I had heard that a good way to keep my door speakers from rattling is to spray some foam sealant (like Great Stuff) around the speaker in the speaker hole. Is this safe? Has anyone else tried this? Are there other ways to stop the rattling?
Its safe (and cheap) as long as you use it correctly. It expands a huge amount, and this process doesn't happen in just the time it takes you put it in. It keeps growning for minutes, meaning if you put too much foam in a tight space like a door, you'll be heading to the junk yard for another one.