The coil overs don't go bad. It's the way the suspension is setup. I think you need to learn more about what a coil over suspension is and then you will find out what goes bad and what doesn't to ask the right kind of question. Also depends on what type and how you have them setup that go into play, kind of use blah blah blah. Probably longer then you'll have the car unless it's slammed to the frame.