If the data is accurate I'm glad I went with poly over acrylic:
poly comparison with acrylic.JPG
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If the data is accurate I'm glad I went with poly over acrylic:
poly comparison with acrylic.JPG
When did I say or indicate in any way that I did that? I’m commenting on that chart showing the strength of those materials. They compared ¼” of one to ¼” of the others. If the properties change unexpectedly at other thicknesses my bad. Not meant to offend, there’s nothing wrong with Acrylic, same as there is nothing wrong with glass. I’m just pleased with my choice.
No offence taken. The comparison you posted compared materials of the same thickness. I only assumed that you were able to use 1/4" poly for the same application.
I primarily went with the 1/4" acrylic due to the fact that it could be properly formed in the same shape as the glass that came with my Mk4. My windshield is as rigid as was my glass windshield and I get zero deflection at any speed.
I do understand that poly is quite able to absorb much greater impacts but I was not happy with the properties of 1/8" Lexan when exposed to vibration and high wind forces. While the acrylic is not as strong as poly it is stronger than the FFR glass and with the hardcoat just as scratch resistant.
As I stated when I updated this thread, my intent was not to argue the benefits of one vs the other. It was just to offer an alternative.
F5R #7841: Anniversary Edition MK4, Ford Racing 427, Edelbrock EFI, Gas-N Pipes, Stainless Headers, TKO600, 3.31 Moser 3-Link, 17" Halibrands
Understood. Thanks for the clarification. I do see the advantages of acrylic, but my concern with doing anything not approved by the DOT is why is it not approved? And what is the risk? That’s why I have been interested in discussing the merits of each. I’m still not totally convinced that Polycarbonate is the material you want in the windshield in a crash. I did finally base my decision to install polycarbonate, over DOT approved safety glass, on the fact that polycarbonate is what is used in racing. Beautiful car you have there, by the way.
I just joined the broken windshield club. Car sitting in garage a week with no crack. Developed overnight. No screw mounts or rock strikes so another bad windshield. Any update on sources? I'd like to go with Acrylic or polycarbonate like others rather than glass. Prefer cut and formed ready to go. Looks like Fast Freddy has been well rated but it also looks like he quit selling a few years back.
Last edited by Scottmillhouse; 08-30-2020 at 07:42 PM. Reason: updated
2007 MK3 Roadster, Ford 302, TKO 500, IRS
Cobra sold and ordered a Porsche that sank with the Felicity Ace- now 2 miles below the Atlantic
Still no car- should have bought a top and kept the Cobra
Yes, I have built 4 airplanes and cut the bubble canopies on all but the bubble blanks to cut and fit were heat formed and of aircraft quality so they were a known. Don’t want to reinvent the wheel or use a material with inferior optics and have to redo.
2007 MK3 Roadster, Ford 302, TKO 500, IRS
Cobra sold and ordered a Porsche that sank with the Felicity Ace- now 2 miles below the Atlantic
Still no car- should have bought a top and kept the Cobra
Sadly, I'm in the same club with exactly the same circumstances. Walked out into the garage after several days and there it was. Broken. I needed a quick turnaround so ended up getting the glass only from Factory Five which was easy enough to change and paid for by my insurance. Has been OK since. Found out at the time that Fast Freddie, who used to supply a pre-cut polycarbonate substitute, didn't offer them any longer. After some research, decided if I did go polycarbonate it would be Optic Armor. Others have said it's a generic product that's available cheaper elsewhere. Could be, but still an option. Can buy direct, but they charge shipping and not cheap. Free shipping at Summit. https://www.summitracing.com/parts/oaw-24x72-3. A local buddy installed this exact material in his Mk4 Roadster. Said it was easy to cut with a saber saw. I've seen the result and looks perfect. I wouldn't hesitate to go that direction if necessary in the future.
Build 1: Mk3 Roadster #5125. Sold 11/08/2014. Build 2: Mk4 Roadster #7750. Sold 04/10/2017. Build Thread
Build 3: Mk4 Roadster 20th Anniversary #8674. Sold 09/07/2020. Build Thread and Video. Build 4: Gen 3 Type 65 Coupe #59. Gen 3 Coyote. Legal 03/04/2020. Build Thread and Video
Build 5: 35 Hot Rod Truck #138. LS3 and 4L65E auto. Rcvd 01/05/2021. Legal 04/20/2023. Build Thread. Sold 11/9/2023.
From what Freddie told me way back when he originally did this, and from what I understand reading here since, the 1/4 inch Lexan is too stiff so it tries to straighten out the soft metal glass frame. That's why he used the 3/16. Apparently some have noticed it can flex at higher speeds but most I see mention somewhere in the 80+ MPH range. Also from my experience w/ a rear window for my APE hardtop, it may flex but it definitely will not break. Lexan can actually be bent in a sheet metal brake. In totally unrelated products I have seen 90 degree bends.
FFR MkII, 408W, Tremec TKO 500, 2015 IRS, DA QA1s, Forte front bar, APE hardtop.
I found out Optic Armor makes a polycarbonate 1/4" that is cut and heat shaped to fit our Roadster windshields rather than the thin flat sheet they make as sold by Summit. Cost is pricey compared to glass at $520 plus $50 shipping but Hagerty Insurance was fine with replacing the glass with it
2007 MK3 Roadster, Ford 302, TKO 500, IRS
Cobra sold and ordered a Porsche that sank with the Felicity Ace- now 2 miles below the Atlantic
Still no car- should have bought a top and kept the Cobra
Very interesting. Don't see it on their website, but maybe I'm missing it somewhere. Agree 1/4 would be better. But not as a flat. I assume you're proceeding with it? Post more details and your experience with the installation. I'm sure many, including me, would like to see/hear more about this option.
Build 1: Mk3 Roadster #5125. Sold 11/08/2014. Build 2: Mk4 Roadster #7750. Sold 04/10/2017. Build Thread
Build 3: Mk4 Roadster 20th Anniversary #8674. Sold 09/07/2020. Build Thread and Video. Build 4: Gen 3 Type 65 Coupe #59. Gen 3 Coyote. Legal 03/04/2020. Build Thread and Video
Build 5: 35 Hot Rod Truck #138. LS3 and 4L65E auto. Rcvd 01/05/2021. Legal 04/20/2023. Build Thread. Sold 11/9/2023.
I haven't experienced any deflection of the windscreen at speed and after 3500 miles there are a few nicks like you get in glass over time, but no scratches at all. I do use the Plexus plastic cleaner on it, but no special treatment other than that. I’ll definitely go this route again when the time comes.
Fast Freddie is still trying to get another batch made. This was the last update I received in April of this year.
Hey guys, I just wanted to give a quick update. We have been trying to source new lexan material to get these windshields made already and the prior supplier only has lexan that we would not pass due to imprecations in the lexan that we would not allow. We found other suppliers but they required a 46 sheet minimum, which is a $30,000 investment in just material and a ton of windshield. We are now looking into a 3rd option where we can most likely get quality material, but they are much smaller sheets, so instead of 7 windshields cut out of one sheet, we may now only be able to get 2 shields out of a sheet. Hopefully we will get some more info on this being an option earlier this coming week. It may make the cost a little higher but we will try to hold to a reasonable price.
MK4 - complete kit - Blueprint 427W - Holly Sniper EFI - TKO 600 .64 - 3.55 3 link - 17" Halibrands
Response from Fast Fredie "At the moment they are out of stock with no ETA. I would recommend you find a different source other than us as I'm not certain if we will be able to get them made again, or any time soon. Thanks for the inquiry" This response was today 31 August 2020.
2007 MK3 Roadster, Ford 302, TKO 500, IRS
Cobra sold and ordered a Porsche that sank with the Felicity Ace- now 2 miles below the Atlantic
Still no car- should have bought a top and kept the Cobra
Count me in for the "cracked windshield" club...in 2015 went away for a month with car in garage with cover on it. When I got back, removed the cover and windshield was cracked?
FFR did not have any windshields available at the time but fortunately Fast Freddie's was offering the Lexan windshield so ordered one and installed...fit fine without issue.
5 years later I have had no problems or issues, I am careful about cleaning bugs/debris from it using lots of window cleaner and microfibre cloths. Scratching or haze has not been an issue although i must admit that have only been caught in the rain twice and RainX (for plastic) works great for clearing rain (in other words the wipers are basically hood ornaments).
As has been pointed out in previous posts, plastic (polycarbonate or acrylic) will not pass a provincial or state inspection so initial inspection (or annual inspections if required) will need a glass windshield unless "you know a guy".
Personally I would not use acrylic as it does not have the same impact resistance as polycarbonate, race sanctioning bodies (e.g. NHRA) require polycarbonate. While more expensive it is much safer if a rock hits your windshield at high speed.
There are so many posts about our focus on safety with these cars with flywheel scattershields and driveshaft hoops (both NHRA requirements) I find it hard to believe that using acrylic is even a consideration.
Just my 2 cents (Canadian), about a penny US.
Dave
Mk IV, 347 AFR heads, WC T5, Solid Axle 3.73
I finally installed the Optic Armor Polycarbonate windshield. It was heat formed to the correct shape but was oversized by 1/2 to 1" as compared to the glass. Once glass was removed just cut to shape with a fine tooth blade on a saber saw and carefully sanded the edges smooth and slightly beveled them. Reused the glass rubber strip but had to use a lot of spray silicon lube to get the plastic and rubber gasket in the stock frame. Reinstalled assembled windshield with it fitting the same as the glass. No worry for cracks now.
2007 MK3 Roadster, Ford 302, TKO 500, IRS
Cobra sold and ordered a Porsche that sank with the Felicity Ace- now 2 miles below the Atlantic
Still no car- should have bought a top and kept the Cobra
I see Optic Armor recommends using their glue to hold it in place. Did you use any, or just trust it won't pull out of the seal?
http://www.opticarmorwindows.com/fre...-questions.asp
Just saw this. No glue since I used the glass weather strip. That actually is a rubber channel. Since poly was cut to size it is completely framed so unable to move. I believe adhesive is for when you do not use channel. That actually would have been a lot easier than working the poly and rubber channel into the frame.
2007 MK3 Roadster, Ford 302, TKO 500, IRS
Cobra sold and ordered a Porsche that sank with the Felicity Ace- now 2 miles below the Atlantic
Still no car- should have bought a top and kept the Cobra