The introduction of the 68RFE six-speed automatic brought better gear spacing and drivability, but it gained a reputation for being the "weak link" in the powertrain. Finally, the AS69RC Aisin transmission emerged as the heavy-duty alternative for high-output models, offering a much sturdier construction designed for commercial-grade towing. Critical Weak Points and Why They Fail
Increased Line Pressure: Using an aftermarket valve body or a transmission control module (TCM) tune can increase internal oil pressure. Higher pressure results in firmer shifts and significantly more clamping force on the clutch packs.
For decades, Dodge and RAM trucks have paired Cummins engines with a variety of automatic and manual transmissions. In the early days, the 47RE and 48RE four-speed automatics were the standard. While simple, they often struggled with heat and internal pressure issues when owners began adding performance tuners. cummin tranny cum updated
Stock Torque Converters: The single-disc factory converters often slip under heavy loads, leading to fluid contamination and eventual burnt clutches.Input Shafts: Under high horsepower or sudden "boosted" launches, the factory input shaft can snap like a toothpick.Valve Body Pressures: Low line pressure in stock units prevents the clutches from holding tightly, leading to premature wear and "flare" shifts. Essential Updates for Performance and Towing
The Cummins engine is designed to last half a million miles. By updating the transmission to match that durability, you ensure that your truck remains a reliable powerhouse for years to come. The introduction of the 68RFE six-speed automatic brought
If you are looking to update your transmission to match the power of your Cummins, there are several "must-have" modifications that experts recommend.
For many owners, the best update is replacing the stock unit entirely with a "built" transmission. Companies specializing in Cummins performance offer "Stage 1" through "Stage 4" builds. These units come pre-assembled with all the updated internals mentioned above, often including proprietary clutch materials and machined drums that can hold double the factory torque ratings. Maintaining Your Updated Setup Higher pressure results in firmer shifts and significantly
Billet Internal Shafts: For those pushing over 500 horsepower, billet steel input, intermediate, and output shafts are essential insurance against catastrophic mechanical failure.