Replacing Glass with Perspex

[Glassman]

I've agreed to sponsor a car for a track day (or three) and I'm replacing the windows (E36 compact).

The only time I've used perspex is as a temporary measure (for when the replacement glass isn't immediately available) I'm looking for some advice / tips from someone who has experience of using it on a racing car.

One question that stood out was whether or not the driver side would need venting? Is this advisable, could we achieve it with a few ~30mm holes? Would it put pressure on the back window (also proposing to perspex)?

[stifler]

Iirc they don't particularly like perspex in race cars. They prefer polycarbonate. Although this may be for the windscreen only.(?) But for trackdays you will be fine with perspex.

WRT the rear windows blowing out, if you have a duct or hole to flow the air out of the cabin in the rear side windows you should be ok.

When I ran a BMW M3 GTR at the 'ring we had a roof vent that blew a lot of air in, the car had standard E36 pop out side windows. These stayed open all race and we never had any problems with pressure build up in the cabin.

[frodo_monkey]

Perspex generally isn't used in racing cars because when it shatters it breaks into razor-sharp shards which could be pretty lethal if flying around the cockpit. Polycarbonate is better (much stronger) although is less scratch-resistant. Plastics4Performance (Google them) make something which is said to combine the best of both worlds, but I've not tried it. Convention is to use 4mm for racing and to vent I would suggest either holes or making a slider (easy to do).

[Glassman]

Thanks guys.

Whatever the material ends up to be, I'm planning to coat the rear windows with PWF (perforated window film) which looks slightly tinted on the inside but shows graphics from the out...