Caulk

I loosened all the screws on my rear window and forceda small amount of caulk (forget the name, recommended in earlier posts) between the Lexan and the frame. I took each screw out (one at a time and Hhaven't had a major spill yet so I don't know if it's working but it seemed like a good idea. The caulk does have to be compatible with Lexan.

Wayne 120241
 
My Ercoupe uses a small rubber channel, u shaped piece you just slip on the outside edge, seals air and rain as you snug up the bolts. Seems to work plenty well.