Sonnax K77898 Transmission Reverse Boost Valve Kit (Large Ratio, O-Ring Style)
Specifications
| Return Shipping Will Be Paid By | Seller |
| Returns Accepted | Returns Accepted |
| Item Must Be Returned Within | 30 Days |
| Brand | Sonnax |
| Other Part Number | S74507RDK |
| Type | Pump Component |
| Manufacturer Part Number | K77898 |
| Material | Steel |
| Universal Fitment | Yes |
| Performance Part | Yes |
200-4R, 4L60, 700R4 Reverse Boost Valve Kit Part No. K77898 Large Ratio, O-Ring Style Vehicles with GM 200-4R and 4L60 transmissions often have problems with poor Reverse boost or upshifts in manual low. These are generally caused by a worn Reverse boost valve sleeve or wear at the pump body. Sonnax offers a larger ratio (.283") Reverse boost valve kit K77898 to restore the hydraulic integrity of the assembly. 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 O-rings seal the Reverse boost circuit and prevent leakage from the pump body 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 Reverse boost valve spool lands have been lengthened to aid in maintaining hydraulic integrity Contents Valve Sleeve O-Rings (2)