Cadillac STS rear end banging sound during transmission shifts on Cadillac STS

Some Cadillac STS owners report experiencing a banging sound in the rear end during transmission shifts, which may indicate several potential issues. These owners have noted that the clunking noise can be attributed to a bad differential, particularly when hitting small bumps or dips at low speeds. Additionally, worn-out shock absorbers, loose suspension bushings, or problems with the exhaust system are common causes of rear end noises. Some have found that changing the rear end fluid and adding a positraction additive can help resolve the issue, especially if the positraction plates are sticking. Furthermore, loose components under the rear seat cushion or in the right rear fender may also contribute to the clunking sound. It is recommended that owners check the shock absorbers in the rear suspension knuckle for any contact issues and consult a professional mechanic for a thorough inspection and diagnosis of the problem.