Symptoms:

  • No Forward
  • Slipping gears
  • Broken clutch drum
  • Ratio codes

Cause:

OE forward clutch drum splits at snap ring groove due to manufacturing process, creating no or slipping forward clutch apply.

Correction:

Restore proper gear engagement and hold by installing sturdier, forged Sonnax forward clutch drum.

4R70E, 4R70W, 4R75E, 4R75W, AODE

Smart-Tech® Forward Clutch Drum
Part No. 76654-01K

Compatible with ISS-equipped and non ISS-equipped applications

View Instructions Find a Distributor

A common failure of listed Ford transmissions is cracking of the forward drum at the snap ring groove. The manufacturing process of the OE snap ring groove creates high-stress points around the circumference of the drum. The drum is active in 1st, 2nd and 3rd gear ranges and suffers the most abuse on a forced 4-3 kick down when it reapplies at higher pressure.

The concurrent pressure from the forward clutch piston combined with the high stress at the snap ring groove causes the upper portion of the drum to split and separate at the groove. Depending on severity of crack, this can result in no forward engagement or slipping in 1st, 2nd and 3rd gear. The forged, one-piece construction of the Sonnax Smart-Tech forward clutch drum 76654-01K eliminates weakness at these stress points.

  • Increased groove depth for additional ring support
  • One-piece forged material provides increased strength and durability over the OE stamped drum

I have used this in a 600whp supercharged Mercury Marauder along with other Sonnax parts, and man did the customer love what we did. You guys are the masterminds of this industry.

J. Johnson
Crystal Lake Transmissions

  • 76654 01k
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