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When it comes to modifying your BMW 335i, one of the most effective upgrades for performance enthusiasts is the 335i diff retrofit Ford. This swap involves replacing the stock BMW differential with a more robust and durable Ford 8.8 differential. The Ford 8.8 differential is known for its strength and reliability, making it an excellent choice for handling increased power and torque in the BMW 135i, 335i, and M3 models.
In this comprehensive guide, we’ll cover everything you need to know about the 335i diff retrofit Ford, including the benefits, required parts, installation process, and frequently asked questions. Whether you’re looking to improve the durability of your drivetrain or enhance your car’s performance, this guide will provide all the information you need.
Why Choose a 335i Diff Retrofit Ford?
The 335i diff retrofit Ford is a popular upgrade among car enthusiasts who want to enhance the reliability and performance of their vehicle. The stock BMW differential, while adequate for normal driving, may struggle under the pressure of high-performance applications, especially if you’ve increased your car’s power output.
Here are some key reasons why people opt for the 335i diff retrofit Ford:
1. Strength and Durability:
The Ford 8.8 differential is built to handle more torque and power compared to the stock BMW differential. This makes it an ideal option for those who have modified their 335i for increased horsepower or who participate in high-performance driving events.
2. Cost-Effective Solution:
A 335i diff retrofit Ford is often more cost-effective than upgrading to a high-performance aftermarket BMW differential. The Ford 8.8 differential is widely available, and the parts needed for the swap can be sourced at a reasonable price.
3. Customization Options:
The 335i diff retrofit Ford allows for greater customization in terms of gear ratios and locking differentials. This gives you more control over how your car performs, especially in racing or high-speed driving scenarios.
Required Parts for a 335i Diff Retrofit Ford:
Before starting the 335i diff retrofit Ford, you’ll need to gather all the necessary parts for the swap. Here’s a list of the key components required:
1. Ford 8.8 Differential:
The Ford 8.8 differential is the core of this retrofit. Make sure to select the right gear ratio based on your driving preferences and performance goals.
2. Diff Adapter Brackets:
These brackets are used to mount the Ford 8.8 differential onto your BMW’s subframe. They are crucial for ensuring a secure fit.
3. Single Piece Driveshaft:
A single piece driveshaft is recommended for improved reliability and smoother power delivery. This will connect the Ford 8.8 differential to your BMW’s transmission.
4. Billet Axle Stubs:
Billet axle stubs are required to mate the Ford 8.8 differential with your BMW’s axles. These stubs are typically custom-made to ensure a perfect fit.
5. Carbon Fiber or Steel Driveshaft Option:
Some enthusiasts opt for a carbon fiber driveshaft for reduced weight and increased performance. However, a steel driveshaft is also a solid option for durability and cost-effectiveness.
Installation Process for a 335i Diff Retrofit Ford:
Installing a 335i diff retrofit Ford is a technical process that requires precision and mechanical knowledge. Here’s a general overview of the steps involved:
Step 1: Remove the Stock BMW Differential
Begin by safely lifting the vehicle and removing the stock BMW differential. This will involve disconnecting the driveshaft, axles, and any supporting brackets.
Step 2: Install Diff Adapter Brackets
Next, install the diff adapter brackets to the BMW subframe. These brackets are designed to hold the Ford 8.8 differential in place and ensure proper alignment.
Step 3: Mount the Ford 8.8 Differential
Carefully mount the Ford 8.8 differential onto the adapter brackets. Ensure that all bolts are tightened to the manufacturer’s specifications.
Step 4: Install the Driveshaft
Connect the single-piece driveshaft to the Ford 8.8 differential and your BMW’s transmission. Make sure the driveshaft is properly aligned to avoid vibrations during driving.
Step 5: Attach Billet Axle Stubs
Install the billet axle stubs to connect the Ford 8.8 differential with your BMW’s axles. This step is crucial for transferring power from the differential to the wheels.
Step 6: Final Checks
After all components are installed, double-check all connections and bolts. Ensure that the differential is properly aligned and secured. Perform a test drive to ensure that everything is functioning correctly.
Benefits of a Single Piece Driveshaft in a 335i Diff Retrofit Ford:
The 335i diff retrofit Ford often includes the installation of a single-piece driveshaft, which offers several benefits:
- Improved Durability: A single-piece driveshaft reduces the risk of failure under high-performance conditions.
- Smoother Power Delivery: With fewer moving parts, a single-piece driveshaft ensures smoother power transfer from the engine to the wheels.
- Reduced Weight: If you opt for a carbon fiber driveshaft, you can significantly reduce the weight of the drivetrain, leading to better acceleration and handling.
Fine-Tuning the 335i Diff Retrofit Ford:
When undertaking the 335i diff retrofit Ford, fine-tuning is crucial for achieving optimal performance and reliability. One important aspect is adjusting the differential’s pinion angle. This angle affects the alignment between the driveshaft and the differential, which can influence vibrations and drivetrain efficiency.
Proper adjustment ensures that the driveshaft operates smoothly and minimizes wear on the components. To achieve this, you may need to use adjustable control arms or shims to fine-tune the pinion angle to the manufacturer’s specifications.
Compatibility Considerations:
Another crucial factor in the 335i diff retrofit Ford is ensuring compatibility between the Ford 8.8 differential and the BMW chassis. The Ford differential’s mounting points and dimensions may differ from the stock BMW setup, requiring precise modifications.
Some enthusiasts choose to use custom-built brackets or modified subframes to accommodate the new differential. It’s essential to carefully measure and verify all dimensions before proceeding with the installation to avoid alignment issues or potential clearance problems.
Impact on Vehicle Dynamics:
Swapping to a Ford 8.8 differential can significantly impact your vehicle’s dynamics. The weight distribution and handling characteristics may change due to the difference in the differential’s size and weight. This can affect how the car behaves during acceleration, cornering, and braking.
To maintain balanced handling, you might need to adjust suspension settings or upgrade other components, such as shocks and springs, to match the new drivetrain setup. Understanding these changes will help you optimize your vehicle’s performance and driving experience.
Long-Term Maintenance and Upkeep:
The 335i diff retrofit Ford involves long-term maintenance considerations. Regularly inspecting and servicing the Ford 8.8 differential is essential to ensure its longevity and reliable performance. This includes checking the differential fluid levels, looking for any signs of leaks or wear, and replacing fluids as recommended by the manufacturer.
Additionally, monitor the condition of the driveshaft and axle stubs, as these components are subject to wear over time. Proper maintenance will help prevent issues and keep your vehicle performing at its best for years to come.
Customization and Upgrading Options:
The 335i diff retrofit Ford provides opportunities for additional customization that can further enhance your vehicle’s performance. Beyond just swapping the differential, you can choose different types of gear ratios to better match your driving needs.
For instance, opting for a lower gear ratio can improve acceleration and responsiveness, while a higher gear ratio may benefit highway cruising by reducing engine RPMs.
Additionally, some enthusiasts install aftermarket limited-slip differentials within the Ford 8.8 housing to improve traction and handling, especially in high-performance or off-road scenarios.
Integration with Vehicle Electronics:
Integrating the 335i diff retrofit Ford with your vehicle’s electronics is another consideration that may not be immediately obvious. Modern BMWs come equipped with sophisticated electronics that monitor and adjust various aspects of the drivetrain.
After the retrofit, it’s crucial to recalibrate these systems to ensure they work harmoniously with the new differential. This may involve adjusting settings in the vehicle’s ECU or using diagnostic tools to align sensor readings with the new drivetrain configuration.
Ensuring that your vehicle’s electronics are correctly integrated can prevent issues such as erroneous warning lights or malfunctioning traction control systems.
Noise, Vibration, and Harshness (NVH) Management:
One potential downside of the 335i diff retrofit Ford is an increase in noise, vibration, and harshness (NVH) levels, which can be noticeable compared to the stock differential. The Ford 8.8 differential, being larger and heavier, might produce more noise or vibrations, particularly if it’s not installed with high-quality components.
To manage NVH, consider using vibration-dampening mounts or isolators designed to reduce the transfer of vibrations from the differential to the chassis. Additionally, high-quality lubrication and regular maintenance can help mitigate excessive noise and vibrations.
Legal And Regulatory Considerations:
Before proceeding with the 335i diff retrofit Ford, it’s essential to be aware of any legal and regulatory considerations. In some regions, modifications to a vehicle’s drivetrain may require specific inspections or certifications to ensure compliance with local emissions and safety regulations.
This could involve getting the retrofit inspected by a certified mechanic or emissions specialist. Ensuring that your modification adheres to local laws not only helps avoid potential fines but also ensures that your vehicle remains roadworthy and safe for everyday use.
Conclusion:
The 335i diff retrofit Ford is an excellent upgrade for anyone looking to improve the durability, strength, and performance of their BMW 335i. With the right parts, including the Ford 8.8 differential, diff adapter brackets, billet axle stubs, and a single-piece driveshaft, this retrofit can transform your vehicle’s drivetrain into a more reliable and powerful system.
Whether you’re a track enthusiast or just someone who wants a stronger differential for daily driving, the 335i diff retrofit Ford offers a cost-effective and customizable solution for maximizing your car’s potential.
