The GM 4L60E transmission is a workhorse, but even the strongest transmissions need a rebuild eventually. This guide focuses on rebuilding the input drum and upgrading the 3-4 clutch pack, crucial components for a successful Gm 4l60e Rebuild. This process requires careful attention to detail and precise measurements.
The input drum assembly houses the friction plates, steel plates, and the input sun gear. Before assembly, ensure all friction plates are presoaked in transmission fluid for at least 15 minutes to prevent glazing during the initial load test. Some sprag assemblies have a removable sun gear, while others are secured by a dust cover. Install the sun gear if it’s the removable type.
The 3-4 clutch upgrade is a common modification during a GM 4L60E rebuild to improve durability and shift performance. This upgrade typically includes nine friction plates, nine steel plates, a thinner pressure plate, and a thinner snap ring. Achieving proper clearance is crucial for optimal performance.
While the kit provides nine steels, using a combination of the new thinner steels and the original thicker steels might be necessary to achieve the desired clearance. Stack and measure the clutch pack with different combinations of steels and snap rings (both the original and the thinner one included in the kit) to achieve the target clearance. The recommended clearance is between .025″ and .040″. A stack up of .034″ is a good starting point. The 3-4 clutch pack assembly starts with the backing plate (with the legs facing down, clicking onto the 3-4 clutch ring), followed by alternating friction and steel plates, ending with a friction plate. The top apply plate and snap ring are installed last.
Five small booster springs are often a point of contention during a rebuild. Some builders recommend removing them, while others suggest installing them. ATSG recommends removal. Experimentation and careful observation might be required to determine the best approach for your specific application.
After assembling the 3-4 clutch pack, the input drum is completed by installing a washer and then the bearing onto the back of the drum. Ensure the black side of the bearing faces upwards. Use a heavy-duty tack lube to hold these components in place during assembly.
A successful GM 4L60E rebuild hinges on accurate measurements and careful assembly, particularly with the input drum and 3-4 clutch pack. This guide provides a foundational understanding of the process. Always consult a comprehensive GM 4L60E rebuild manual for detailed instructions and torque specifications.
