• Code 628, 1741
  • TCC apply concerns
  • TCC cycling
  • TCC surge
  • High TCC slip RPM
  • Overheated fluid
  • Overheated converter


Converter apply pressure is reduced as the bore wears and the OE end plugs become loose.


Sonnax TCC regulator sleeve kit eliminates the inner plug by incorporating it into the sleeve, which then repairs the TCC regulator valve bore. The large end plug that retains the assembly is sealed and has increased surface contact to avoid movement.

4R44E, 4R55E, 5R44E, 5R55E

TCC Regulator Sleeve Kit
Part No. 37947-09K

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Constant oscillation of the converter clutch regulator valve creates wear in the valve body bore. Also, the small plug separating this regulator valve and the inboard coast clutch valve oscillates due to opposing spring and oil forces, creating bore wear and a path for oil pressure to exhaust. Excessive wear at these areas prevents regulated line pressure from supplying the converter clutch with apply and release pressures, causing converter complaints and setting 628 and 1741 codes.

Sonnax TCC regulator sleeve kit 37947-09K mates with the OE anodized aluminum valve or our 37947-38 replacement valve. Use of this sleeve allows the valve bore to be oversized, and the hydraulic integrity of the bore to be restored. The sleeve design also incorporates the middle end plug, preventing future bore wear at this location. An O-ringed outboard end plug is also supplied to maintain proper balance line pressure and ensure the proper stroking of the regulator valve.

  • 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
  • Alloy aluminum sleeve incorporates the troublesome middle end plug to prevent wear that results in no 4th Gear
  • O-ringed outboard end plug has more contact area and a positive seal for better maintenance of balance line pressure
  • Kit includes a replacement solenoid regulator valve spring and coast clutch valve spring, which are often damaged during valve body disassembly
  • The kit includes lube modification plugs for repeated 1741 codes and TCC slippage concerns
  • Sleeve can be used with OE original or Sonnax replacement valve 37947-38
  • Sleeve
  • End Plug
  • Coast Clutch Valve Spring
  • Solenoid Regulator Valve Spring
  • Spring Pins (2)
  • L Shaped Retaining Pin
  • O-Rings (2) 1 Extra
  • Lube Modification Plugs (3) 1 Extra, Not Shown
  • Rivets (3) 1 Extra, Not Shown

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 4R44E, 5R44E, 4R55E, 5R55E Valve Body Layout

Ford 4R44E, 5R44E, 4R55E, 5R55E Valve Body Layout
  • 4R44E, 4R55E, 5R44E, 5R55E TCC Regulator Sleeve Kit 37947-09K
  • 4R44E, 4R55E, 5R44E, 5R55E TCC Regulator Sleeve Kit 37947-09K