My control arm broke in two... yes two pieces ... right down the middle. It was so severely rusted that it must have just snapped when hitting a pothole or some such thing. I drove for many miles though before realizing the problem. I was very lucky I didn't die or at best destroy the car, as many of those many miles were highway. Frankly, my mechanic was shocked that I was able to drive at all like that. Credit to Volvo I guess. If I were you, I would have them checked frequently for stressing or failure. Or better yet, just get a solid used set from a wreckers, have them installed and don't worry about it anymore. Why take the chance?