2018 Subaru Forester Transmission & Axle Gear Ratios

Transmission gear ratios

The 2018 Subaru Forester offers two transmission options: a 6-speed manual and a Lineartronic Continuously Variable Transmission (CVT).

6-Speed Manual Transmission

Lineartronic CVT Transmission

Available axle ratios

The 2018 Subaru Forester comes with different axle ratios depending on the transmission and trim level.

How to identify your axle ratio

Unlike some domestic brands, Subaru does not typically use RPO codes on a door jamb sticker to identify axle ratios. For the 2018 Forester, the axle ratio is primarily determined by the transmission type and engine.

• Manual Transmission: All 2.5i models with the 6-speed manual transmission come with a 4.44 final drive ratio.
• CVT (2.5i models): All 2.5i models equipped with the Lineartronic CVT have a 3.70 final drive ratio.
• CVT (2.0XT models): The 2.0XT models, with their turbocharged engine, utilize a 4.11 final drive ratio with the Lineartronic CVT.

If you are unsure, your owner's manual or a Subaru dealership can provide definitive information based on your VIN.

Towing vs MPG impact

The axle ratio plays a significant role in determining a vehicle's balance between towing capability and fuel economy.

• Numerically Higher Ratio (e.g., 4.44): A higher numerical axle ratio means the engine will complete more revolutions for every rotation of the wheels. This provides greater torque multiplication, which is beneficial for towing heavy loads, accelerating quickly, and driving in hilly terrain. However, the trade-off is often reduced fuel efficiency at highway speeds, as the engine will be revving higher to maintain a given road speed.

• Numerically Lower Ratio (e.g., 3.70): A lower numerical axle ratio means fewer engine revolutions per wheel rotation. This results in the engine working less at higher speeds, leading to improved fuel economy, especially on the highway. The downside is typically reduced towing capacity and slower acceleration, as there's less torque multiplication to get the vehicle moving or pull heavy loads.

The 2018 Subaru Forester's various ratios are chosen by the factory to best suit the intended use of each powertrain combination. The 2.0XT models with their more powerful engine and 4.11 ratio are designed to provide a more spirited driving experience, while still offering decent fuel economy due to the efficiency of the CVT.

Common issues

While the Subaru Forester is generally known for its reliability, like any mechanical component, the driveline can experience certain issues over time.

• CVT Reliability: While Subaru's Lineartronic CVT has improved significantly, some earlier models and isolated cases in later models can experience issues such as shuddering, slipping, or unusual noises. Proper maintenance, including regular fluid changes, is crucial for CVT longevity.

• Rear Differential Whine: Some owners may report a whining noise from the rear differential, particularly under acceleration or deceleration. This can be caused by worn bearings, improperly set gear mesh, or even low differential fluid. Addressing this early is important to prevent more significant damage.

• Axle Seals: Leaking axle seals can occur, leading to a loss of differential fluid. This can be identified by fluid stains around the differential or on the inner wheel. Prompt replacement of the seals is necessary to prevent differential damage.

Find a driveline shop on Repairius.