A common problem in 700-R4 transmissions is burned bands and/or 3-4 clutches. This failure can be reduced by eliminating throttle boost oil leakage. The Sonnax replacement assemblies 77917-02K, 77917-03K, and 77917-04K eliminate these problems.
TV boost valve and sleeve are manufactured from hardened steel for better wear resistance.
Kits available in three sizes for .423", .471" and .500" diameters.