Product Description
200-4R, 4L60 Reverse Boost Valve Kit
Part No. K77898A
Large Ratio, Factory Style, No O-Rings
You need this if... 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 increased wear resistance
Sleeve lands have been lengthened to add better sealing and stabilizing capabilities to prevent bore wear
The reverse boost valve spool lands have been lengthened to aid in maintaining hydraulic integrity
Drop-in Zip Valve™ parts install quickly and easily
Learn More About Zip Valve™ Drop-In Repairs
Contents-
Valve
Sleeve
