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  • Low cooler flow
  • No lockup
  • Code 1741
  • Engine stall on FWD engagement
  • Poor converter fill & delayed engagements


The modulator valve bore wears at either end or can stick in either position. Fluid control at the inboard circuit prevents lockup valve travel in reverse. The outer circuits affect converter flow and TCC apply through the solenoid.


The Sonnax sleeve reduces cross leakage and improves TCC solenoid control over the valve and apply oil.

4R44E, 4R55E, 5R44E, 5R55E

TCC Modulator Sleeve Kit
Part No. 37947-07K

View Instructions

Constant oscillation of the torque converter clutch (TCC) modulator valve creates wear in the valve body bore, which can allow converter solenoid oil to exhaust. This prevents the TCC modulator valve from stroking fully to the apply position, which can create a no lockup complaint and/or set a 1741 code. Wear at the other end of the valve can prevent TCC release, resulting in cover dragging and stall on forward engagement. Sonnax offers a highly wear-resistant aluminum sleeve, 37947-07K, that mates with the OE anodized aluminum valve. Use of this sleeve allows the valve bore to be oversized, and the hydraulic integrity of the bore to be restored.

  • Specially toleranced alloy aluminum sleeve is significantly more wear-resistant than the cast aluminum valve body.
  • Alloy aluminum sleeve provides more contact surface with the valve for increased stability and durability.
  • Kit includes a replacement solenoid regulator valve spring, which is often damaged during valvebody disassembly.
  • The tool kit also works with the 37947-05K pressure regulator valve sleeve kit.
  • Sleeve
  • Spacer
  • Solenoid Regulator Valve Spring

Sonnax valve body layouts provide a detailed overview of individual units making it quick and easy to determine what’s available for the specific valve body you’re working on. See all Sonnax valve body layouts.

Ford 4R/5R44E, 4R/5R55E Valve Body Layout

Ford 4r 5r44e thumb

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  • 37947 07k combo
  • 37947 07k