Overall, the 4L80E is a fairly heavy-duty transmission.

One of its lesser points is the cast aluminum reverse servo piston. This weak link is prone to breakage while enduring the repetitive cycling that occurs in plow truck applications, when the boost valve has worn or when the pressure spikes.

Our solution is this burly billet aluminum version. A direct replacement, it’s much stronger than the OEM casting by nature. Our engineers have made an effective leap forward in design to ensure your customers’ demanded durability.

The factory unit is weak where it needs to be strong: the area around the apply pin. We’ve engineered ours far thicker than the original to combat the stresses of any side loading. Another touch is the additional thickness above the sealing ring groove that helps to stabilize the piston in the bore.

Our support bolts into place from two directions to hold firm: Through the servo apply pin hole and the hole originally retaining the band anchor plug.