4R70E, 4R70W, 4R75E, 4R75W, AOD, AODE Transmission

Smart-Tech® High Capacity Forward Clutch Drum Kit

Part No. 76655-01K

Forward clutch durability is a known issue in Ford performance applications. While some solutions eliminate the wave plate to fit more clutches, this often leads to harsh engagements and poor shift timing. Additionally, stamped drums frequently crack at the snap ring groove.

The Sonnax Smart-Tech® high capacity forward clutch drum kit 76655-01K solves these problems by:

• Increasing clutch capacity by 20% using six OE-thickness frictions and steels
• Retaining the wave plate for smooth engagement
• Featuring a one-piece forged drum that eliminates stress points and prevents cracking

Why It Matters

The OE snap ring groove creates high-stress points that can cause the drum to split under pressure—especially during forced 4–3 kickdowns. This can result in slipping or loss of forward engagement in 1st, 2nd, and 3rd gears. The forged Sonnax drum is more durable and includes deeper grooves for better ring support.

Kit Contents

• High Capacity Drum
• Bottom Steel Plate – 0.055" Thick

Installation Note

If replacing an AOD cast forward drum, update related components to AODE versions. This includes the forward clutch pack (frictions, steels, waved plates, backing plate, retaining ring). You must also either:

• Machine tips of reluctor from forward drum
• Or update sun gear shell and reverse drum with AODE versions

Warning: See caution regarding riveted sun gear shell.