# 74788K

O Ringed End Plug Kit


Also fits AF23/33 and RE5F22A units.


  • Delayed Forward
  • Poor shift quality
  • TCC slip
  • 3-2 Neutral
  • 2-3 Flare
  • Low SLT pressure
  • Overheated fluid

Valves and springs push on the end plugs, eventually causing distortion and excessive clearance between the plug and bore.

Sonnax O-ringed end plugs restore correct circuit pressures.

The primary design function of the OE end plug is to prevent critical pressure loss by capping the bore. OE end plugs rely entirely on small clearances between the end plug and bore to confine hydraulic fluid under fluctuating pressure. End plugs are often tasked with a secondary role functioning as a spring stop or valve stop. The repetitious and varying actions of fluid pressure, spring motion and valve impact cause wear at the end plug and bore mating surface, and can distort the shape of the end plug. This allows critical oil pressure to escape and prevent proper valve function. In the 55-50SN, 55-51SN locations, this results in loss of SLT (throttle) pressure, and drive/line pressure at various bores. The results are the various driveability complaints noted, as well as related burnt clutches and bands.

The end plugs in the Sonnax O-ringed end plug kit have small clearances to mechanically block the bore and include an O-ring seal to provide a positive seal with worn bores to prevent future leakage.

  • No special tools required
  • Prevents loss of critical pressure
  • Sonnax kit services five different bores. Can be used in other bore locations as applicable

O-Ringed End Plugs for AW55-50SN
End Plugs
Forward Clutch Control Front Control VB 9mm
2nd Coast Clutch Control Front Control VB 9mm
Neutral Relay Front Control VB 9mm
M1 Shift Middle Control VB 9mm
3rd Gear Band Release Middle Control VB 11mm


  • End Plugs (4) Small, 9mm
  • End Plug Large, 11mm
  • O-Rings (6) Small, 2 Extra
  • O-Rings (2) Large, 1 Extra

SONNAX Installation Instructions

Type of Product: Sundry Parts
Qty Needed:
Alternative #: