I have a theory that the screens are susceptible to cracking when subjected to rapid changes of air pressure, the screen on my 4/4 Sport cracked when I was stationary in traffic and a large truck coming from the opposite direction swooshed past at 60 mph, the wind blast rocked the car and 1/2 a mile down the road I noticed the start of a crack. A member of the Warks MSCC started his BSA 500 single cylinder motor bike and cracked the screen on his Roadster parked a few feet behind the bike........just a theory, not easy to prove beyond doubt
