How to Overhaul Transmission

Overhauling a transmission requires completely removing it from the vehicle, draining the fluid and disassembling all the internal parts. Each part is inspected and cleaned. If a part is worn or damaged, the part needs to be replaced. Overhaul kits contain standard replacement parts needed in every transmission overhaul such as gaskets, bands and clutches.

Things You'll Need

  • Garage
  • Wrenches
  • Rebuild kit
  • Manual

Automatic Transmission Overhaul

  • Disassemble the transmission and inspect all internal parts. Clean the parts and replace any that are worn or damaged with new original parts. The governor and then the oil pan is a good place to start. If there is damage inside the transmission, there will likely be debris in the oil pan.

  • Reassemble the transmission with the newly cleaned or replaced parts. Be sure to replace all seals, gaskets, bands and clutches with the new ones from the build kit. Use lubricant on any moving parts before placing them back in the transmission.

  • Consult your manual for proper torque requirements and test all pistons and valves with compressed air to be sure they are working properly.

Manual Transmission Overhaul

  • Disassemble the transmission, first removing the transfer case. Inspect all internal parts for damage and replace them with new OEM parts. Carefully clean all other parts and place them on your workbench.

  • Disassemble the clutch housing and replace the clutch with the new parts in your build kit.

  • Disassemble the reverse idle gear. Be sure to use gear oil on the newly cleaned or replaced gears to ensure smooth movement. Also check to be sure that the gear and shaft turn quietly and smoothly when reassembled.

  • Reassemble the transmission parts in the same order as they were disassembled. Consult your manual for torque requirements.