Installing a transmission means safely supporting the vehicle, removing the driveshaft or axles, disconnecting the cooler lines, wiring, shift linkage and mounts, supporting the engine, unbolting the bell housing and lowering the old unit, then reversing the process with the replacement. Correctly seating the torque converter, flushing the cooler and filling with the right fluid are the steps that most often decide whether a replacement transmission lasts. It is a heavy, involved job that needs a transmission jack and service information for your vehicle.
Overview of the steps
- Disconnect the battery, raise and support the vehicle securely, and drain the fluid.
- Remove the driveshaft or axles, exhaust parts in the way, and the starter if required.
- Disconnect cooler lines, wiring connectors, shift linkage and the dipstick tube.
- Mark and remove the torque converter bolts or nuts through the inspection opening.
- Support the engine, remove the crossmember and mount, and unbolt the bell housing.
- Lower the transmission on a transmission jack, keeping the converter from falling out.
- Install the replacement in reverse order, then fill and check fluid.
The steps that matter most
- Seat the torque converter fully into the pump before mounting the transmission; a converter that is not engaged can destroy the pump when the bolts are tightened.
- Flush or replace the cooler and lines. Debris from the old transmission will otherwise flow straight into the new one; see transmission cooler.
- Use the correct fluid and fill procedure; see how much transmission fluid do I need? and transmission fluid chart.
- Relearn or program the transmission controller if the vehicle requires it.
Before you order
Match the replacement by transmission code, model year, engine, two- or four-wheel drive and, for trucks, the tailshaft and transfer case style. Electronic transmissions also need the right controller setup. Compare the old and new units side by side before installation; see how to check transmission fluid for the post-install check.
Can you install a transmission by yourself?
Experienced home mechanics do, but it needs a transmission jack, solid jack stands, the right tools and a helper is strongly recommended. The transmission is heavy and awkward; never work under a vehicle supported only by a jack.
How long it takes
See how long to replace a transmission. Four-wheel-drive and front-wheel-drive vehicles usually take longer than two-wheel-drive trucks.
After installation
Check for leaks, recheck the fluid level hot, and drive gently while the adaptive values learn. Match the replacement exactly to your vehicle; see what transmission do I have? and our transmissions.
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