105 East Poplar Avenue - Cameron, WI
715-458-2617

4L80

General Motors 375, 400, 425, & 4L80E Transmissions

Black Series

4l80 kits

Release oil for the rear servo in THM 400 and it's four speed successor, the 4L80E, also happens to be apply oil for the second 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 the intermediate 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 4L80 kit contains tooling necessary to repair the rear servo pin bore, and is available as a Master or Sub kit.

Instructions

FLYER

SF-99 Servo Pin Bore Repair System

The SF-99 servo pin bore repair system is a set of tools that allow you to easily repair worn servo pin bores with no special machinery, all that is needed is a drill and a hammer.

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Choose Tool By Kit Name

We offer different tooling for several transmissions. Choose tool by kit name below.

Choose Tool By Transmission Model

We offer different tooling for several transmissions. Choose tool by transmission model below.