A common problem in GM 200-4R and 4L60 transmissions is burned bands and/or 3-4 clutches. This failure can be reduced by eliminating throttle boost oil leakage. The Sonnax TV boost valve kits [77917-01K] (.423" dia.), 77917-471 (.471" dia.) and 77917-500 (500" dia.) eliminate these problems for a variety of applications. For higher line pressure for towing and off-road, use Sonnax TV boost valve kit 77917-471.

Throttle valve boost valve and sleeve are made from made from hardened steel for better wear resistance
O-Rings on sleeve separate throttle pressure and Reverse boost circuits, providing additional protection against cross-leaks
O-Rings prevent loss of oil between the outside diameter of the throttle valve sleeve and pump body
Drop-in Zip Valve™ parts install quickly and easily


Sonnax Part No.
Sleeve Dia.
Performance Application


[77917-01K]
.423" dia.
Minimum line pressure for V8 applications

77917-471
.471" dia.
Higher line pressure for towing and off-road

77917-500
.500" dia
Maximum line pressure & shift feel for high performance applications


Learn More About Zip Valve™ Drop-In Repairs

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