The AX4S, AX4N (4F50N) single clutch converters have a piston that is prone to cracking due to manufacturing flaws. A cracked piston will not only lock up improperly, but will shave material off the OE friction ring. This loose friction material will contaminate the whole transmission. The Sonnax FD-DA-19PB, a fully machined forging, is a replacement piston plate that corrects this OE problem. Friction ringB66300HTLis recommended for use with
FD-DA-19PB.

• Replaces the OE piston that is prone to cracking
• Machined from a steel forging
• Increased wall thickness for greater stiffness
• Lock-up surface machined to specific requirements to ensure a great bond