MTV boost loss and insufficient line rise.
These replacement assemblies prevent oil loss between the outside diameter of the TV sleeve and the pump body.
A common problem in 4L60 transmissions is burned bands and/or 3-4 clutches. This failure can be reduced by eliminating throttle boost oil leakage. The Sonnax replacement assemblies 77917-01K (.423" diameter), 77917-471 (.471" diameter) and 77917-500 (500" diameter) eliminate these problems for a variety of applications.
Contact a Sonnax Parts Distributor.