Side Window Material

[Dave P]

I was at the Auto Fair here in Charlotte again this weekend. I have seen another GT40 with really crappy looking side windows. They seem to get very dull or crazed looking. I cannot remember seeing the lexan widows in our late model stock cars looking like that.
Is it choice of materials? Hot southern sun?

 

[Bill Musarra]

Dave,
I think it is just a low grade of plexiglass that has either been flexed and crazed or atempted to be cleaned and the agent attacked the plexi. The stockers and drag guys use a special form of plexiglass, probaly an AN-10. I saw some on a couple of drag cars and it is quite strong. They make them for specific models of cars to fit. I would imagine that for our purposes, it would have to be special ordered.

Bill

 

[Trevor Booth]

quality would be the issue , insist on Acrylic material that complies to ANSI - Z 26.1 grade AS-4 or better, I would not be using lexan, it shatters into shards like glass when it breaks. good quality acrylic sheet performs better than glass in terms of light transmission

 

[Mark Clapp]

The plastic I really like to work with is PETG. It is shatter-proof in that you can fold it flat back onto itself and while it creases, it does not crack. Thus rocks/track debris are no problem and it will not star crack around mounting screws. The plastic trims and drills easily and does not require special drill bits for plastic. It has a terrific luster that looks almost wet as well as being crystal clear. It is great for light covers and windows but not for engine covers as it can not withstand the heat. Lexan is best for that.

 

[Dave P]

With our short track cars we always just bought a windshield blank from the body manufacturer. If I remember correctly they were fairly expensive and had to be.125 thick per rules.

I have seen plexiglass shatter like is described but not Lexan. Were would one purchase acrylic?

Hey the best part of the show was watching guys stand in awe of the 40's being displayed.

 

[Jac Mac]

Yes , I think trevors got them mixed up... perspex/plexi can shatter like crazy, but I have hit Lexan with all sorts of hammers......they just bounce off..

 

[Phil]

Dave:
Any plastic supplier would have Lexan sheets (Polycarbonate is the generic name). I have bent it on a sheet metal brake, and it is possible to heat form it in compound curves. There is a UV resistant polycarbonate available, and also a special cleaner that leaves it rather glossy.
It comes in various thicknesses, and the straight cuts can be sheared without cracking the material. All in all nice stuff.
Cheers
Phil

 

[Trevor Booth]

no I have not got it mixed up.
Polycarbonate (lexan) is harder to break than acrylic but when it does it can be like broken plate glass with very sharp edges. Polycarbonate is not generally acceptable for automotive glazing. For the US it needs to comply to ANSI Z 26.1 for Au/NZ it needs to comply to AS/NZ 2080.

There are 15 or so different grades of lexan , filled, unfilled , reinforced, unreinforced, flame retardant etc. Lexan is a trademark of GE plastics

I might suggest that in the event you use a non complying glazing in your vehicle and someone is injured you may have some explaining to do as to why you used a non complying glazing material.

US CFR 571.205 Is the applicable US law.

 

[Jack Houpe]

I have made side windows for a friend that I cut with my cnc laser out of acrylic and polycarbonate (lexan) I prefer the lexan over the acyclic, the scratch resistant polycarbonate is very expensive but seem to be very pliable and more forgiving that acrylic. Mark Clapp who posted above knows more about this than anyone, he makes windows light covers and other parts for car manufacturers. If he says PETG is best then its best.

 

[Dave P]

Trevor:

Looks like you have done a lot of homework on this subject. Why do you know so much about it?

 

[Tim Kay]

While admiring an original at the Monterey Historics last month I asked the gentlemen working on it where they purchased what appeared to be a very quality looking plastic. He recommended 'Aircraft Windshield of California'. And if my memory serves me, it is located in the LA area.

 

[Pat]

I went with LEXAN MR10 - the MR is Mar-Resistant and the 10 is the 10yr warranty against yellowing due to UV exposure. MR10 is what they use in NASCAR and is sold by a lot of the race car parts suppliers.
A local aircraft parts distributor told me that there are several LEXAN type polycarbonate variants and not all have the same strength and recommeded the MR10. He also said that since it comes with a scratch resistant coating on it, it should be only cleaned with isopropyl alcohol, or rubbing alcohol. Even using Windex is hard on it as the ammonia weakens it over time.
They use the 36mm MR10 sheets at work for bank teller windows. Here's a photo of one that stopped a bullet.

 

[Bill Musarra]

You can find just about any thickness or size you want. Still not cheap:

lexan mr 10, great deals on eBay Motors, Business Industrial on eBay!



Bill

 

[Trevor Booth]

Dave,
I have an interest in a plastics fabricating company and I do all the engineering design , we make security screens for banks out of Lexan , we have in the past made security screens for taxis. I have been involved in plastic fabrication for about 13 years.

WE conducted the world first crash test with a type 3 dummy in the rear seat to demonstrate the crash worthiness of a taxi security screen and passed first time, I used acrylic sheet , our opposition used Polycarbonate, we got the government contract !!

Certainly polycarbonate has some advantages over acrylic, however, you are dealing with legislative requirements which mandate glazing materials conform to certain standards. The mere fact that persons are constructing a vehicle for them selves does not place them above the law. I am not saying that polycarbonate is better that acrylic or that acrylic is better than polycarbonate, what i am saying is that if you use polycarbonate make sure it complies to relevant standards.

Personally I would use a complying material even if it is inferior to like products.

 

[Dave P]

Trevor:

Thanks for the answer. I appreciate your input.

 

[Neal]

TAP Plastics

 

[Grady]

I was at the Auto Fair here in Charlotte again this weekend. I have seen another GT40 with really crappy looking side windows. They seem to get very dull or crazed looking. I cannot remember seeing the lexan widows in our late model stock cars looking like that.
Is it choice of materials? Hot southern sun?

Hey Dave,
Was it my 'real crappy' side window you were looking at? It was the red MKII with the 427 FE. While the side window material in not as clear as the front glass or the 3/8" thick rear glass, it isn't doesn't impair seeing outside. Next to the clear front glass it is different. I think maybe micro scratches and UV works on the material. Something new would look better. A winter project.

I had to slap some hands (verbally) as 'the Guys' were trying to open the window vents by prying them from the outside with their finger tips. Twisting and trying to open anything they think will open. I had the rear opened up for several hours. The usual questions were ask.
"What is it? " "Is that a real 427 FE?" "How long did it take for me to put it together?" "What are these (Monza fuel covers)?" "Why is the steering wheel off?" "What are the wires on the spinner for?" Oh my favorite, "What kind of gas mileage do you get?". I need to get a placard made I guess.

Next time your there, ask where the owner is....I'm usually within sight distance of the car.

Ps- I found a door seal that 'seals' the doors while there. It uses a 5/8" bulb extrusion. I'll post somewhere in the DIY section as soon as I find a spot there.

 

[Dave P]

Were was your car displayed? The one I saw last spring was in the Roush booth.

 

[Grady]

Were was your car displayed? The one I saw last spring was in the Roush booth.

I was there at the Superformance/Roush stand on Saturday where they always are setup. I didn't have the car (40) there last spring, maybe I took the Cobra. Don't remember. I'd like to bring one of my Shelbys, but Roush is there with their family of engines in the Spring. Todd Andrews (ROUSH) and his band has helped me get a car ' I didn't intend to buy' back to Asheville. And I am there as a guest of Superformance.
Steve Saleen is going to be here on the 25-27 of this month for our Mustang get together (PONY Run). I've been wax on, wax off on the SGT/SC so it will probably go in it.

Anyway, I didn't see other GT40s there except for mine and the GULF car. Loads of lookers and a few that think they need to get inside or lift a latched cover. I don't have that much problem with the Cobra. Only the side pipes.:furious:

 

[Jim Cowden]

YouTube - Polycarbonate vs Acrylic Plastic

Jim