• Low line rise
  • Early upshifts
  • Soft upshifts
  • Premature 3-4 clutch failure
  • Low line pressure


The steel TV plunger wears the TV plunger sleeve, allowing TV feed oil to leak past the plunger and exhaust.


Sonnax drop-in throttle valve plunger kit restores the hydraulic integrity of the circuit.


Throttle Valve Plunger Kit
Part No. 77966-94MK

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Poor line rise or no detent downshifts can be common complaints in vehicles with a GM 4L60 (THM700-R4) transmission. The steel throttle valve plunger continuously reciprocates within the aluminum throttle valve plunger sleeve, wearing the sleeve. This wear allows throttle valve feed oil to leak past the plunger and exhaust, resulting in poor line rise and problematic downshifts. In addition, the OE spring is weak and can result in low line rise, insufficient throttle pressure and, ultimately, 3-4 clutch failure. Sonnax throttle valve plunger valve kit 77966-94MK includes an improved throttle valve spring designed to maintain higher line pressure and improved TV performance.

  • Sleeve is made from high-quality aluminum to prevent wear
  • Sleeve and plunger have been tightly toleranced to restore hydraulic integrity
  • Kit eliminates the part throttle sleeve orifice
  • Drop-in Zip Valve™ parts install quickly and easily
Learn More About Zip Valve™ Drop-In Repairs

Prevents forced 4-3 kickdown below three-quarter throttle.

  • Sleeve
  • Plunger
  • Spring

Sonnax valve body layouts provide a detailed overview of individual units making it quick and easy to determine what’s available for the specific valve body you’re working on. See all Sonnax valve body layouts.

GM 4L60 (700-R4) Valve Body Layout

GM 4L60 (700-R4) Valve Body Layout
  • 4L60 Throttle Valve Plunger Kit 77966-94MK
  • 4L60 Throttle Valve Plunger Kit 77966-94MK