Sonnax reinforced OE input housing and heavy-duty input shaft kit 77733-13K is a great upgrade for 4L60-E, 4L65-E and 4L70-E high performance and heavy-duty applications. Shaft is made of specially heat-treated steel with very hard outer layers and a more ductile inner core for strength and resistance to fracture. Feed holes are chamfered to reduce stress and the shaft is further processed by shot peening and deep cryogenic treatment.
The high-strength 300mm non-reluctor style input shaft and OE housing comes with a reinforcement sleeve installed on the housing to strengthen the aluminum splines, which are otherwise prone to cracking. This kit includes a custom-manufactured overrun piston that is designed to be used only with a stamped steel forward piston, eliminating the need to use OE cast forward piston or aftermarket billet forward piston.