General Motors 180, 180C, & 4L30E Transmissions
Release oil for the rear servo in THM 180 and it's four speed successor, the 4L30E, also happens to be apply oil for the third clutch. Normally, the tight fit of the pin in it's bore seals the oil, allowing the transmission to use the servo's release as an accumulator. The problem is that as the servo applies and releases, the pin wears the case. This wear in the case creates a gap through which third clutch oil leaks, causing a lack of apply pressure to the clutch and release pressure on the servo. With this loss of pressure, the transmission's service life, even after a rebuild, is seriously shortened.
The 4L30E kit contains tooling necessary to repair the rear servo pin bore. It utilizes the same proven brass bushing found in our AOD and AODE kits, and is available as a BLACK series Master or Sub kit.