• Smart-Tech Input Housing with 300mm Reluctor-Style Input Shaft Assembly
• PTFE Impregnated Rear Stator Support Bushing
• Input Drum Reinforcement Sleeve installed
• Overrun Piston Inner Seal
• Overrun Piston Outer Seal
• Overrun Piston
• 3-4 Clutch Apply Plate
• 3-4 Clutch Return Springs (10)
• Bolt-on Anchor Plate
• Socket Head Cap Screws (15)
• Fits 300mm reluctor-style units only.

Designed to fit 300mm reluctor-style units, the Sonnax Smart-Tech input housing kit with heavy duty input shaft 77733-12K addresses six weak areas of the GM 4L60-E, 4L65-E, 4L70-E input housing: (1) flexing/bowing of the 3-4 backing plate, (2) limited 3-4 clutch torque capacity, (3) 3-4 snap-ring blow-out, (4) input housing breakage near the input shaft spline, (5) input housing fatigue failure and (6) input shaft failure.

Flexing/bowing of OE and other aftermarket backing plates is eliminated with Sonnax's heavy duty bolt-on anchoring plate. This unique design ensures even clamping of the 3-4 clutches in higher horsepower, higher pressure applications. By eliminating the 3-4 snap ring and using a thinner yet stiffer apply plate, space is made available for additional frictions and steels. This makes it possible to simultaneously increase clutch torque capacity and eliminate the possibility of retaining ring blow-out. A steel reinforcement sleeve prevents breakage in the spline area. Housing fatigue failure resistance and housing life are significantly improved with a special treatment process that greatly reduces stress crack formation.

For strength and resistance to fracture, the Sonnax input shaft for 300mm reluctor-style units is made of high strength steel that is specially heat treated with a very hard outer layer with a more ductile inner core. The feed holes are chamfered to reduce stress and the shaft is further processed by shot peening and deep cryogenic treatment.