A while back, I entered my Chevy in a “Classy and Classic” car show in Niwot, Co. as a “car in progress.” We had to tow the car to get it to the show, and the Chevy is an automatic.

I checked with 5 different people about the proper way to tow an automatic, and gained as many different opinions on the subject. Some people thought that towing an automatic a few miles would be fine, while others were convinced that this action would destroy the car's transmission.

In the end, I opted not to take any risks. The transmission was working when I parked the car, and I wanted to keep it that way.

Everyone agreed that the safest way to tow a car with an automatic transmission is to disconnect the drive line, through the U-joints. The Chevy has a single U-joint, located somewhat inside of the rear of the transmission. (There is no U-joint near the differential). The drive line is encased inside of a metal tube and disconnects on the transmission side only. The metal tube forms a ball joint, which fits into the end of the transmission. By working together, the U-joint and the ball-joint permit small relative motions—in 6 degrees of freedom—between the transmission and the rear axel.

Once disconnected, the encased drive line can be tilted slightly to remove the U-joint. As it is lowered on the transmission side, the entire differential and rear axel rotate accordingly.

A drawing of the U-joints and the transmission are shown on the next page.