What's caused my F650Gs's brake disc to warp?

Q. I have a 2008 BMW F650GS, which I bought last June with 1900 miles on the clock. BMW replaced the front disc under warranty, saying it had becomewarped. Although no reason was given to why it may have warped (only that it was unusual.)

The bike has now covered 7800 miles, but just failed its first MoT due to another warped front disc. BMW will replace the disc under warranty again, however they still cannot tell me why it has warped.
Cjseach, MCN forums,
 
A. You may have to educate your BMW dealer who keeps on replacing discs on your bike. Your bike has a floating caliper, which needs to slide on the caliper hanger to centralise itself as the disc is not a floating type disc.

If this is getting stuck or worse, seizing, then the caliper pistons and pads will push on thedisc, bending it, instead of centralising it so that the pads clamp both sides of the disc evenly.