Printpartsummary
Symptoms:
  • Broken clutch drum
  • No Forward
  • Ratio codes
  • Slipping
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.

Video

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

Smart-Tech® Forward Clutch Drum

Part No.

76654-01K

Smart-Tech® Forward Clutch Drum
  • Smart-Tech® Forward Clutch Drum

  • 76654-01k_details

    OE Forward Clutch Drum vs. Sonnax Smart-Tech Drum

Small_76654-01k Small_76654-01k_details

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

Smart-Tech® Forward Clutch Drum

Part No. 76654-01K

Compatible with ISS-equipped and non ISS-equipped applications

Complaint:

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

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.

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
  • Patent Pending

Related Parts

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Stop 4R70W Drum Failure with the Smart-Tech® Forward Clutch Drum

Sonnax Smart-Tech® products are the best of the best for the ULTIMATE in transmission performance. To tackle chronic forward clutch drum breakage in 4R70W series units, Sonnax designed the stronger, more durable Smart-Tech forward clutch drum 76654-01K. In this video you’ll learn the root causes of 4R70W drum failure and how the Sonnax drum‘s radical improvements protect transmissions from harm.

Contact a Sonnax Distributor to purchase this part.