Why did I become obsessed with plastic windows? The latent racerboy within? Anyway after 5 years of surfing and some amateur application I feel somewhat able to offer tips based on lexan rear Fiero window and (crowning achievement or folly) plex hatch window ,NX2000. (Diehard buy America fans must forgive, it's my other test mule). The stuff is light and strong (esp lexan),but does have limitations. Why don't carmakers offer the lighter stuff? Lexan won't break so you can be extracted (perish thought). Plex won't shatter like safety glass. Both scratch. One major issue : Steel and glass coeffs of expansion are close so they can be bonded tightly together and are rainproof. The plastics are very unruly and will not be locked in place without cracking.
I have read many sad stories from boat guys who try to achieve that water tight seal and wake up to nasty cracks. Only a few adhesives work with these two plastics I found one which is architechtural in origin. If any of this blather is of interest I will say more. This is not to tease or build thread count, only because I tend to rave on.

Good info.

Can lexan be used for a window in the rear deck lid?

Driver, Sorry I just reread your inquiry of "decklid". Off the top it reminds me of an Italian exotic who used it (was is Lamborghini?) The stuff is flammable and is attacked by various vapors and chemicals. I don't know what you have in mind-a show window or a larger area? If it's a large area it would probably be thick and might have to be formed (expensive)

For the rear window it's a slam dunk on the Fiero , being flat. Mine is smoked .093" . Weight 1-1/2 lbs vs glass @ 12 lbs. Only drawbacks: removal of Fiero glass and the width prohibits Lowe's purchase. There is at least one thread on glass removal, and several have the lexan. I used a narrow putty knife and a small plastic mallet inside. Once you have driven through the adhesive add a soft wooden wedge. Continue gently around with the wood wedges (cut 'em on a bandsaw). Finally go the braided cable route with two handles, and add thicker wedges. The adhesive is amazingly rebonding and very frustrating. This is a PITA as noted. Patience. I took several days off and on ambient 40F. Heat does not help. I did remove the engine lid.

My window is held in with aluminum clips with fabric buffers, no adhesive. No leaks after 2 years. The lexan is twice the money. I would use plex (acrylic) clear next time. Ask if more detail is disired.

[This message has been edited by hobbywrench (edited 02-03-2013).]

Well on the Lamborghini Gallardo, several owners switched from glass to plexi, because the glass decklid shatters when one washes a hot car and the cold water hits it.

http://www.lambopower.com/f....php?showtopic=17156

Lambo Gallardo, shattered decklid glass fix

Cracked decklid glass:


Finished poly carbonate decklid mod:

Austrian, beautiful stuff. If I read it right one is tempered glass, the other lexan. One had difficulty with curvature which would have required a mold unless very thin. I have put quarter widows in with thin material under slight tension (only plex-lexan is too stiff) NX2000. Molding done right requires male/female molds and 350F for hours,then annealing. I choked on a local bid of $650 for a rear window. There is also "drape forming" with only one form. The problem is oven size availability. You will read about cold forming lexan and heat gunning but these do not seem satisfactory. The lid with the rubber seal is interesting. If it is plastic there must be about 1/4 " clearance all 'round the perimeter for expansion. It cannot be solid sealant. Therein is the problem of water ingress which may not affect that app so much.

Thanks for posting this info. I find it particularly useful, since I plan to replace the Fiero's rear window with lexan or plexi.

You mentioned thermal expansion / contraction as an issue. I guess that's why race cars use metal tabs to hold the windows in place, instead of the usual window mounting methods.

quote Originally posted by Blacktree: Thanks for posting this info. I find it particularly useful, since I plan to replace the Fiero's rear window with lexan or plexi. You mentioned thermal expansion / contraction as an issue. I guess that's why race cars use metal tabs to hold the windows in place, instead of the usual window mounting methods.

Blacktree, I always look closely at any NASCAR windows (don't follow it) and WRC windows(do follow it but it was dropped by speed channel and I'm considering suing). You will see button head type fasteners on the NASCAR back widows. I assume those are set in dry with "3 times" fastener dia holes for movement and they do not worry about water. The front NASCAR windshield look like lexan to me, and I cannot tell if they are molded or bent. Some have a vertical "stiffener" rod showing in the middle. Side WRC windows look like fasteners also and front side have flat ones (typically) with sliders or
nothing for vent. Also I just watched Dakar . Those cars seem to go flat whenever possible.

It is tempting to consider lightening the Fiero door windows,but they are curved and would require forming. Although coatings to reduce scratching are available , see more $$ and long run frustration.There are a number of vendors offering formed windows for American and Japanese (Honda) cars. None I have found for Fiero. I mentioned that despite all odds against I have a 48" x 54" clear plex hatch window in my Nissan NX. It has stood the summer/winter test and has not blown out at 90mph. Forming guidelines dictated 1/4" (based on architect chart of 100 mph wind), but I went under that (?3/16?). I cold bent Lowes clear plex and used Pecora (sp) adhesive with aluminum tabs (no through holes) . First draped fitting was disappointing, however as the clips were installed and the plex forced to follow the curvatures it stiffened and is fairly rigid (I did consider a stiffener rod a la NASCAR). Best analogy is pushing on a plex window in a convertible top. It has not yet undergone the 15 pound jumping tomcat test which is bound to happen.Weight savings 17 llbs. This was calculated to be more ,but Nissan had artfully produced a really thin hatch window which reduced the weight savings. I am channeling water outside the clips but do have leakage.

interested on ideas for side windows.... cost HAS to be less than glass.

quote Originally posted by jaredmurray88: interested on ideas for side windows.... cost HAS to be less than glass.

Jared, IMO plastic side windows in the Fiero would require heat forming unless you wanted to go real racer boy with sliding or small hinged flap openings. As I mentioned above making them is likely beyond the capabilities of the average enthusiast. You would use fairly thick material-plex in this case because you would want to be able to break your way out (perish thought). With lexan forget it. As a minimum you would take out your stock glass and attempt to "drape form" in a 300-350F oven- using the convex side of the window (where would you get an oven?- maybe an old pizza oven). I estimated a cobbled up home made @$200-$300. You need a heat source and a way to control to around 300F. A further annealing cycle should be done at a reduced temp. The drape forming is usually done over muslin or felt and cannot have any wrinkles. Many professionals would require two piece mold tooling which I mentioned was ball parked @ $650 locally for one back window. Add the price of the plex. Gets expensive fast. Of course the home enthusiast should expect one learning cycle or more. So if you mean HAS to be less expensive than custom glass - I don't know. This is the distilled knowledge of my amateur pursuit. I love plastic.

My Nascar T-Bird stock car had all Lexan windows with the windshield covered with several layers of Mylar 'tear offs'. It was held in by clips with bolts and nutplates in the sheet metal and also with 3M Super Yellow Weatherstrip Adhesive (flexible and sealed mostly for air blockage). If air leaks by, 150 mph wind can suck it right out.

I can get a kiln off a family member maybe... I origonally wanted the kiln for in my shop to powdercoat my own items after I get the garage up and running. The kiln is very close in terms of heat limits up to 600 degrees and roughly four feet by three feet square. If I laid it on its side a side window would easily fit inside of the kiln

In the past, Archie used plastic side windows.
And venders have been offering plastic quarter windows for some time. They must know the secret.

quote Originally posted by rogergarrison: My Nascar T-Bird stock car had all Lexan windows with the windshield covered with several layers of Mylar 'tear offs'. It was held in by clips with bolts and nutplates in the sheet metal and also with 3M Super Yellow Weatherstrip Adhesive (flexible and sealed mostly for air blockage). If air leaks by, 150 mph wind can suck it right out.

Roger , I hear you. On my NX rear window (unformed, clipped, bonded, ?180" thick , I held my breath during the first 90 mph test , worried about pop out. I have also tried "windows down" at 70 with no problem.
I imagine there is a slight bow out at speed on mine but have not seen any fellow motorists gawking or pointing. Architect charts (skylight technology) suggested thickness of .200" for my rear window to withstand 100mph winds. Formed .200" is what I wanted. Maybe I can visit Jared (post above) and knock one out after he becomes an expert.

[This message has been edited by hobbywrench (edited 02-06-2013).]

Sounds like we got a plan lol I was going to go with the draping method since it seems the easiest. If the family member gives me flack about the kiln I will be sure to keep my eye open for an old oven in excess of 36".

I really know nothing about how archie had his windows made, other than they werent glass, until recently.

After denying I watch NASCAR I admit I unavoidably scan it when looking for other sport coverage. So I guess the "new" rule NASCAR formula includes side windows so we can believe they are really stock cars...anyway

The cars apparently include plastic side window(?s). I got a good look at the passenger side today. They had buffeting problelms with the first (?) attempt. The latest looked like this: A channel up front , above and below, and a push type pinch clip above rear which locks the upper rear down to a fiber flange running around the perimeter (think jig type or woodworking hold down). In addition a NASA duct had been cut in the forward section for ventilation. The journalist got a demo from the pit dude. The window went in easily. It looked like clear plex, but cannot be sure. That's all for now from yer humble reporter.

any new findings on this topic?

No not on my end atleast I have been having construction delays due to weather being a crap shoot and my site is having drainage issues. I did however find a reasonable source for 1/4 lexan 5X10 sheets. I also had an idea to make up sunroof "glass" with a scoop like the fiberglass ones and can be tinted unless I can find cost effective pre tinted lexan too.
Edit to add: any Ideas on this? What would be better, facing foreward to make pressure in the cabin or backward to cause vacuum?

[This message has been edited by jaredmurray88 (edited 03-18-2013).]

Why would you want the Lexan tinted? Also, make sure it's UV proof grade, otherwise it'll age very quickly..
If scoop, I'd probably open it up towards the rear. (just based on Fiero aerodynamics videos, and the pattern most Supercar rear louvers are)

I just thought the sunroof would be best tinted already so the buyer wouldn't have to tint and if there was a demand for tinted side windows also. Marketability is mostly all thats behind the tinted lexan lol.

Nascar only uses the slide/clip in side window on Super Speedways like Talledaga and Daytona. All my Nascar windows were lexan. The side window may be plexiglass because its more rigid. Cant say for sure because we never had them in mine. They were having trouble keeping them from deforming and blowing out this year with the new Gen 6 car. They made a bunch of mods, like longer slots, and riveted metal braces on the insides. One of the downsides of plexiglass is the sun crazes it and makes it harder to see thru or even crack. They both scratch with windshield wipers, so you cant use either on a street car with wipers. Larger aircraft DO have wipers but Ill guess the windshields are composites of lexan and a glass outter layer. Military planes I flew had plexiglass canopies and no wiper...we used Rain X. The high speed air kept them drier than any wiper could. My MB SL has a lexan rear window in the hardtop. Its easily scratched. Its glued in all around all 4 sides. The conv top has the old style vinyl windows...also easily scratched.

Roger, Interesting... there are surface coatings advertized to reduce scratching, but no experience here, Please note my own observation on lexan. It is much , much stiffer than plex. How does a mfgr "glue" the perimeter? Perhaps adhesive. I searched a long time for the one I have on my Nissan with a proper "modulus." It allows 3/8" movement of the plastic thru winter-summer . So far no cracking or leakage. It was designed for architect (construction) use.