Servo cover wears and direct clutch/servo release oil is lost, eventually resulting in direct clutch failure.
This servo piston cover with o-ring is designed to overcome piston wear and ensure hydraulic seal of direct clutch oil.
In vehicles with A727 (71-later), and 46 & 47RH/RE transmissions it is common to have long slide 2-3 shifts, direct (front) clutch failure or poor line pressure. These complaints can be caused by the front servo piston cover bore wearing the pin bore. In 3rd gear, direct clutch oil is present under the servo cover to release the band. Oil leaks due to a worn cover affect 2-3 shift and direct clutch durability. Sonnax has designed an upgraded front servo piston cover 22827-01 with an O-ring in the pin bore diameter.
O-ring provides positive hydraulic seal between the servo cover and apply rod and prevents direct (front) clutch oil leaks.