Description
2004R / 4L60 Reverse Boost Valve Kit, Sonnax K77898.
Vehicles with GM 200-4R and 4L60 transmissions often have problems with poor Reverse boost or upshifts in manual low. The worn Reverse boost valve sleeve or wear at the pump body cause this issue. Sonnax offers a larger ratio (.283″) Reverse boost valve kit K77898 to restore the hydraulic integrity of the assembly.
The differences in thermal expansion rates of steel and aluminum cause the sleeve to scrub the bore excessively as it approaches operating temperature.
- Sleeve O-rings seal the Reverse boost circuit and prevent leakage from the pump body bore
- Hardened steel is used to make sleeves and valves for increased wear resistance.
- To improve sealing and stabilizing capabilities for preventing bore wear and lengthen sleeve lands, we actively adjust them.
- The reverse boost valve spool lands have been extended to help maintain hydraulic integrity.
- Drop-in Zip Valve parts install quickly and easily
- Valve
- Sleeve
- O-Rings (2)
Symptoms:
- Low Reverse boost
- Delayed Reverse
- Low line pressure
- Poor upshift in manual low
Cause:
Worn Reverse boost valve sleeve or wear at pump body.
Correction:
The hardened steel Reverse boost valve kit from Sonnax, with a large ratio and drop-in design, includes O-rings for sealing the Reverse boost circuit and preventing leakage.
