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