can negatively impact fuel economy.

• Numerically Lower Ratio (e.g., 3.16 on the 3.6L V6): A "taller" gear ratio means the engine spins slower for a given wheel speed. This is ideal for highway cruising, as the lower engine RPMs reduce fuel consumption and engine noise. With the V6 engine's ample torque, a taller ratio can be used without making the vehicle feel sluggish. When equipped with the V92 Trailering Package, the 9-speed transmission's very low first gear compensates for the taller final drive ratio, providing the necessary torque multiplication for towing up to its 4,000-pound rating.

Common Issues

The powertrain components in the 2019 Acadia are generally considered reliable, but a few issues have been noted by owners.

• 6-Speed (6T50) Transmission: Some owners have reported issues with harsh shifting or a "shudder" feeling, which can sometimes be traced to a failing torque converter or require a fluid flush and software update.
• 9-Speed (9T65) Transmission: While generally smooth, some early models experienced shift quality complaints that were often addressed with transmission control module (TCM) reprogramming by the dealer. It is sensitive to using the correct specification of transmission fluid.
• AWD System: The twin-clutch AWD system available on some models (standard on All-Terrain) can develop issues with the rear differential clutch module, sometimes presenting as a "Service AWD" message on the dash. This is not an axle ratio problem but a failure of the electronic control components.

If you are experiencing a whining noise that changes with vehicle speed, clunking during shifts, or vibrations, it could indicate a problem with the transmission or final drive components. It's important to have these symptoms diagnosed by a qualified technician.

Find a driveline shop on Repairius.