Dude ... you remove the collar. Its function is to ensure the shaft is secured when the prop is on the can. Do not drill the mounting. Then you will need the same collar at the back of the motor to hold the bearing in place. Look at my photo some where in this thread. The back has a plate that secures the rear shaft. It has a bearing. There will be a space of about 6mm between the bearing and the gold protrusion, that needs to be filled so the bearing stays in place. I used the same collar but its not tightened, used it as a spacer.