In Aisin Warner 55-50SN and 55-51SN transmissions, bore wear at the Line Pressure Control (LPC) accumulator bore is common. Throttle pressure (SLT) acts on this piston in all gears, which moves the piston against the springs to dampen any pressure irregularities in the SLT circuit. Wear in the bore can allow SLT pressure to exhaust, and creates ridges that cause the piston to jam or bind in the bore. Either results in the inability of SLT dampening, which can create erratic SLT pressure, low pressure, delayed shifts, and various flared and harsh shifts. Sonnax LPC accumulator piston kit S89950K provides positive seals on both ends of the piston to seal worn bores, and prevent the metal-to-metal contact between piston and bore that can result in sticking issues. O-Rings eliminate fluid leakage between LPC piston and bore as well as the metal-to-metal contact between piston and bore that causes wear; Drop-in Zip Valve™ parts install quickly and easily
Accumulator Piston Kit; Line Pressure Control
