lexan windows [Merged 4-7] polycarbonate

[almostquick]

and as far as thickness goes as far as I understand the thickness is only mandatory for the windshield (which requires 3/16 minimum thickness) but all the other windows can be whatever you prefer. I'd also have to disagree with the weight comment, I'm willing to bet you can save a substantial amount of weight going with lexan for the front, but also remember if you do the front your probably going to want to put in 2 support bars to keep the lexan from bowing in.

 

[15psi88]

Almostquick, I noticed that you riveted in your hatch. Is that a must? Why couldn't you install it like a real window. Reason I ask is because my car isn't an all out race car. It might see some street duty, I don't want the police eye to notice that I've got lexan windows. I'm not sure that it's illegal or not, but I've got enough things to worry about. I only plan on doing the rear three also. Where did you guys get your sheets,and what did you use. I'm planning on using 0.25" in whatever I decide. I'm just a little worried that polycarbonate will scratch way too easy. Are their different grades,or types that have better abrasion resistance?

 

[almostquick]

race car...this aint no race car, I drive mine on the street as well. But to answer your question, yes your going to need to rivet them in, if you find a better way please let me know. Look at the curvatures of the windows, theres no way your going to get something flat to curve around an object with just silicone like the factory glass is. Doing the back three is very hard, as you can tell I havent taken that task up (besides the hatch).....because it will look like complete shit, I havent seen a set of b-pillar windows that has ended up looking decent yet, you will need to rivet roughly ever 1-2 inches and even then it will bow inbetween, yes lexan is extremly flexable but even at those angles its going to fight very hard to go back to its natural state. now you want to be sneaky so the fuzz wont notice your sporting lexan windows, I would then do smaller (special order anadized black rivet heads online) rivets as close to the edge as possible and then make sure you are able to salvage your stock weather trim around the glass and put it all back on. But there is an alternative you can cough up the dough and by the premolded stuff that is made just for our cars (flex-a-lite makes it). Now for supplies, if you've done your reading you know the normal lexan is wonderfully light, very bendable, and oh ya...it will scratch easily and yellow once in the sunlight for enough. I bought most of mine through Homedepot, Its lx10 if I remember correctly, so it has all of those characteristics but it has been UV treated so it will not yellow. However if you look online you can get many different flavors...the normal stuff, the stuff I used (lx10), lexan that is uv and scratch resistant (I think it is called mr10), and even tinted lexan if thats your fancy. but the latter two will most likely need to be special order and ofcoarse it is going to cost more. Now that I have wrote a nice long journal.......Go and bust out your windows, or if your a pro remove them the right way and get to work making your cardboard templates and cutting up some nice lexan.

 

[99gst_racer]

and as far as thickness goes as far as I understand the thickness is only mandatory for the windshield (which requires 3/16 minimum thickness) but all the other windows can be whatever you prefer.

Per NHRA rules:

7:8 WINDSHIELD, WINDOWS
Windshields and/or windows on all cars must be of safety glass,
Plexiglas, Lexan, or other shatterproof material, minimum 1/8-inch
thick, per Class Requirements. In Championship, Heads-up
classes, windshields and/or windows must be clear, without tinting
or coloring, except factory-tinted safety glass. In all other
applications, windshield/window tint must meet applicable state
requirements. Competition-number decals are permitted on any
window, windshield, or backlite, except as noted in Class
Requirements.
Tape of any kind prohibited on any windshield or window.

I'd also have to disagree with the weight comment, I'm willing to bet you can save a substantial amount of weight going with lexan for the front, but also remember if you do the front your probably going to want to put in 2 support bars to keep the lexan from bowing in.

Exactly. One large piece of .125" thick polycarbonate sheeting, plus the weight of metallic supports. Depending how you attach the the windshield (ie: steel screws, or aluminum rivets), and type and quantity of material for bracing, it could easily build-up to be just slightly lighter than the OE windshield. The OE one weighs 27-30 lbs. I've heard of other aftermarket windshields being a tad over 20 lbs.

I'm planning on using 0.25" in whatever I decide. I'm just a little worried that polycarbonate will scratch way too easy. Are their different grades,or types that have better abrasion resistance?

1/4" polycarbonate is thick as all hell. You aren't going to save any weight going to a material that thick.

This is the stuff that I am using on my 1G. It's not quite .125", but it's damn close. It's also available in a scratch-proof version, but is more money. They also have a special cleaner to use with these polycarbonate sheets - Cleaner.

 

[15psi88]

almostquick,
Isn't there a way to mold the lexan to the stock shape, with a heatgun, or maybe in the oven? If you were to clamp the lexan to the stock glass that is.

Thanks for giving me a heads up 99gst_racer.
I guess 0.25 is a bit thick, I could do .125, but would it fit into stock location without rivets?(granted that I can mold them myself) Does anyone know the stock thickness of the glass?

 

[99gst_racer]

Does anyone know the stock thickness of the glass?

I'll find that out later today. I have all of my glass pulled right now, so I'll throw a mic on it and report back.

 

[almostquick]

almostquick,
Isn't there a way to mold the lexan to the stock shape, with a heatgun, or maybe in the oven? If you were to clamp the lexan to the stock glass that is.

Thanks for giving me a heads up 99gst_racer.
I guess 0.25 is a bit thick, I could do .125, but would it fit into stock location without rivets?(granted that I can mold them myself) Does anyone know the stock thickness of the glass?

I've never seen it done nor have I heard about people molding the lexan with a heat gun.

 

[15psi88]

Alright thanks guys, I'm going to see what I can do on my own. I will start my own thread when I'm done. Maybe even write a tech article if all goes well.

 

[99gst_racer]

Glass thicknesses:

Rear, small side windows: .135"
Hatch glass: .141"

I can't measure the windshield as I will not be removing that one. And I couldn't get measurements on the door glass because my doors are buried somewhere else in the garage right now.

 

[DirtyBirdRacing]

Subscribed.

Bill

 

[15psi88]

Glass thicknesses:

Rear, small side windows: .135"
Hatch glass: .141"

Thanks a lot. I'm going to hit up Lowe's in the AM so hopefully they can do something for me. Maybe tomorrow I will have some more information.

 

[silver bullit]

Does anyone got stock glass weights ?

 

[99gst_racer]

Does anyone got stock glass weights ?

Bucci claimed the windshield he pulled from his Laser weighted in at 30 lbs. I have my other glass pulled right now, but I don't have a weight scale... Hopefully someone else can chime in as I am very interested to know numbers as well.

 

[15psi88]

Hey guys, I got the stock triangle windows out today. Started making the new ones from some Lexan I got at Lowe's. I just weighed those windows ,on a bathroom scale, and they weigh about 3.5lbs. I weighed my Lexan and it weighs just over 1.0 lb. To let you guys know I will never attempt this again after I complete this set. For a 5.0Lb weight drop and a $60.00 total It's really not worth the time or money to me. I will be looking forward to the hatch glass though. I hope there is some serious weight to be made up there. If anyone knows, or can get it before I take mine out please let me know, I want to make sure it's worth it.

I got a window roughly cut out. Tomorrow I'm going to clamp it up and pour some boiling water on top in hopes of molding it. I will let you all know how that goes.

Oh and by the way, the sealer the factory uses is a pita to clean up, and there is a ton of it.

 

[99gst_racer]

Yeah, those side windows are light as hell, but the hatch glass is definitely heavy. It will be worth it to replace that one. Have fun removing it too - it was a complete PITA. Let us know how much it weighs.

 

[SBstar]

Stock hatch glass weighs in at about 25-30lbs. Using a bathroom scale I'm giving a 5lb. margin for error I think the best windows to save weight on are the two sides and the rear, those little guys aren't worth the trouble and the who wants to deal with the front, plus what Paul said about the weight thing anyways.

 

[unlmtdndeavor]

HiRev Performance was selling lexan rear hatches in their CF Hood & Hatch thread.

 

[InfiniteGSX]

Yeah, the rear window sucks! I replaced mine... I just took the hatch off the car and replaced it that way... its atleast half the weight of the entire hatch.

 

[bpestilence]

People keep saying that Speedglass is not Lexan. It is. It is simply coated to make the Polycarbonate scatch resistant. You can do the same thing by simply applying tint to both sides of the Lexan after you are done cutting and shaping them.

I have done Lexan windows, not for a car, but for the SAE team at my alma mater. It is really not as hard as you might think. Firstly, you need Lexan (or no-name PC in a similar thickness to the OEM glass). A standard-sized sheet is enough for at least the rear and quarter windows.

Next, you need a form. The OEM glass works perfect. Either get another hatch to work with, or be willing to be sans car for the time it takes to do the work. Remove the window glass, clean the crap out of it and make sure to polish out any sand pits, etc.

Next you need to apply heat. For small parts you can use an oven, but unless you have a kiln or a pizza oven lying around, you are SOL for the hatch glass. What we did in SAE was to use IR lamps. The same sort of thing you use to cure powdercoating, or to keep your snake happy in the winter. Having an IR thermometer is also handy.

The important part is temperature control. Here is a good article:

http://www.thermoforming.com/Articles/IAPD-Polycarbonate/Thermoforming.pdf

Anyway, 350-370 degrees is what you need to get to to make it thermoform, but if you get above 450 degrees you will cause bubbles to form in the material. This is why heat guns are so difficult to use to form the material.

You have to heat up the part slowly, and cool it slowly. Keep the area clean because the plastic will absorb any dust or grit that it comes in contact with.

Now that it is formed, cut it to the same size as the OEM glass, and tint it. You can get tint with as much as 95% VE, which will give the part an overall 75% VE when finished. (.125" PC has about 85% VE to start with) Reinstall the "glass" using the same butyl strips that the OEM glass was held in with.

Now, as long as you don't live in Egypt or Death Valley, the window should never sag. The compound curve will tend to keep it in shape.

I will post pictures when I actually attempt to do this technique myself on my car.

 

[compression]

there is one downfall to lexan is, and its that most import drag racing events prohibit lexan windows in the street tuner classes which in most cases is what you'll be running in.
i was dead set on getting a fiberglass hatch and lexan rear window but i found that they prohibit it in the regulations.

 

[InfiniteGSX]

If you tell them! Its not illegal unless you get caught. I'd install the lexan to look exactly OEM.

 

[10_seconds_2luv]

there is one downfall to lexan is, and its that most import drag racing events prohibit lexan windows in the street tuner classes which in most cases is what you'll be running in.
i was dead set on getting a fiberglass hatch and lexan rear window but i found that they prohibit it in the regulations.

What about the preformed Flex-a-lite Poly rear hatch window.........would that be illegle also?

 

[99gst_racer]

What about the preformed Flex-a-lite Poly rear hatch window.........would that be illegle also?

Yes. For a racing class that requires the car to be "street legal" in some aspects, even the Flex-a-lite polycarbonate windows would be illegal. One of my co-workers won the FAL Acura RSX at this year's SEMA, and they had to replace their own windows with the factory ones before they let him take delivery.

 

[bpestilence]

Yeah... Even with proper forming and installation, they will still be able to tell it is not OEM glass. The OEM glass has the "dot matrix" tinting on it, and the defroster grid. Unless you cold mimic that finish, there would be no way to stealth a Lexan window past the inspectors.

 

[compression]

Yeah... Even with proper forming and installation, they will still be able to tell it is not OEM glass. The OEM glass has the "dot matrix" tinting on it, and the defroster grid. Unless you cold mimic that finish, there would be no way to stealth a Lexan window past the inspectors.

especially not one of the largest windows on the vehicle although i wish they would lighten up a little bit on the rules ( ha ha i made a funny )