A low throttle boost condition is a common complaint in vehicles with a vehicles with GM 4L60 transmissions. This loss of throttle boost oil creates poor line rise and accelerates 3-4 clutch and band failure. In late-model transmissions, the hardened steel throttle valve continuously oscillates in the cast iron valve body bore and eventually wears the three bore diameters. This wear allows throttle valve feed oil to leak past the valve spool and exhaust, resulting in a low throttle boost condition. This excessive leakage can be eliminated by reconditioning the bore and installing Sonnax oversized throttle valve 77968.

• The three spool diameters on this valve are slightly larger than the late-model OE valve, allowing the valve body bore to be modified to restore the hydraulic integrity of the assembly
• Reamer eliminates miscalibration or similar wear when exchanging with another used valve body