This one has me and all my mechanical friends (well, you know who I mean!) baffled. My 240 only does this after a few hours of highway miles. It makes a gawdawful screeching sound from somewhere in the drive train - I suspect the rear axle assy. Noise often goes away when I touch the brakes, but not always and seldom for long - the only thing that stops it completely is ending the journey. After which it doesn't do it for months of around-town, or on the way back home after a few hours of highway running. Suggestions have been dry dif (no), rock trapped twixt disk and dust cover (no) - but that certainly sounds about right. I've about given up, but it's too loud a noise to ignore - turning stereo up to max won't cover it. Any suggestions appreciated, signed hopeless.