So my Octavia since yesterday had been making a rattling noise, from turning the music off and locating the problem to the drivers side front, on closer inspection it looked like the guard behind the brakes had moved and you could see marks on the inside of the alloys from it too, tried to get in to see if it was loose and it was and then as I was not home needed to make it safe to get home, managed to get it out and well I’m amazed looked like something has happened 

All I can think of is stone damage but it would have been a hell of thump and you'd have been aware of it.

2 hours ago, ntl123 said:

So my Octavia since yesterday had been making a rattling noise, from turning the music off and locating the problem to the drivers side front, on closer inspection it looked like the guard behind the brakes had moved and you could see marks on the inside of the alloys from it too, tried to get in to see if it was loose and it was and then as I was not home needed to make it safe to get home, managed to get it out and well I’m amazed looked like something has happened 

 

Must've been something substantial. Three cut outs are where the bolts that hold it on are located. Seen them rust off before, but your back plate looks nowhere near that stage.

I know I’ve definitely not heard anything as substantial, only thing I can think of was last night went to a restaurant and the car park there was as bumpy was it could be so maybe that had something to do with it? Other than that I have no idea, all I know is I now need a new guard, very strange 

Lucky that it did not detach when driving. Better also check the other side. Good luck with that.

As they thin with rust often the bosses around the fixings will fatigue fracture but still hold in place, I would say that 2 of yours had already fractured and the 3rd which can be seen deformed in the photo broke when you impacted something, it would have fatigued anyway.

 

Replace the other side and check the rears as well, I thought I only needed to replace one of mine which was rusted through but all the others were like yours, dead cheap to change, cost about €15 the pair.

In the picture, corrosion doesn't look to be a problem.  If it is, how old is the car so we can then think about replacement at given intervals.  If two of the bolt holes had already let go, it could well be, as J.R. thinks, a bump or one of these half humps they keep putting in the roads caused it.

No sign of rust, it’s clean which is even more strange you can see shiny metal around where it’s sheared so I’m so confused, my cars a 63 plate elegance model, done 75k miles