Imagine racing a Ford with an automatic that can go head-to-head with the durability of a Powerglide, 400 or 4L80. Confidently running big power through AODE, 4R70W series transmissions is now a reality. Sonnax — the most trusted name in transmission innovation — is proud to announce the innovative new Smart-Tech® direct clutch drum and shaft kit. Proven to handle even the most extreme torque and horsepower, it is the first and only upgrade to eliminate the direct clutch as the Achilles heel of this transmission family.
While AODE, 4R70W units can handle big power, the whole direct clutch area is major obstacle because its design long ago fell behind advances in engine output. Smoked clutches are chronic due to insufficient torque capacity, and the fragile stub shaft is prone to shearing at the worst times. Aside from knowing that extra torque can quickly kill their transmission, many drivers never realized the exact nature of this ticking time bomb until they lose 3rd and 4th gears. Worse, they then learned there was no way to guarantee it wouldn’t happen again. Builders struggled for years chasing direct drum failures because the right components just weren’t available to solve all of its design flaws.
Sonnax dug into the root cause of both shaft and clutch problems to develop the patented Smart-Tech kit. The foundation is a revolutionary one-piece drum and shaft design that eliminates the weak connection point where drum splines strip and shafts break. Even other aftermarket upgrades that rely on a heavy-duty stub shaft will sheer in this area under extreme conditions. The Smart-Tech shaft itself is significantly thicker — two times stronger than the OE — and works with a unique, heavy-duty sun gear that installs over the top. To optimize protection against clutch burn-up, the custom drum and piston hold one extra friction for 17% more clutch capacity.
This Smart-Tech kit is an ideal, all-in-one upgrade for any vehicle pushing the limits of stock components. It installs easily into all Ford AODE, 4R70E/W and 4R75E/W transmissions with 2.84/1.55 gear sets. A late AODE sun gear can be used in place of the Sonnax gear with 2.40/1.46 gear sets. For details on this product (Sonnax Part No. 76656-01K) and related upgrades, visit www.sonnax.com/ford_direct_drum. Sonnax transmission components are available from performance parts distributors and are the trusted choice of top performance specialists worldwide.
This story was originally published on April 9, 2019. 
