The reason why I’m already placing the weatherstripping and glass in the window frame is because it’s easier to do it when the windows are still off. This gives a better angle on working the weatherstripping in and when you put in the glass, the frame needs to be forced a bit, so the glass will slide in. This is very hard to do when the frame is already fixed to the hardtop.
It is very hard to explain what I did for installing the weatherstripping, so I’ve created a step by step photo report. One important thing to mention, so you will understand what I did, Is folding the sides of the weatherstripping under the middle. You will understand when you see the pictures. This way the weatherstripping is a bit stiffer and easier to cut (like the draining holes and corners). Also getting the weatherstripping into the frame will be much easier.
I used a blunt object like the rear side if a teaspoon, to push the weatherstripping firmly in its place.
You will see an example of cutting the drainage holes and the corners, just like the OEM weatherstripping. I can say, it will cost you some sweat.. and you need to use your fingers a lot to “massage” the weatherstripping in its place, but when its there, it fits like a glove. At the end I place one window at a time in the middle of the frame and force it outwards so the window will slide in.
See the pics for the whole story.