theres a guy on here who opened up the dropout on a steel 456, I'm sure he'll be arround in a bit, maybe start a new thread with "bent 456 dropout" in the title?
That's probably me. 🙂 Although it was an 853 Inbred. And it was a LOT worse than that. Mine was so bad the hanger locked the cassette solid!
Firstly, you've got nothing to loose by trying to bend it back. It's not useable as it is, so you might as well try.
Secondly – TAKE YOUR TIME WITH IT!!!! Don't start hitting it with a hammer! If it's going badly, WALK AWAY and try tomorrow!
I stripped the bike down so I could put the frame in a vice, then firstly got the hanger roughly straight. The thing is, it might not want to bend back in the same place it bent in at, if you see what I mean, so you have to be careful to clamp the hanger in the vice, and use the edges of the jaws to get it to bend back in the right place. It's NO USE trying to do it any other way, you risk having an 'S' bend in your hanger!! Seriously!
Clamp the hanger in a the vice, use the frame as leverage.
Then, when it's roughly straight, you need to get the dropout closed up. Again, it might not want to bend back in the same place, so you need to ensure the dropout remanins 'dropout shaped' and not teardrop shaped!
I got an old hub axle and a couple of nuts, which I clamped into the dropout, to use as a 'former' if you like. Then I clamped some molegrips on the dropout, so the jaws were on top and underneath the hanger (Handle pointing backwards) and then turned the frame upside down and sat on it, so I could pull the dropout towards me round the axle, and see what was happening. I also screwed a bolt into the mech thread, so I wouldn't close the hole up as I was bending, or from the molegrips
Like this
Then I used a hanger alignment tool to get it spot on. You can't guess this, just buy the tool, IMO!
End result, burrs filed off, wire brushed clean.
That was 3 years ago now and it's been fine ever since. 🙂