Ok I know i should know this but looking to change cambelt and tentioner on 1.4 corsa premier (96) What is the bolt on the crankshaft pulley A star or torx head or is their no difference. I ask as im try to find out what size it is to buy said socket. I did try with ordinary socket set and although it seemed reasonable fit was rubbish and skinned knuckles later think should get real tool.