I used to drive an old Allegro and one night there was an alarming loud knocking noise everytime I turned left. It sounded just like somebody knocking on the car door. Spooky! Panicking, I found a garage that was open and after checking the engine, all the bearings, etc., the mechanic said he could find nothing wrong - except maybe it might help if I took the can of WD40 out of the glove compartment.