Raleigh sxc vs Shimano tigra front brake

Bateman
Bateman Posts: 6
edited August 2013 in Workshop
Hello,

Very much a beginner. I was given an old raleigh sxc road bike frame and I have been doing it up thanks to ebay etc to make it rideable again on the cheap.

Anyway Im trying to fit a front brake, (shimano dual pivot) to the bike. I place the front brake through the front fork and tigten the pivot nut behind it. But no matter what size pivot nut I use, the front brake is never fastened securely and is free to sag and wobble etc. As if the front fork has a larger diameter than any of my pivot nuts to attach to the brake securely.

Anyone got any ideas how I can resolve the problem?
I sound silly for asking but I am a beginner.

Thanks

Bateman