Thumping sound in the rear of Subaru Legacy

I hear a thumping soud in the rear of my '97 Legacy wagon (Brighton model). The sound occurs when the car moves. Once the car has been running for several minutes the sound goes away. Any idea of cause and fix?

Does the noise correspond to any certain condition (weather, time of day etc), or does it happen every time you start to drive the car?

Does the noise seem related to the rotational speed of the wheels? Does using the brakes have any effect on the sound?

This happened to me the other day and I was very worried, what with the awd system and all…but I stopped on the side of the road and looked for anything obvious it could be, checked for play on the brakes…it went away within one or two miles though, I decided to check my tire pressures…lo and behold, my rear tires were not the same psi, my passenger side needed about 12psi to get back to matching.

I decided that in my case it was mostly likely the change in air pressure (atmospheric) that accompanies the weather had led to low tire pressure and a “flat spot” in the tires because once warmer it went away, once I filled the tires back to specs, it stayed away…I only use this car about once a week, but went ahead and drove it today to be sure it felt good…all is well.

Rotate your tires front to back. see if that changes anything. and check the tire pressure.

P.S. Let your spouse out of the trunk. They will generally stop all that racket back there once they are free!