Three screws should do it. Tap it lightly with the handle of a scewdriver. Should pop right off. What you seem to be describing is the rotor drive bracket which is attached to the end of the camshaft. You do not need to remove this part to change the rotor. You've already got the part you want removed, i.e. "the middle part".
1987 BMW 325
[This message has been edited by jeffsr (edited 06-12-2000).]