jmabarone Posted March 15, 2022 Report Share Posted March 15, 2022 (edited) I sent a message to the Tech Help desk and haven't gotten a response (might have gotten missed, not complaining), but I thought I might ask for other peoples' experiences. Per the rule book, the required material for rear and side windows is clear polycarbonate material, 1/8" thickness minimum. Since the Rony, Lexan is stupid expensive now and I can't get any at a Lowes or Home Depot within 100 miles right now. So, my question is this: is strictly polycarbonate material required, or can an acrylic plastic be used? Same thickness, same strapping, blah blah blah. EDIT: I know the highs and lows of each material, I am merely asking of legality. Thanks, Jake Edited March 15, 2022 by jmabarone Quote Link to comment Share on other sites More sharing options...
ross2004 Posted March 15, 2022 Report Share Posted March 15, 2022 You'll likely end up regretting the acrylic anyway. Buy once, cry once (and cut once). Quote Link to comment Share on other sites More sharing options...
hotrod Posted March 15, 2022 Report Share Posted March 15, 2022 Lexan will easily crack. Could crack just by drilling a hole in it. Polycarbonate is surprisingly durable. Take car of it and it will last a long time. Quote Link to comment Share on other sites More sharing options...
tommytipover Posted March 15, 2022 Report Share Posted March 15, 2022 Just now, hotrod said: Lexan Acrylic will easily crack. Could crack just by drilling a hole in it. Polycarbonate is surprisingly durable. Take car of it and it will last a long time. FTFY, Lexan is a GE trademark for their polycarbonate . 2 Quote Link to comment Share on other sites More sharing options...
Team Infiniti Posted March 15, 2022 Report Share Posted March 15, 2022 Skip covering the windows? Quote Link to comment Share on other sites More sharing options...
hotrod Posted March 15, 2022 Report Share Posted March 15, 2022 6 minutes ago, tommytipover said: FTFY, Lexan is a GE trademark for their polycarbonate . It's my understanding that Polycarbonate is 3 times stronger than Lexan. Quote Link to comment Share on other sites More sharing options...
kevinatfms Posted March 15, 2022 Report Share Posted March 15, 2022 Acrylic can crack with pressure and shatter. Polycarbonate is supposed to deform and does not shatter. That is how it was explained to me. 1 Quote Link to comment Share on other sites More sharing options...
mhr650 Posted March 15, 2022 Report Share Posted March 15, 2022 On the windshield there is a note that acrylic is specifically prohibited, but the side and rear windows don’t have this note. I suspect that tech will default to not allowing acrylic since the rule only says polycarbonate, and acrylic is significantly less safe since it can fracture. Quote Link to comment Share on other sites More sharing options...
mhr650 Posted March 15, 2022 Report Share Posted March 15, 2022 4 minutes ago, hotrod said: It's my understanding that Polycarbonate is 3 times stronger than Lexan. You are confusing trade names with materials, Lexan = polycarbonate, the popular trade name for acrylic is Plexiglass 1 Quote Link to comment Share on other sites More sharing options...
jmabarone Posted March 15, 2022 Author Report Share Posted March 15, 2022 3 minutes ago, mhr650 said: On the windshield there is a note that acrylic is specifically prohibited, but the side and rear windows don’t have this note. I suspect that tech will default to not allowing acrylic since the rule only says polycarbonate, and acrylic is significantly less safe since it can fracture. Yeah, that is exactly how I was reading it. Looks like I will be sourcing some Makrolon Lexan plexiglas...polycarbonate 1 Quote Link to comment Share on other sites More sharing options...
mhr650 Posted March 15, 2022 Report Share Posted March 15, 2022 When I did my hatch and rear windows, I bought a full sheet from a local sigh shop, cheaper than online and no shipping. If I had it to do over again, I wouldn’t use any plastic for the rear quarter windows, I would just weld some thin sheet metal over them and call it repurposed. when you have a driver strapped in with a HANS the rear quarter windows are completely useless. And since I have my fuel filler in the quarter window, I discovered that while polycarbonate is strong and tough, it is not fuel resistant, I had to cut a big patch out and replace it with metal. Quote Link to comment Share on other sites More sharing options...
Technical Advisory Committee Chris Huggins Posted March 15, 2022 Technical Advisory Committee Report Share Posted March 15, 2022 (edited) Rules: No, acrylic is not approved for the rear window, as that would be directly in violation of rule 9.3.2, unless I am misunderstanding something? You should call local sign shops, last time I bought a full sheet (5x10) for $125 Edited March 15, 2022 by Chris Huggins Quote Link to comment Share on other sites More sharing options...
jmabarone Posted March 15, 2022 Author Report Share Posted March 15, 2022 27 minutes ago, Chris Huggins said: Rules: No, acrylic is not approved for the rear window, as that would be directly in violation of rule 9.3.2, unless I am misunderstanding something? You should call local sign shops, last time I bought a full sheet (5x10) for $125 Thanks Chris. Like Mike, the specifics regarding NOT using acrylic for the windshield but not for the rear windows made me question if it was an oversight or just copied language that was somewhat vague. Quote Link to comment Share on other sites More sharing options...
mhr650 Posted March 15, 2022 Report Share Posted March 15, 2022 Here is another tip for you. If you have 2 stock back glasses, you can sandwich the polycarbonate between them and use heat to form it to shape. In my case since I use my turkey fryer, I guess that makes me a redneck….. 11 Quote Link to comment Share on other sites More sharing options...
Grufton Posted March 15, 2022 Report Share Posted March 15, 2022 1 hour ago, Chris Huggins said: No, acrylic is not approved for the rear window, as that would be directly in violation of rule 9.3.2, unless I am misunderstanding something? Strictly speaking, 9.3.2 does not disallow acrylic, it only states that it wouldn't be free. That said, I assume Tech would (justifiably) throw you out on your head if you ask for a value. Quote Link to comment Share on other sites More sharing options...
Technical Advisory Committee Chris Huggins Posted March 15, 2022 Technical Advisory Committee Report Share Posted March 15, 2022 22 minutes ago, Grufton said: Strictly speaking, 9.3.2 does not disallow acrylic, it only states that it wouldn't be free. That said, I assume Tech would (justifiably) throw you out on your head if you ask for a value. Thats a good point, I will take that feedback back for 2023. Quote Link to comment Share on other sites More sharing options...
frankrehnelt Posted March 15, 2022 Report Share Posted March 15, 2022 (edited) Lexan is a polycarbonate. Acrylic or acetates will crack very easily aka plexiglass. Go poly. Edited March 15, 2022 by frankrehnelt Quote Link to comment Share on other sites More sharing options...
DEE DEE Posted March 16, 2022 Report Share Posted March 16, 2022 5 hours ago, Grufton said: Strictly speaking, 9.3.2 does not disallow acrylic, it only states that it wouldn't be free. That said, I assume Tech would (justifiably) throw you out on your head if you ask for a value. Sure it's pretty clear that ONLY polycarbonate is allowed. Quote Link to comment Share on other sites More sharing options...
DEE DEE Posted March 16, 2022 Report Share Posted March 16, 2022 5 hours ago, Chris Huggins said: Thats a good point, I will take that feedback back for 2023. While your at it Chris take 9.3.3 and clean up that wording also. Quote Link to comment Share on other sites More sharing options...
Technical Advisory Committee Chris Huggins Posted March 16, 2022 Technical Advisory Committee Report Share Posted March 16, 2022 2 hours ago, DEE DEE said: While your at it Chris take 9.3.3 and clean up that wording also. Delete the word “polycarbonate” and replace with “non-oe”? Quote Link to comment Share on other sites More sharing options...
jmabarone Posted March 16, 2022 Author Report Share Posted March 16, 2022 11 hours ago, DEE DEE said: Sure it's pretty clear that ONLY polycarbonate is allowed. No, it states that only clear polycarbonate material is allowed at no value-add. I'm not trying to rules lawyer here (I just want to get through tech and race without wasting money) but there is enough cloudiness in that rules language that a few other people in this thread have agreed with it...and a few more have disagreed with that reading. 9.3.4 states that we can use any plastic to replace the rear window in specific situations. I agree on the merits of Polycarbonate vs. acrylic, merely trying to get what I could find readily and at a reasonable cost. Found a new source, so I ordered my polycarbonate material last night. Thanks for the help and the notes Chris! Good to see you guys are working to keep refining the rules. 1 Quote Link to comment Share on other sites More sharing options...
DEE DEE Posted March 16, 2022 Report Share Posted March 16, 2022 10 hours ago, Chris Huggins said: Delete the word “polycarbonate” and replace with “non-oe”? Polycarbonate is fine. Straps to secure the window to the "chassis or roll cage" My car falls outside this rule, my window is secured to the body. I would say it's nearly impossible to secure the straps to the chassis or roll cage in any car. Quote Link to comment Share on other sites More sharing options...
Hillar K Posted March 22, 2022 Report Share Posted March 22, 2022 Lexan, Palsun, Tuffak, Makrolon are all trade names for polycarbonate. Then there are bullet resistant, abrasion resistant, flame retardant, multiwall, and a few other types of polycarbonate. Quote Link to comment Share on other sites More sharing options...
Administrators Bill Strong Posted March 22, 2022 Administrators Report Share Posted March 22, 2022 We had a rollover at Willow Springs last year and he used plexiglass for the back window of his EC classed BMW. It broke into very sharp shards. Quote Link to comment Share on other sites More sharing options...
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