How does a Subaru transfer case work?

The Subaru transfer case is a critical component in the all-wheel-drive (AWD) system of Subaru vehicles. It plays a crucial role in distributing power from the engine to all four wheels, providing enhanced traction and stability on various road conditions. In this article, we'll delve into the inner workings of a Subaru transfer case and understand how it contributes to the brand's renowned all-wheel-drive performance.

What is a Transfer Case?

A transfer case is a mechanical device found in four-wheel-drive (4WD) and all-wheel-drive (AWD) vehicles. Its primary function is to transfer power from the transmission to the front and rear axles, allowing the vehicle to operate in different drive modes, such as two-wheel-drive (2WD), four-wheel-drive (4WD), or all-wheel-drive (AWD).

Subaru's Symmetrical All-Wheel-Drive System

Subaru's AWD system is known as Symmetrical All-Wheel-Drive, and it is a key feature that sets the brand apart from its competitors. The Subaru transfer case is an integral part of this system, which is designed to provide a balanced and efficient power distribution to all four wheels. The Symmetrical layout of the drivetrain components, including the transfer case, helps to maintain an even weight distribution, improving handling and stability.

How the Subaru Transfer Case Works

The Subaru transfer case is responsible for distributing power from the transmission to the front and rear axles. It typically features a planetary gear set, which allows the transfer case to vary the amount of power sent to the front and rear wheels, depending on driving conditions and the selected drive mode.

• Power Input: The transfer case receives power from the transmission, which is connected to the engine.


• Power Distribution: The transfer case then splits the power between the front and rear axles, typically in a 50/50 ratio for normal driving conditions.


• Differential Gears: The transfer case also contains differential gears, which allow the front and rear wheels to rotate at different speeds, enabling the vehicle to turn corners smoothly.


• Drive Mode Selection: Many Subaru models allow the driver to select different drive modes, such as 2WD, 4WD, or AWD, which the transfer case then adjusts to provide the appropriate power distribution.

The Subaru transfer case is designed to provide seamless and responsive power delivery, ensuring that the vehicle maintains optimal traction and stability in a wide range of driving conditions, from dry pavement to slippery surfaces.

Benefits of the Subaru Transfer Case

The Subaru transfer case offers several key benefits that contribute to the brand's renowned all-wheel-drive performance:

• Improved Traction: By distributing power to all four wheels, the transfer case enhances traction and grip, especially in challenging road conditions such as snow, ice, or mud.


• Enhanced Stability: The balanced power distribution provided by the transfer case helps to improve the vehicle's stability and handling, particularly during cornering and high-speed maneuvers.


• Versatility: The ability to select different drive modes allows Subaru owners to optimize their vehicle's performance for various driving scenarios, from efficient two-wheel-drive for everyday commuting to rugged four-wheel-drive for off-road adventures.


• Durability: Subaru's transfer cases are engineered to be robust and reliable, ensuring long-lasting performance and minimal maintenance requirements.

In conclusion, the Subaru transfer case is a crucial component that enables the brand's renowned Symmetrical All-Wheel-Drive system. By distributing power efficiently and seamlessly to all four wheels, the transfer case plays a vital role in delivering the exceptional traction, stability, and versatility that Subaru vehicles are known for.

Does Subaru use a transfer case?

Yes, Subarus have a transfer case, but it is integrated directly into the transmission, unlike many other vehicles where it is a separate component. This integrated design, often referred to as a center differential or AWD unit, distributes power from the transmission to the front and rear axles.
 

• Integrated design: Subaru's design combines the transmission, center differential (transfer case), and front differential into a single unit. This helps centralize weight for better handling. 
• Automatic transmissions: In automatic transmissions, the system often uses an electronic hydraulic transfer clutch to manage torque distribution between the front and rear wheels. 
• Manual transmissions: Manual transmissions typically use a viscous-coupling center differential that is a sealed and non-serviceable unit within the transmission assembly. 
• Maintenance: Because the transfer case is integrated into the transmission, it often shares the same fluid, and servicing it may involve changing the transmission fluid. However, some parts, like the viscous coupler in manual transmissions, are not designed to be serviced separately. 

How does an AWD transfer case work?

Configuration. Four-wheel drive high range. Power is distributed to both the front and rear axles providing improved traction on slippery surfaces or loose terrain.

Is the Subaru Forester permanent 4WD?

So you can rely on all-new Forester's advanced safety features to give you unparalleled peace of mind at all times. Our renowned permanent Symmetrical All-Wheel Drive system ensures Subarus are sure-footed in all conditions.

How does the transfer case work?

A transfer case works by splitting power from the transmission and sending it to both the front and rear axles, allowing a vehicle to switch between two-wheel drive (2WD) and four-wheel drive (4WD) modes. It uses a system of gears, chains, and clutches to control how the engine's power is distributed, with options to select different modes like 4WD High for better traction at speed or 4WD Low for increased torque for off-road driving.
 
This video explains the operation of a transfer case in four-wheel drive systems: 57sCountermanYouTube · Jul 8, 2024
How it distributes power

• Input Shaft: Receives power from the transmission's output shaft. 
• Power Distribution: The transfer case's gears and/or chain drive then split this power and send it to two output shafts: one for the front axle and one for the rear. 
• Mode Selection: A driver or the vehicle's computer can select the mode, which engages or disengages different internal components to control which wheels receive power. 

Common modes

• 2WD (Two-Wheel Drive): Power is sent to only one axle, usually the rear, for normal driving conditions and better fuel efficiency. 
• 4WD High: Power is sent to both the front and rear axles to provide better traction on slippery surfaces like ice, snow, or gravel. 
• 4WD Low: In this mode, a reduction gear provides significantly more torque at lower speeds, which is ideal for tackling steep hills, pulling heavy loads, or navigating rough off-road terrain. 

This video demonstrates the internal components of a transfer case and how they work together: 58sPrecision TransmissionYouTube · Sep 13, 2021
Other functions

• Synchronization: The transfer case synchronizes the rotation of the front and rear wheels to prevent binding and strain on the drivetrain. 
• Adaptive Control: Some modern all-wheel drive (AWD) systems have transfer cases that can sense a loss of traction and automatically distribute power where it's needed without driver input.