When rebuilding high performance or heavy-duty Ford C6 transmissions, it is common to find a worn boost sleeve in the clicker type valve body. This wear causes poor line rise, which results in erratic shift timing, reverse shudder or direct clutch failure. This can be caused by the reciprocating boost valve wearing the inside diameter of the boost sleeve. When this occurs, oil that enters the modulated line pressure orifice leaks past the boost valve and exhausts through the reverse orifice, resulting in poor or no line rise. The outside diameter of the boost sleeve may allow some leakage through the valve body, which can result in insufficient line rise. Sonnax boost valve kit 36941-01K to eliminates the above problems. Replace the boost valve and sleeve to restore performance and to reduce the chance of premature failure.
A number of boost valve kits are available for this unit:
Contact a Sonnax Parts Distributor.
To check for a worn boost sleeve, perform the Wet Air Test. With the boost valve assembly still in the valve body, place a small amount of oil into the modulated line pressure orifice. Follow this with low air pressure. There should be little to no air or oil leakage out of the reverse or exhaust circuits.