The Eaton Detroit Truetrac differential is a helical-gear limited-slip differential designed to maximize traction and driving performance across a wide range of vehicle applications. This article provides a detailed overview of the installation process, application specifics, and technical considerations based on verified information from official documentation and application guides. The discussion is limited to the content provided in the source materials and does not include speculative or external data.
Overview of the Detroit Truetrac Differential
The Eaton Detroit Truetrac differential is a high-performance traction solution suitable for both street and performance applications. Unlike traditional limited-slip differentials that rely on clutch packs or mechanical locking mechanisms, the Truetrac uses a helical gear design to distribute torque between the drive wheels. This design allows for smoother operation and reduced wear, making it ideal for high-torque and high-performance environments.
Key features of the Detroit Truetrac include:
- Helical-gear technology: Ensures consistent torque transfer and improved handling.
- Versatility: Compatible with a wide range of vehicle models, including trucks, SUVs, and performance cars.
- Durability: Engineered to withstand the rigors of both street and track use.
- Minimal maintenance: No clutch or friction plate replacements required compared to traditional limited-slip units.
The Truetrac is offered for various rear-axle configurations, including 8.8-inch, 9.25-inch, and 9.5-inch ring gear applications. Installation compatibility is dependent on axle spline count, gear ratio, and vehicle model year.
Installation Considerations and Technical Specifications
Installation of the Detroit Truetrac differential involves a series of precise mechanical and assembly steps. According to the source material, the process includes disassembly of the existing rear differential, installation of the Truetrac unit, and reassembly with appropriate shimming and oil specifications. Below are key technical considerations based on the provided documentation.
1. Disassembly and Preparation
Prior to installing the Truetrac, the existing differential assembly must be removed. As detailed in the application guide and installation notes, the following steps are generally involved:
- Exhaust and driveshaft removal: Access to the rear differential is typically gained by removing the exhaust system and driveshaft.
- Axle housing disassembly: The rear cover is removed to access internal components, including gears, bearings, and the existing differential unit.
- Gear and bearing removal: Stock bearings and races are removed to prepare the housing for the new Truetrac assembly.
A complete overhaul kit, including new bearings and seals, is typically required to ensure a successful installation. These kits are available for various applications, including 8.8-inch and 9.25-inch housing configurations.
2. Truetrac Installation and Gear Meshing
Once the housing is prepared, the Truetrac unit is installed along with new bearings. The gear mesh must be verified using a backlash measurement and tooth contact pattern.
- Backlash measurement: A typical backlash range is between 0.005 and 0.010 inches. The example provided in the source material shows a backlash of 0.009 inch.
- Tooth contact pattern: The contact pattern must be checked using gear paint. An ideal pattern is evenly spread over the tooth profile with concentration near the toe end.
- Adjustments: If the contact pattern indicates misalignment (e.g., heel or toe contact), the ring gear position must be adjusted by adding or removing shims to correct the backlash.
3. Compatibility and Model-Specific Notes
The Truetrac is available for a wide range of applications, including:
- Ford Mustang (S550): Compatible with 2015–current model years, including 2.3L EcoBoost, V6/3.7L, and V8/5.0L engines. Requires a 34-spline configuration and 8.8-inch ring gear.
- GM 1500 trucks: Available for 2014–current model years with 3.42 and 3.73 gear ratios. Requires a 9.5-inch or 9.76-inch ring gear and a 33-spline configuration.
- Ram trucks: Compatible with 2011–current 1/2-ton models, featuring a 9.25-inch ring gear and 31-spline configuration.
- Toyota and Jeep applications: Specific models such as the Wrangler (JL) and Gladiator (JT) are supported with ELocker configurations and appropriate spline counts.
Additional model-specific notes include:
- Oil drain plug modification: In some GM and Ram applications, the factory drain plug may require shortening by approximately 1/8 inch to maintain clearance with the differential housing.
- Pressure angle requirements: Certain units are designed for axles cut with 45-degree pressure angles.
- Gear set compatibility: Thin or thick ring gears may require specific gear sets (e.g., 3.73 thin gear sets).
Shimming and Adjustment Procedures
Proper shimming is critical for ensuring correct gear mesh and minimizing wear. The following adjustments are outlined in the source material:
- Ideal contact pattern: The gear contact should be evenly spread with concentration near the toe end of the tooth.
- Competition contact: If the pattern is concentrated near the toe, it may indicate a need for tighter backlash.
- Heel contact: Indicates the ring gear is too far from the pinion; adjust by moving the ring gear closer to the pinion.
- Toe contact: Indicates the ring gear is too far from the pinion; adjust by moving the ring gear away from the pinion.
- High contact: Indicates the pinion is too deep; adjust by adding a pinion shim.
- Low contact: Indicates the pinion is too shallow; adjust by removing a pinion shim.
These adjustments are made using standard shimming tools and require careful measurement to ensure the gear teeth are properly aligned.
Oil Selection and Maintenance
Eaton recommends using the correct lubricant for the Truetrac differential. The type of oil may vary based on the vehicle's intended use (e.g., street driving, drag racing, or road course performance). The source material emphasizes the importance of selecting the appropriate viscosity and additive package to ensure long-term reliability.
- Viscosity recommendations: Typically 75W-90 or 80W-90 gear oil.
- Additives: Synthetic or semi-synthetic oils with limited-slip additive packages are recommended for optimal performance.
The oil must be filled to the proper level after installation, and the drain plug must be reinstalled to prevent leaks.
Service and Repair Considerations
Eaton provides service kits for the Detroit Truetrac, which include components such as bearings, seals, and shims. These kits are available for various differential sizes and applications. Service procedures are generally straightforward but require adherence to manufacturer specifications to ensure correct assembly.
- Service kits: Available for 7.5", 7.625", 8.2", and other ring gear sizes.
- Preload kits: Offered in multiple torque settings (200#, 400#, 800#) to accommodate different performance requirements.
- Component compatibility: Service kits must be selected based on the specific model year, gear ratio, and axle configuration.
Warranty and Support
Eaton offers a standard warranty for the Detroit Truetrac differential, though the exact terms are not specified in the provided source material. Users are directed to the official website (www.EatonPerformance.com) for detailed warranty and support information.
The documentation also includes frequently asked questions (FAQs) regarding installation, break-in procedures, and performance expectations. Users are encouraged to consult these resources to ensure proper setup and operation.
Practical Applications and User Feedback
The Truetrac has been successfully installed in a variety of performance builds, including drag racing applications and road course setups. As noted in the source material, one example involved the installation of a Truetrac into an 8.8-inch rear end of a 2003 Mustang Mach 1. The unit was paired with a 4.10 gear set and significantly improved traction on both the dragstrip and road course.
The installation was performed in conjunction with a full differential overhaul, including new bearings, seals, and a high-performance gear set. The result was a durable and reliable traction solution that enhanced the vehicle's performance without sacrificing drivability.
Conclusion
The Eaton Detroit Truetrac differential offers a robust and versatile traction solution for a wide range of performance and enthusiast applications. Its helical-gear design provides consistent torque transfer, reduced wear, and improved handling characteristics compared to traditional limited-slip differentials. Installation requires careful attention to gear mesh, backlash, and shimming procedures to ensure optimal performance and longevity.
When selecting a Truetrac unit, users must consider factors such as axle spline count, gear ratio, and model year compatibility. Additional considerations include oil selection, clearance verification, and the use of appropriate service kits for maintenance or repair.
For users seeking a high-performance differential that balances traction, durability, and ease of maintenance, the Eaton Detroit Truetrac is a compelling option. By following manufacturer guidelines and leveraging the detailed application information provided in the source materials, installers can achieve a reliable and high-performing drivetrain setup.