Severe transmission damage can occur if you try to tow a car with an automatic transmission incorrectly. The transmission is affected even if the car is in neutral. The key is to tow the vehicle without having the internal workings of the transmission being involved.
Determine if you will be towing a rear wheel, front wheel, or all wheel drive vehicle with an automatic transmission. Each type of vehicle requires a different approach to towing. Consult your owner's manual for the car if you are uncertain about this.
Tow a rear wheel drive vehicle with a tow bar and hitch. Drop the driveshaft by removing the universal joint at the differential or rear end. You do this by removing the two bolts that hold two of the four arms of the universal joint in place. Lower this end of the driveshaft gently to the ground and replace the bolts and yoke back into place so that they will not get lost. You can store them if you choose. Tug lightly on the driveshaft and the front portion with the front universal joint should pull from the transmission. Try not to let it slam to the ground. Store the driveshaft in a vehicle to take it along for use later.
Place the tow bar in front of the car. Make sure that all safety devices are attached and functioning. Raise the tongue of the tow bar and lower it on to the ball on the hitch attached to the tow vehicle. Tighten the tow bar securely to the ball and attach any safety chains from the tow bar to the tow vehicle.
Use a car dolly for front wheel and all wheel drive vehicles. Attach the car dolly to the tow vehicle just like a tow bar. It sits on the hitch and gets tightened to the ball. Fasten all safety chains. Also, connect the light plug to a socket on the tow vehicle to activate the brake lights and indicators. If there is no socket, you will have to purchase a kit from a parts store to provide power to the trailer lights. Install it on your vehicle according to the manufacturer's instructions.
Drive the car on to the car dolly. Only the front wheels will rest on the dolly; the rear tires will roll freely on the car. Use the chains to secure the car to the dolly. You must remove the driveshaft from the all wheel drive vehicle. This is done the same way as a rear wheel drive car. The car should be ready to tow with no transmission damage.
Use a lighting kit from a parts store or the rental agency to wire tail and brake lights onto the vehicle being towed. Make sure all of the lights function correctly before beginning to tow the car. You also have the option of using a car trailer instead of a tow bar or car dolly to tow any type of car without worrying about the transmission.
Tow the car about 1/4 to 1/2 mile and stop to inspect all of the hookups. Make certain that all lights are still working. Check safety chains and the hitch for a secure fit. If all is well, continue with the towing. For long trips, check everything each time that you stop for any reason.
Always try to have at least one person to help you prepare a car for towing. Drive slightly below the speed limit until you are comfortable towing the other vehicle.
Make sure the tow vehicle and hitch are rated to handle the weight of the car or trailer being towed.