Plastic windows

[jhelgesen]

Who has made their own plastic windows for their 911?

Got an details on the seals to use?

TIA

[ZOA NOM]

I'm about to do this for my race car rear window. You can look at GT Racing's pre-cut windows and frame. I'm going to attempt to find a place that can bake a piece of lexan over the stock glass to form it, and use a factory seal. I tried to use a flat piece, thinking the compound curve wasn't severe enough to matter, but it cracked trying to install the seal. I think I might even try using a couple of heat lamps and just let the lexan slowly melt onto the glass.

[jhelgesen]

To shape the rear window, you can cut it close to shape, then clamp it to the old glass. Now the fun part, heat it to about 200 degrees and let it cool down slowly. As hot as it is outside, I thought of making a quick plywood box and painting it black, then put it in the sun. Some forced heat from a small heater would work to. You just need to heat the plastic enough to relive the stress of being clamped, then it will hold the shape after it cools. No need to make it melt. I used to form landing gear for rc planes in the oven this way.

[Formerly Steve Wilkinson]

I used Lexan for my rear window, in the stock seal, but for the rear side windows I use ordinary hardware-store Plexiglas, also in the stock seals. Using Lexan there is a waste of money, since they're not subject to any stress or potential impact. Windshield, I also have Lexan...though I'm damned if I can successfully fit it, using either the 911 or 964 seal, both of which I have. Gonna work on it some more next winter.

[Mahler9th]

There are several threads on this here on Pelican and you may find a search helpful.

I made some rear quarter windows out of cast acrylic (plexiglass), then decided that polycarbonate (lexan) is better so I am just finishing those. My approach for these is a frameless structure, and I attached little brackets to the car so that the windows can easily be removed. I will post some pics tonight.

My car came with 911 pop-out windows (black trim), which had polycarbonate inserts. I am going to sell these if anyone wants them.

In the rear, my car has a polycarbonate window and uses what I think is a 993 rubber seal. I think the window came from GT Racing. The only advantage of a flush mounted window (like the Spektr) is a slight weight savings-- their frame versus the rubber seal. The rubber seal weighs about 2-3pounds. So my guess is a pound or two of weight savings at best is what is achievable. But it is high weight...

The Spektr set up is ~$600 so it is not worth it for me right now. There is no measurable aero advantage of the Spektr.

I have a spare polycarb window with all of the righ"Spektr type" bends which I may use for a mold to make a flush rear window sometime in the future. I figure I can sell my set up and buy a piece of polycarb, form it, and make my own frame out of cf. So I can get rid of the 2-3 pound seal for mostly sweat equity. We'll see.

[Mahler9th]

By the way, acrylic quarter windows can crack at the holes. Mine did and that is why I made new ones out of polycarb. The cost difference is about $10-15 for the pair.

[RWebb]

a tidbit on this -- the new plastic windows have a much improved scratch resistant coating on them now.

IIRC, Corvette is using this on _street_ cars this year.

Dunno which manfs./models have this.

[ZOA NOM]

Mike,

I've been waiting since April for a window setup from Spektr. Finally gave up and asked for refund. He says his mold is bad. Not very good customer service at all. Had to hound him incessantly. He charged the credit card quickly, tho. I'll be trying DIY first, then maybe the GT Racing kit.

[Tim Hancock]

FWIW guys, regular lexan (polycarbonate) scratches very easily (multiple washings will leave fine scratches). It does not break like plexiglass (acrylic) does, but I am assuming you guys are replacing these "rear" windows simply for weight savings, not safety. Plexiglass is cheaper, easier to find locally, thermoforms readily and above all, is more scratch resistant.

I have built aircraft windshields/canopies out of both plexiglass and lexan and the plexiglass ones still look new while the lexan ones have very fine scratching even though I am VERY careful in when I clean them.

Lexan IS available with a "scratch resistant" coating, but it is even more expensive than bare lexan. Why bother with the lexan for rear windows?

[911pcars]

Sometimes, there is confusion between the two terms. For general info, here are the differences between plexiglass and polycarbonate:

http://64.233.167.104/search?q=cache:x8r-ZQgaLW0J:www.pecora.com/downloads/mastercaulk/The_Master_Caulksmith-Lexan_and_Plexiglass.pdf+plexiglass+vs+polycarbona te&hl=en&ct=clnk&cd=2&gl=us

There are various manufacturers of each. Lexan is a tradename for their line of polycarbonate. Lucite, Makrolon are others.

Sherwood

[RWebb]

"Why bother with the lexan for rear windows?"

b/c there is still the street car holy grail of a light, but usable rear window...

[Tim Hancock]

Originally Posted by RWebb

"Why bother with the lexan for rear windows?"

b/c there is still the street car holy grail of a light, but usable rear window...

In case that was directed towards me....I fully understand the desire for a light rear window, I just don't know why everyone wants to use Lexan (polycarbonate plastic) vs cheaper and more scratch resistant plexiglass (acrylic plastic).
No big deal, It is not my money and to each their own ultimately

[RWebb]

Lack of education?

[Mahler9th]

Polycarbonate is appropriate for a race car rear window, acrylic is not.

[Tim Hancock]

Originally Posted by Mahler9th

Polycarbonate is appropriate for a race car rear window, acrylic is not.

So the rules specify: NO plexiglass in rear windows? If so, then I am sorry for suggesting the cheaper scratch resistant plexi for those who intend to participate in sanctioned racing.