The Dodge 68RFE transmission is a six-speed automatic transmission designed for heavy-duty use in Dodge and Ram trucks, primarily paired with Cummins diesel engines. Known for its combination of strength, performance, and adaptability, the 68RFE has become a staple in the world of diesel trucks since its introduction. Understanding its history offers insights into the engineering advancements and challenges that shaped this transmission’s development.
Early Development and Introduction
The 68RFE transmission was introduced by Dodge in 2007, specifically designed to handle the demands of the powerful 6.7L Cummins turbo diesel engine in heavy-duty Ram 2500, 3500, 4500, and 5500 models. At the time, Dodge needed a transmission that could not only withstand high torque outputs but also deliver smooth shifting and enhanced towing capabilities to meet the needs of demanding truck owners.
Key Goals of the 68RFE’s Design
Dodge engineers aimed to create a transmission that could:
- Handle the immense torque generated by the 6.7L Cummins engine (initially rated at 650 lb-ft).
- Provide efficient operation for both everyday driving and extreme towing conditions.
- Meet increasingly stringent emissions standards.
- Offer improved fuel economy and a smoother driving experience compared to earlier transmissions.
To achieve these goals, the 68RFE featured a robust design with innovative features tailored to heavy-duty applications.
Features of the 68RFE Transmission
The 68RFE is an electronically controlled, six-speed automatic transmission with a range of features that made it suitable for the high-performance demands of diesel trucks:
- Torque Capacity: The 68RFE was designed to handle up to 650 lb-ft of torque in its initial configurations, though later versions supported even higher outputs as Cummins engines became more powerful.
- Gear Ratios: With six forward gears, the 68RFE offered a wider range of ratios for better towing performance, smoother acceleration, and improved fuel efficiency.
- 1st Gear: 3.23:1
- 2nd Gear: 1.84:1
- 3rd Gear: 1.41:1
- 4th Gear: 1.00:1
- 5th Gear: 0.82:1
- 6th Gear: 0.63:1
- Reverse: 4.44:1
- Hydraulic and Electronic Control: The transmission used a combination of hydraulic controls and electronic solenoids for precise shifting. Dodge incorporated adaptive shift logic, allowing the transmission to adjust its behavior based on driving conditions and load.
- Dual Overdrive Gears: The inclusion of two overdrive gears (5th and 6th) improved highway fuel economy and reduced engine wear during long-distance travel.
- Heavy-Duty Components: Reinforced internal components, such as larger clutch packs and planetary gears, ensured the 68RFE could handle the stresses of heavy loads and frequent towing.
Improvements Over Previous Transmissions
The 68RFE replaced the 48RE, a four-speed automatic transmission used in earlier Dodge Ram trucks. While the 48RE was reliable, it lacked the sophistication and efficiency demanded by modern diesel engines and truck owners. Key improvements included:
- Increased Durability: The 68RFE was built with more robust components to withstand the higher torque outputs of the 6.7L Cummins engine.
- More Gears: The transition from four to six gears provided smoother shifting and better performance across a broader range of speeds and loads.
- Advanced Control Systems: Electronic controls allowed for more precise operation and adaptability, reducing wear and improving longevity.
Challenges and Criticism
Despite its advancements, the 68RFE was not without its challenges. Some truck owners experienced issues, particularly in high-performance or extreme towing scenarios. Common complaints included:
- Overheating: Prolonged towing under heavy loads could lead to transmission overheating, especially without auxiliary cooling systems.
- Torque Converter Failures: The factory torque converter sometimes struggled under high stress, leading to slippage or early failure.
- Clutch Wear: Excessive clutch wear was reported in trucks that frequently operated at or near their maximum towing capacities.
- Programming Limitations: Some drivers criticized the transmission’s shift programming, citing delays or less-than-smooth transitions between gears, especially under heavy acceleration.
To address these issues, Dodge and Ram offered software updates and improvements in subsequent model years, and the aftermarket community developed numerous upgrades for the 68RFE.
Upgrades and Modifications
Recognizing the demand for greater durability and performance, many aftermarket companies began offering upgrades for the 68RFE transmission. Popular modifications include:
- Heavy-Duty Torque Converters: Upgraded torque converters improved reliability and reduced slippage under heavy loads.
- Performance Clutches: Aftermarket clutch packs enhanced durability for high-torque applications.
- Valve Body Upgrades: Improved valve bodies increased hydraulic flow and shift precision.
- Transmission Coolers: Enhanced cooling systems prevented overheating during extreme towing or hauling.
These upgrades allowed owners to push their trucks beyond factory specifications, making the 68RFE a favorite among diesel enthusiasts.
Evolution and Legacy
As Cummins engines grew more powerful, the 68RFE faced increasing pressure to meet the demands of modern diesel trucks. By the late 2010s, Ram began transitioning to the Aisin AS69RC transmission in many high-output Cummins models, which offered even greater torque capacity and durability for commercial-grade applications.
However, the 68RFE remains a cornerstone in Dodge/Ram’s transmission lineup and continues to be used in many trucks, particularly those with standard-output Cummins engines. Its combination of affordability, versatility, and widespread aftermarket support has solidified its place in the heavy-duty truck market.
The Dodge 68RFE transmission represents a significant chapter in the evolution of heavy-duty truck performance. Designed to meet the demands of the 6.7L Cummins engine, it offered improved durability, efficiency, and adaptability over its predecessors. While not without its challenges, the 68RFE has proven itself a capable workhorse, earning a loyal following among truck owners and diesel enthusiasts alike. Its legacy as a reliable, high-performance transmission continues to be celebrated, and with the right care and upgrades, it remains a formidable option for towing, hauling, and everyday driving. Action Transmission can rebuild 68RFE transmissions.
