89 Civic LX Auto

I'm getting a big vibration from the transaxel when it shifts into 2nd. The car is an automatic, and I've kept the tranny fluid changed and everything. If I take my foot off the gas right before the tranny shifts, it shifts with no vibration or sound.

I have a link to the sound I recorded by taking my laptop in the car and taping a mic to the battery. If you listen you can hear the big low sound as the car shudders into 2nd. I am driving the car normally and it shifting at about 2500 or slightly over. I really don't have any other problems besides what you can basically hear in the file. I think I hear valves clattering in the file also.

http://waffleserv.servehttp.com/sound.mp3

Does anyone know why the tranny may be doing this?