Polycarbonate windows in hardtop

[djw090]

Currently I have a hardtop for my MGB that has glass side and rear windows. I use the car in sprinting the rules do not restrict what I do to the hardtop. My plan is to replace the glass windows with ones that I will make from polycarbonate (perhaps lexan to some of you). The windows will be glued in useing a PU type sealant but I may use some screws as well. The question in my mind is what thickness to use. I have an offcut of 3mm polycarbonate that is big enough to do the 2 small side windows. So my main concern is the rear window. I want to keep the weight down but it needs to be stiff enough not to act like Rolf Harris's wobble board. So anyone know what thickness to go for?

[BlownMGB-V8]

My Parish Plastics hard top uses 1/8" Lexan for the wraparound rear window.

JB

[djw090]

Thanks Jim.
From the pictures I have seen of the Parish hardtop the back window has alot more curve to it than mine. While my hardtop is not a works one the back window is very similar.

[WedgeWorks1]

I know many racers here in the states with a lexan rear window will put aluminum strips to keep them from coming out and make them rigid. Sometimes the strips are required.

[tr8todd]

SCCA rules dictate a 6mm front screen and 3mm for sides and rear screens.  From personal experience, 3mm will buffet in the wind unless you brace with 3/4" X 1/8" aluminum straps.  If you plan on using a preformed gasket that secures the glass, I would suggest using lexan the same thickness as the original glass.  You can form the lexan by gently heating it and securing it to the glass window with spring clamps.  Takes patience to slowly heat it to 300 or so degrees.