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