When I mounted my wind wings, I drilled the post right on the car. Never took the w/s off. Just be careful. If that's what you're trying to do, it can be done. If you use the existing c/l of the four screws that hold the frame to the post, you won't go wrong. Use the correct drill (start small first) for the thread you are going to tap. Then drill just through the side post. This is only about 3/16" so you can put a piece of tape or rubber hose over the drill to limit your depth. Next tap the hole. Use air to clean it out and mount your wind wing block. Or, you can do it the other way and just drill through the post behind the w/s and put a nut on it. Yuck!