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Sonnax K77898 Transmission Reverse Boost Valve Kit (Large Ratio, O-Ring Style)

Sonnax K77898 Transmission Reverse Boost Valve Kit (Large Ratio, O-Ring Style)

by Sonnax
SKU S74507RDK
$22.47 - $22.47
$22.47
$22.47 - $22.47
$22.47
Availability:
in stock, ready to be shipped

Delivery time

You will receive your package in 2–5 business days within the contiguous U.S.

Brand: Sonnax

Other Part Number: S74507RDK

Type: Pump Component

Items Included: Reverse Boost Valve and Sleeve with O-Rings

Manufacturer Part Number: K77898

Material: Steel

Universal Fitment: Yes

Vintage Part: No

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
  • Valve
  • Sleeve
  • O-Rings (2)

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