I've been having this problem with my '98 S70. It develops severe chatter in the front brakes when they get hot, it's hot out, and are used on hills, although I also had it happen after the car had been sitting all day while I was skiing. It's a "buzz" chatter, not an oscillation or cyclical pattern. The whole car vibrates and the noise can be heard outside the car. Once it starts, it happens on the flats, going up hill, etc, until the brakes cool. I've been taking it into the dealership for almost a year now for this problem and because they have been unable to duplicate the problem during their "6-8 mile test drive" they haven't fixed it. I was told that unless I wanted to pay for them to do additional testing they can do nothing unless they experience it. Have any of you experienced this? If so, have you had resolution? What is causing this? The first dealership thought it was the rotors and replaced them at 18,000 miles in 8/99, the rear rotors were replaced again at 26,000 in 6/00. Any insight would be greatly appreciated. This is my family's 5th Volvo (my father leases). It comes off lease at the end of April and I'm thinking of buying it, but don't want to if they can't fix the problem and if this is the kind of service I'm going to receive.