Introduction
The Eaton Detroit Truetrac differential is a high-performance, limited-slip differential designed to improve traction and power delivery in rear-wheel-drive vehicles. It is particularly useful for applications where consistent cornering, dragstrip performance, and improved handling are critical. The installation process involves a series of precise mechanical steps, including gear and bearing replacement, backlash adjustment, and final assembly. This article outlines the key procedures and components involved in installing the Eaton Detroit Truetrac differential, based on a real-world example from a project car build. The details provided are drawn from a documented installation process involving an 8.8-inch rear axle housing, Yukon gears, and supporting components.
Key Components in the Installation
The installation of the Eaton Detroit Truetrac differential requires the integration of several key mechanical components, each of which contributes to the overall performance and durability of the system. These include:
- Yukon 4.10 Gear Set: This gear set is bolted onto the Truetrac differential and provides a more aggressive gear ratio than the stock setup. The 4.10 ratio is ideal for drag racing and performance driving, offering improved acceleration and engine RPM under load.
- Master Overhaul Kit: This kit includes all necessary bearings and seals for the rear axle assembly. Bearings and seals are replaced to ensure the differential operates smoothly and efficiently.
- 31-Spline Yukon Axles: These axles replace the stock shafts and provide significantly more strength. They are designed to handle higher torque and stress levels, making them suitable for performance applications.
- ABS Rings and Racing Wheel Studs: Before installing the new axles, ABS rings are pressed into place. Racing wheel studs, such as the 3-inch Racing Wheel Studs from Steeda Autosports, are also added to enhance the strength and reliability of the wheel assembly.
- Solid Billet Differential Cover: A reinforced cover is installed to prevent deflection under heavy acceleration. This cover is typically made of solid billet aluminum and includes preload bolts to further enhance structural integrity.
Each of these components plays a critical role in ensuring the Truetrac differential functions as intended and can withstand the demands of high-performance driving.
Step-by-Step Installation Process
The installation of the Eaton Detroit Truetrac differential is a complex but well-documented procedure. The following steps outline the key actions taken during the installation process:
1. Disassembly of the Existing Rear Axle
The first step in the installation is the removal of the existing rear axle components. This includes:
- Draining the Differential Fluid: Before any mechanical work can begin, all fluids must be drained from the rear differential housing.
- Removing the Exhaust System: The stock exhaust system, including the manifolds and midpipe, is removed to provide access to the rear axle.
- Removing the Driveshaft: The driveshaft is disconnected and removed to allow for the disassembly of the 8.8-inch rear housing.
- Removing the Stock Rear Cover and Components: The stock differential cover is removed, and the stock 3.55 gears are taken out. The existing bearings and races are also removed after a lengthy disassembly process.
This step is critical to gaining access to the internal components of the rear axle and preparing the housing for the new differential.
2. Preparing the Housing for the New Differential
Once the housing is empty, it must be cleaned and inspected for wear or damage. The next steps include:
- Installing the Master Overhaul Kit: All new bearings and seals are installed according to manufacturer specifications. This ensures that the differential will operate smoothly and without leaks.
- Bolting on the Yukon 4.10 Gear Set: The new gear set is bolted onto the Eaton Detroit Truetrac differential. This setup provides a more aggressive gear ratio, which is ideal for performance applications.
- Setting Backlash: Backlash is the amount of play between the gear teeth. In this installation, the backlash is set to 0.009 inch, a standard specification for proper gear meshing and performance. A small amount of paint is applied to the gear teeth to ensure they mesh correctly.
Setting the correct backlash is essential for ensuring the differential operates without vibration or noise and provides optimal power transfer.
3. Installing the New Axles and Components
With the differential and gear set in place, the new axles and supporting components are installed:
- Pressing in the ABS Rings: Before the new Yukon axles are installed, the ABS rings are pressed into place. These rings are part of the vehicle’s anti-lock braking system and must be precisely aligned.
- Installing the 31-Spline Yukon Axles: The new axles are slid into the differential housing and secured. These axles are significantly stronger than the stock units and are designed to handle the higher torque output of the modified engine.
- Adding Racing Wheel Studs: The 3-inch Racing Wheel Studs from Steeda Autosports are installed to enhance the strength and reliability of the wheel assembly. These studs are designed to withstand the stresses of high-performance driving.
These components work together to ensure the rear axle assembly is strong, reliable, and capable of handling the increased power output of the modified engine.
4. Final Assembly and Testing
The final steps in the installation involve reassembling the rear axle and ensuring that everything functions as intended:
- Bolting on the New Differential Cover: A solid billet differential cover is installed to provide additional strength and prevent deflection under heavy acceleration. This cover is typically made of aluminum and includes preload bolts to secure the main caps.
- Filling the Differential with Fluid: Once the cover is in place, the differential is filled with the appropriate fluid. In this case, Royal Purple 5W-20 synthetic oil is used to ensure proper lubrication of the moving parts.
- Testing and Verification: After installation, the vehicle is tested on both the dragstrip and the road course to verify that the new differential is functioning correctly. Adjustments are made as needed to ensure optimal performance.
This final phase is critical to ensuring that the installation is successful and that the vehicle performs as expected.
Benefits of the Eaton Detroit Truetrac Differential
The Eaton Detroit Truetrac differential offers several key benefits that make it an ideal choice for performance-oriented vehicles:
- Improved Traction and Power Delivery: As a limited-slip differential, the Truetrac ensures that power is distributed evenly between the wheels. This helps to reduce wheel spin and improve acceleration, especially on the dragstrip.
- Durability and Strength: The combination of the Truetrac differential, Yukon gears, and 31-spline axles provides a robust and durable rear axle assembly. This is essential for vehicles that are subjected to high-torque applications and aggressive driving.
- Compatibility with Performance Modifications: The Truetrac is designed to work with a wide range of performance modifications, including upgraded engines, exhaust systems, and suspension components. This makes it a versatile option for custom builds.
- Enhanced Handling and Stability: The limited-slip nature of the Truetrac helps to improve cornering performance by preventing one wheel from spinning while the other has traction. This results in better handling and more predictable behavior during high-speed maneuvers.
These benefits make the Eaton Detroit Truetrac differential a popular choice among performance enthusiasts and racers.
Considerations for Installation
While the Eaton Detroit Truetrac differential offers numerous advantages, there are several considerations to keep in mind during the installation process:
- Technical Skill and Experience: Installing a rear differential is a complex task that requires a solid understanding of mechanical systems. It is recommended that only experienced technicians or DIY enthusiasts with the necessary tools and knowledge attempt this installation.
- Compatibility with Vehicle Components: The Truetrac must be compatible with the vehicle’s existing rear axle housing, gear ratio, and other components. In some cases, modifications may be necessary to ensure a proper fit and function.
- Lubrication and Maintenance: The differential requires regular maintenance, including fluid changes and inspections. Using high-quality synthetic oils, such as Royal Purple 5W-20, can help extend the life of the components and ensure smooth operation.
- Driving Conditions and Use: The Truetrac is best suited for performance applications, such as drag racing and road courses. While it can be used in daily driving scenarios, it is not ideal for all driving conditions and may require adjustments to optimize performance.
These factors should be carefully evaluated to ensure that the installation meets the specific needs of the vehicle and its intended use.
Conclusion
The installation of the Eaton Detroit Truetrac differential is a detailed and precise process that involves the replacement of multiple components, including gears, bearings, axles, and the differential cover. When installed correctly, the Truetrac offers significant improvements in traction, power delivery, and overall performance. It is particularly well-suited for vehicles that are modified for drag racing, road courses, or other high-performance applications. The use of supporting components, such as the Yukon 4.10 gear set, 31-spline axles, and solid billet differential cover, ensures that the rear axle assembly is both strong and reliable. While the installation process requires technical expertise and experience, the benefits of the Truetrac make it a worthwhile investment for performance enthusiasts seeking to enhance their vehicle’s capabilities.