Sonnax K77898A Reverse Boost Valve Kit 200-4R, 4L60

Brand: SonnaxOther Part Number: S74507RBKType: Pump Boost valve kitInterchange Part Number: S74507RCKItems Included: Reverse Boost Valve and Sleeve KitManufacturer Part Number: K77898AMaterial: SteelUniversal Fitment: YesVintage Part: NoPerformance Part: Yes 200-4R, 4L60, 700R4 Transmission Reverse Boost Valve KitPart No. K77898A Large Ratio, Factory-Style Sleeve, No O-Rings Vehicles with GM 200-4R and 4L60 transmissions often have complaints of poor Reverse boost or upshifts in manual low. This complaint is generally caused by a worn Reverse boost valve sleeve or wear at the pump body. To resolve these problems, Sonnax offers larger ratio (.283"), factory-style Reverse boost valve kit K77898A. Due to the differences in the thermal expansion rate of steel and aluminum when the transmission approaches operating temperature, the sleeve has been allowed excessive clearance and scrubs the bore. Sleeve and valve are made from hardened steel for inc