AberdeenBikers

was trying to get the caliper off my front left fork but the allan bolt not budging.. i don't want to farce it to much just incase i round the allan bolt... has any1 got any ideas what to do or use help to get it undone without damaging the allan bolts heads holding the caliper to the fork

Soak the bolt overnight in a release oil. Note that although WD40 is a relaease oil, it is a multipurpose lubricany as well. Possibly a dedicated release oil will be better.

Next morning use an impact wrench.

Good luck.

Borrow a set of Allen headed sockets sa these are less likely to round out the head of a bolt IMHO
also get some good qulity penetrating oil like Omega (WD40 will do ) and let it have a good soaking.

Obviously you dont want to get it on your pads, but if you are ditching them then it is no big deal.

If you get it on the disk make sure that you give it a good clean prior to re-assembly.

I should have just waited for You to post up what I was thinking

Halford usually do 3 for 2 on wd40 and stuff. Recently got penetrant spray which has been a Godsend for getting rusted nuts and bolts off. The neighbour with a grinder and metal cutting discs also came in useful!

Soak with a release oil.

Allen headed socket, as said above...place in the hole, making sure it is a very good fit, and then tap with a hammer...not hard but enough to make you feel like a man!

Then undo..should come out sweet as a nut.

Important to get allen socket that is a tight fit. Sometimes it is worth using an imperial sized one as they are a slightly different size and fit much snugger.

will try over the few days and see how i get on....

Personally I would not be hitting anything thing with a hammer or impact driver unless you can support the back of the bracket. The weakest link there is always going to be the mounting bracket. I would stay away from Imperial too. Just get a good quality allen socket

Shrek,
Its a last resort if all else fails

Sometimes the allen head corrodes slightly, therefore openning up the hole a tiny bit which means a Metric does not fit snuggly. Again, extreme case.

And like I said, no need to hit it hard, just a forceful tap does it...as a last resort :)

As a last resort before drilling out I've used a star security bit gently hammered into an allen headed bolt, they grip quite well.....

Have you tried switching it off then back on again?

A little heat may help