Awd Conversion Kit Drivetrain Modifications And Geometry

The allure of all-wheel drive (AWD) is undeniable. Superior traction, enhanced handling in adverse conditions, and a feeling of planted stability are just a few of the benefits that tempt many to convert their existing two-wheel-drive (2WD) vehicles. However, an AWD conversion is far more complex than simply bolting on a few parts. It's a significant undertaking that involves intricate drivetrain modifications and careful attention to geometry. This guide delves into the technical aspects of an AWD conversion, focusing on the drivetrain and suspension modifications required, as well as the critical geometry considerations that must be addressed.

Understanding the Challenges

Before diving into the specifics, it's crucial to understand the core challenges involved in converting a 2WD vehicle to AWD. The primary obstacle is that most 2WD vehicles are not designed to accommodate the necessary components of an AWD system. This means extensive modifications are required to the chassis, suspension, and drivetrain. Furthermore, the added weight and complexity of an AWD system can impact fuel economy and performance if not carefully planned and executed. A poorly executed conversion can negatively impact safety and vehicle dynamics.

Drivetrain Modifications: The Heart of the Conversion

The drivetrain is the most crucial aspect of an AWD conversion. It's responsible for transmitting power from the engine to all four wheels. Here's a breakdown of the key drivetrain components and modifications required:

Transfer Case: The Power Splitter

The transfer case is the component that splits engine power between the front and rear axles. Selecting the right transfer case is paramount. Considerations include:

Power Rating: The transfer case must be able to handle the engine's torque output. Overloading the transfer case can lead to premature failure.
Gear Ratio: The transfer case gear ratio influences the final drive ratio and overall performance. A lower gear ratio provides more torque for off-road applications, while a higher ratio improves fuel economy on the highway.
Type: Transfer cases come in various types, including part-time, full-time, and automatic. Part-time systems require manual engagement of the front axle, while full-time systems constantly drive all four wheels. Automatic systems use sensors to determine when to engage the front axle.
Mounting: The transfer case must be securely mounted to the vehicle's chassis. This often requires custom fabrication and welding.

Integrating the transfer case often involves significant modifications to the vehicle's transmission. In some cases, the existing transmission may need to be replaced with one compatible with a transfer case. This frequently involves modifying the transmission output shaft or replacing the entire unit. Custom adapters may also be needed to connect the transfer case to the transmission.

Front Differential and Axles: Delivering Power to the Front Wheels

Adding a front differential and axles is perhaps the most demanding part of the conversion. 2WD vehicles lack the necessary mounting points and clearance for these components. The following steps are typically required:

Subframe Modification or Replacement: The front subframe usually needs extensive modification or replacement to accommodate the front differential. This may involve cutting, welding, and reinforcing the existing subframe, or fabricating a completely new one.
Differential Selection: The front differential must be compatible with the transfer case and front axles. Gear ratio is a crucial consideration.
Axle Shafts: Custom axle shafts are often required to connect the differential to the front wheels. These shafts must be the correct length and strength to handle the engine's torque.
Hub and Knuckle Modifications: The front hubs and knuckles may need to be modified to accept the new axle shafts and accommodate the front drivetrain components.

Rear Drivetrain Considerations

While the front drivetrain receives the most attention during an AWD conversion, the rear drivetrain must also be addressed. Here are some key considerations:

Rear Differential Ratio: The rear differential ratio must match the front differential ratio to ensure proper AWD function. A mismatch in ratios can cause binding and damage to the drivetrain.
Rear Axle Strength: The existing rear axle may need to be upgraded to handle the increased power and stress of the AWD system.
Driveshaft: A new driveshaft is required to connect the transfer case to the rear differential. This driveshaft must be the correct length and have the appropriate U-joints.

Suspension Modifications and Geometry Considerations

Adding an AWD system significantly impacts the vehicle's suspension and geometry. The added weight of the drivetrain components can alter the vehicle's ride height, handling, and overall stability. Careful attention must be paid to these factors to ensure a safe and enjoyable driving experience.

Ride Height and Spring Rates

The added weight of the AWD components, particularly the front differential and axles, will lower the vehicle's front ride height. This can negatively affect handling and ground clearance. To compensate, the front springs may need to be replaced with stiffer springs or ride height adjustable coil-overs. The rear springs may also need to be adjusted to maintain a level ride height.

Wheel Alignment

Proper wheel alignment is critical after an AWD conversion. Changes in ride height and suspension geometry can significantly affect the vehicle's camber, caster, and toe. A professional wheel alignment is essential to ensure proper handling and tire wear. Common alignment issues to address include:

Camber: The angle of the wheel relative to the vertical axis. Negative camber can improve cornering grip, while positive camber can improve stability.
Caster: The angle of the steering axis relative to the vertical axis. Positive caster improves steering stability, while negative caster can make the steering more responsive.
Toe: The angle of the wheels relative to each other. Toe-in (wheels pointing slightly inward) can improve straight-line stability, while toe-out (wheels pointing slightly outward) can improve turn-in response.

Suspension Travel and Articulation

If the conversion is intended for off-road use, suspension travel and articulation are important considerations. The front suspension must have sufficient travel to absorb bumps and maintain contact with the ground. Limiting straps may be necessary to prevent over-extension of the suspension components. Sway bar disconnects can also improve articulation by allowing the suspension to move more freely.

Steering System Modifications

The steering system may also require modifications to accommodate the AWD system. The added weight and complexity of the front drivetrain can increase steering effort. A power steering upgrade may be necessary to provide adequate steering assist. Additionally, the steering linkage may need to be modified to clear the front differential and axles.

Conclusion

Converting a 2WD vehicle to AWD is a complex and challenging project that requires extensive technical knowledge and fabrication skills. It involves significant modifications to the drivetrain, suspension, and chassis. Careful attention must be paid to geometry, weight distribution, and component selection to ensure a safe and functional AWD system. While the process is undoubtedly demanding, the rewards of improved traction, enhanced handling, and increased versatility can make it a worthwhile endeavor for those willing to invest the time and effort. Always prioritize safety and consult with experienced professionals before undertaking such a project. Finally, thorough planning and meticulous execution are key to a successful AWD conversion.