With the NASCAR style doorbars of the cage and me not thinking far enough ahead I have to run bolted in polycarbonate (PC)/lexan/makrolon…it’s all the same… door windows. Unfortunately the door bars stick a little too far in for me to keep the rails to roll the windows up and down.
Looking online at various places I realized people want an arm and a leg for these things; around $500 after it’s all said and done. Having access to a large oven and some free PC drop material I decided to make myself a set to save some money. Note that large box stores sell PC sheet for a decent price if you have to purchase some and for a miata you'll have plenty of material for a couple sets.
Below is a rough outline of the steps taken to form, trim, and fit the PC door windows.
PC scratches VERY easily and is a pain in the ass to polish out. Keep the protective film on there for as long as possible and reuse it when not forming or when you're trimming to size post forming.
Using your CLEANED OEM glass as a mold, place the PC onto the glass and clamp to the bottom edge of the glass. Protective film of course needs to be removed for this. PC piece should be a little larger than glass size.
Set the clamped glass and PC in an over and support in a way that allows the PC to “fall” onto the glass without obstruction. The forming temp of PC is 300-500 deg F depending on supplier, thickness, desired shape.. start low and see how it looks before increasing temperature. For these it was 310F for 5ish minutes.
once the PC forms to the glass, turn the oven off and let it cool. Once cooled, remove the PC/glass making sure to not shift anything. Using a sharpie, trace the glass outline on the PC. I then removed the glass and reapplied some protective paper to the PC. After BOTH sides have been re-papered, place the glass back onto the PC and line up with the sharpie marks. Re trace the glass and mark onto the paper with sharpie.
Cut the PC to shape using a jigsaw or band saw. Use a sander and smooth out/roll the edges.
Install into the car and match drill as required. Install with longish bolts and an assortment of nuts so you can "push" the bottom of the window out and create a good seal at the trim. I also added a strap that attaches to the door and the top of the window to "pull" the window in to get a better seal.
