Interesting Rotor/Hub problem!..
 

I know it's a crap picture (from a mobile phone), but checkout the picture attached...

what the hell would cause this?, issues with casting or something?.

It's an ATE/Bilstein Rotor from the back of a W114 Mercedes, which was replaced just over 12 months ago (along with the fliexible hoses, and pads). The entire of the internal handbrake was removed from the hub at the same time so nothing would've been flying around inside which is the only thing i could think of.

It has to be the weirdest thing i've ever seen. i'm taking it back to the place i bought it to see what they think. just gotta get the thing off first.

PS. obviously there isn't meant to be a hole there!

wierd. are there any other cracks in the rotor?

handbrake rubbing a bit causing overheating - coupled with a bad casting? A good close up of the edge of the hole will tell you a lot - wether it is crystaline or not...

weird tho'

This appears similar to a thread a while back from Litton (I think) when he investigated a rear brake issue on his 108 and discovered a rotor separated from the hub, spinning free of the hub!

Hello,
Is the car used infrequently? I would check the caliper mount for any *misalignment*. Are the pads worn evenly or *wedged*?
Bad wheel bearing or loose/broken bolt in hub?

it's a daily driver, and those rotors are ATE and just over 12 months old. the internals of the park brake were removed when i put the last rotor on (because it had some issues). The caliper was fine, as were the pads. even on both sides, no rotor warp and the wheel bolts didn't seem to have any problems..

from another forum a brake expert seems to think it's from the casting. a cold spot that has popped out

Impact damage (from either side) will cause a distortion inwards or outwards -- these are fairly heavy, so a knock hard enough to remove a chunk will certainly bend something else.

I would suspect a defective casting.

Peter