Hi wondering is it possible to weld round the sides of where the banjo bolt connects on a brembo brake caliper , mines has corroded at the sides , then have it milled flat or is that a definite no no , cheers guys
Personally (for use on my own track car etc)
I would not say that needs a repair.
Apart from the fact that it's probably caused by leaking brake fluid!
If the banjo/fitting was seating correctly and tested for leaks then I would be filing the mounting surface flat enough to seal up nicely with a copper washer.
Then use a stainless wire brush in a dremel to clean out any corrosion then repaint it.
Make up a simple test rig with the next size down master cylinder you have fitted and test it a load more pressure than it will ever see in use.
If it looks worst in the flesh than it does in the photo you could see what the internal spacing was and possibly even put a longer banjo fitting in with a locking nut internally
If there's plenty of thread engagement then mill flat as Toomany says. You can always put a small spacer under the banjo if you need to realign the locating peg.
Fine to machine the surface flat to get a seal, I have seen them a lot worse than that and unless you want to re-seal the calliper don't go anywhere near it with heat.
Is this a Subaru STI caliper??
They seem to be made of non a very good alloy quality.
If you send them out to a company for milling the boss flat I would also ask them to helicoil/timesert the actual caliper mounting holes as well, they are known to strip very easily.