Hi. I wanted to take the break disc off on one of the back wheels, but it seems to be locked with a couple of screws which an allen key would remove. I think there were more screws, but aren't there. The issue is, an allen key won't fit properly as where it goes is rounding. How can they be removed in this case?

You can break the heads off rounded Allen screws by just hitting the back of the disc with a hammer.  

Then you have the option to remove the stubs using mole grips or drill them out.  Or just leave them off, the wheel bolts hold the disc in place anyway.

Ah. I thought the stubs kept the discs in place also. If not, what are they used for?

They stop the disc moving about when you remove the wheel.

Nice to have, but not an absolute necessity.

Modern fiestas don't have any screws holding the disc in place (mine doesn't) they rely on the wheel studs and nuts to hold in place when wheel on. As said above it's not essential if you have them anyway.

BTW if an allen (hex) key doesn't fit, did you try a Torx key/socket? A lot of modern cars use these Torx (star shaped) fittings, not hex. 

I had already given up. I didn't want to damage it any further. I think it's too rounded for anything to use. Glad to know it's not needed to take the disc off. Thinking about it, I think I asked the last time and forgot. 

It's going to get booked into the local garage soon now, but thanks all as it will help for next time.

 

Decided to pop to the tyre place and they changed the nut. They just hammered their wrench on. I didn't check if the nut came out the wrench ok as this was a concern for me trying it in case it got stuck. 

£3 to get it changed and less anxiety for time being.

So just to be clear, the two parts circled do not need to be removed to remove the discs? One fits ok with an allen key but seems impossible to remove.

Those are torx bolts. And yes they do need to be removed to remove the brake drum( not disc.) quite often they stick and torx rounds off on the bolt. Then it's a case of a pin punch and hammer to loosen them off. Then if the drum is still stuck on, screw a bolt in to the threaded hole on the right of drum in the photo. 

Pin punch and hammer the drum or the bolt?

What would tou do with the screw once threaded? 

They are definitely Torx heads and you should not try to use a hex key on them. I would use the correct size Torx and an impact wrench to remove them.

7 minutes ago, Paulius55 said:

I would use the correct size Torx and an impact wrench to remove them.

I agree, but looking at the state of them now it might no longer be possible. As a last try effort I'd use the correct size torx bit and fit it to an impact driver. At least then when you hit the impact driver with a hammer the torx bit will be brayed in to the head of the screw with less chance of it camming out.

Example: https://www.screwfix.com/p/hilka-pro-craft-impact-driver-set-13-pieces/7257R?tc=LH2&gad_source=1&gclsrc=ds

Pin punch and hammer to tap the bolts anticlockwise of there tapered seating then you can unscrew the by hand. Buy some aftermarket replacements off eBay with Allen key type.