never seen something like that..no idea why this happened..

but will effect the brake performance badly, so drive the car slow please until you sort it..

they could have put the wrong pads on, i had that with my front discs, pattern pads had been fitted which meant they did not use the whole disc.

Fitted geniune GM all around at the front, massive difference 

My rear discs looked a lot like that when I changed them

ah Mr 21, good to hear from you, hope your well?

Thanks for replys Gents.
Rest assured, new discs and pads going on. Picked up parts on Monday and the car flashed up the wear warning the following day  . Only one wear sensor on mine.

So what are we saying exactly? That the car has stood for long periods(previous owner. I use if daily) and the discs have rusted causing excess pad wear? Would they "weld" themselves together then rip lumps of pad out when moved? Or just rusty discs is enough on crap pads?

Didnt notice if the old pads where genuine, but the discs had no wording stamped on them as the genuines do....?

Have seen pad marks on other cars discs where the the disc has rusted then leaving a print of the pad on the disc even when the rust is long gone.

Anyway.So nothing too unusual then? My first thought was as Tunnie says, that someones fitted the wrong pads at some point. But then realised that could not be the case as the 10mill area was not being scrubbed, the high area would scrub first when correct size where re fitted, not the low area, the opposite of this....

And by the way, i was considering ebc or similar as a bit of an upgrade, but remembered my old rule about starting from stock with new parts, before condeming the genuine set up. Obviously, having done the rear pads and discs, the improvement  is instant even before they've beefed in fully. Looking forward to getting the front done now

Very typical for rear brakes especially. In lighter cars with rear discs even worse, because rear brakes do not work that much in every day driving. Here, where we have real winters etc the problem is quite common and big, it's a must to clean and grease the brakes at least annually to avoid this. The caliper gets easily stuck and with only light braking the middle of the pad meets the disc and you can see the results in your pics.

The other marks on your discs are also normal. The small pieces falling off from the outer edge is just corroded steel from disc, not dangerous but you must keep an eye on the minimum disc thickness (which is reached quite quickly due to the facts above)

That chip of material missing from the edge of the disk has been on the move for some time, as the pit it has left behind is rusty.

My guess is that the disk started to break up, there was a crack or even a missing chunk there on the outside edge, and that has abraded away the pad material in that section and prevented it making good contact with the rest of the disk.

That leads to uneven heating of the disk which will only make matters worse.

Any sign what make the disks are as I'm wondering if they are poor quality? Then again, at your mileage they may well be original?

Kevin

This seems to be a common problem on replacement Omega disks.

My original set lasted for 40,000 miles, but I have never got more than 15,000 miles from a set since. I have had one set replaced under warranty (after 11 months/9,000 miles), but the Vauxhall Technical Rep reckoned I didn't drive the car enough! 

The front disks on my wife’s Astra have done 65,000 miles, and are in perfect condition (although below the specified minimum thickness).

This suggests to me that the aftermarket disks (i.e. the ones fitted outside of the guarantee period) are not of very good quality.

Edit: I should add, it looks to me as if the outer layer has brokwn up, exposing rough cast iron beneth. I do wonder whether the original disks have a thicker/more durable outer layer than the replacement parts.