In Aisin AW 55-50SN and 55-51SN units, wear at the balance end can cause harsh shifts, high line pressure, converter apply/release problems and lube-related issues. Wear at the other locations can result in soft shifts, low line pressure, and converter problems. Boost sleeve wear reduces the ability of line pressure to rise according to TCM command, resulting in slow line rise and late shifts. Late shifts can often create gear ratio codes. A worn boost sleeve in this unit can also cause a delay in reverse or slippage, eventually burning the low reverse (B3), 1-2 reverse (B5) band and or the direct clutch (C2). Sonnax oversized pressure regulator and boost valve kit 59947-12K restores hydraulic integrity.

• Hardcoat anodized aluminum valves combat premature wear
• The pressure regulator valve has longer length spools for increased valve support.