700R4 TRANSMISSION FULL REBUILD PART 1

Introduction

This tutorial provides a comprehensive step-by-step guide for a full rebuild of the 700R4 automatic transmission, based on the first part of a video series by Automatic Transmission. Whether you're a seasoned mechanic or a DIY enthusiast, this guide will walk you through the essential steps involved in disassembling and inspecting the 700R4 transmission, preparing you for the rebuild process.

Step 1: Remove External Components

• Start by removing all external components from the transmission.
• Carefully detach the filler tube. If it's difficult, consider removing it before disassembly.
• Identify and disconnect the throttle valve (TV) cable, governor output speed sensor, and manual linkage.

Step 2: Remove the Governor Cover

• Use a screwdriver to gently tap the governor cover until it pops off.
• Inspect the governor valve to ensure it moves freely. If it’s stuck, tap it gently to loosen it.
• Clean the area and prepare to replace the governor gear if necessary.

Step 3: Remove the Speed Sensor

• Use a 15mm socket to remove the speed sensor. If it's stuck, apply gentle pressure and twist with pliers to extract it.

Step 4: Remove the Extension Housing

• Use a 15mm socket to detach the extension housing from the transmission.
• Inspect the extension housing seal for any cracks or leaks; replace if necessary.

Step 5: Drain Transmission Fluid

• Position a five-gallon bucket under the transmission to catch fluid as you disassemble.
• Allow the fluid to drain completely to prevent spills.

Step 6: Remove Pump Bolts

• Use a 13mm socket to remove the pump bolts.
• Note that these bolts have O-rings; ensure you replace them during reassembly.

Step 7: Inspect the Valve Body

• Detach the valve body and check for wear or damage.
• Pay attention to the check balls; some can be eliminated during the rebuild for improved performance.

Step 8: Disassemble the Pump

• Remove the pump by unscrewing it and inspect the internal components, including the pump rotor and veining for wear.
• Check the pump slide and replace if it shows signs of wear.

Step 9: Detach the Drums and Clutches

• Carefully remove the drum assemblies. Inspect the clutches for signs of wear or water damage.
• Check for any warping or damage in the drums themselves.

Step 10: Inspect the Planetary Gear Assembly

• Remove the planetary gears and inspect for wear.
• Ensure that the outer race and sprag are in good condition; replace if necessary.

Step 11: Clean and Prepare for Rebuild

• Clean all components thoroughly to remove debris and old fluid.
• Inspect all seals and gaskets; replace as needed.

Conclusion

You've now disassembled the 700R4 transmission and inspected its components for wear and damage. This foundational step sets you up for a successful rebuild. In the next part of the series, you will learn about the reassembly process, including how to install new parts and ensure everything functions correctly. Be sure to gather the necessary replacement parts and tools before proceeding to the next steps. Happy rebuilding!