Ive got a -97 A4, 1.6 l. I had to change my rear brake discs, and I discovered to my annoyance that this was umbraco bolts. Needless to say, they were rusted stuck like every other bolt on the god forsaken car, lol.

Ive gave them all a shot. First i used a steel brush to remove dirt/surface rust, then applying rust remover. Still, everyone was so stuck that the umbraco bit just rotated inside the bolt head, without the bolt rotating along. Maybe not so smart to try them all.

Actually, I got 1 bolt to rotate approx 6-7 orbits, and every orbit I had to really struggle. Im a big, strong guy to, just to give you an idea of the degree of stuckiness <--- new word.

I want to do this myself as Im a poor student, and the shops take approx 600USD to change them. Its a really simple task to begin with, so I hate paying others to do it.

Should I just drill them out?
Maybe get a grinder and grind the corners on the round bolt into a shape fitting a spanner/socket? (Ive fantasized obout this option :-) )

Btw, why the hell did they make these bolts umbraco, its downright retarded.

Any reply is appreciated, even the ones stating Im a dumbass for ruining the bolts