polycarbonate sheet windshields

[Belatti]

I have a problem with the polycarbonate sheets I use as windshield in a sport car. When you look through it you see everything "curvy" ... more or less like what you see when you look through hot air. And facing the sun the curved polycarbonate decomposes light into a faded rainbow.

Glass is out of the question... the geometry is too complex to use it (and glass is heavy).

Acrylic plastic is dangerous, it can turn to splinters in a crash.

Can you give some advice on what to do, what to buy (even if its another kind of sheet) or even how to install the sheet to improve this?Do you recomend me to use a polarized sheet?

[Nortad]

acrylic might be a solution if you laminate it with some sort of film.

I have a catalog around here somewhere of such a product (used as anti-theft protection in door windows on normal road cars) that might do the trick, Im gonna look for it.

cheers

[terence]

Lexan is a good choice,its also available with a 'scratch proof'surface.It is also very easily 'worked'.

[XKRacer]

I have used Makrolon in the past but I think this might cause the same issues you already have and pretty much the same stuff everyone has mentioned.

Have you spoken to http://www.plastics4performance.com/ they are doing all my plastic screens for me at a good price for a 'not off the shelf product'.

[HighLine Polycarbonate]

Polycarbonate is the best material for the application and is used by NASCAR. My company is a producer of Polycarbonate sheet and the following information comes from a number of years supplying into this market.

The problem is probably the choice of Polycarbonate. Material sold at DIY stores is the general purpose grade of Polycarbonate under trade names such as Lexan or Makrolon. The optical properties of this material is not the same as some of the optical grades sold for higher end applications. This material can have a lot of distortion, which appears as waves in the material.
These waves can cause the rainbow effect and distortion.

Another cause of the rainbow effect is the hard coating that is sometimes applied to stop the material scratching. If this coating has not been applied correctly the rainbow effect occurs. This effect is far more noticeable under fluorescent lights and is not usually an issue outside.

To solve the problem, you need to get the right Polycarbonate. Unfortunately we sell only to major users of Polycarbonate (if you need a pallet of 100 sheets or more, we could supply, but I am guessing that you don't need that much!).
Probably the best place for quality windows is Five Star Race Car Bodies. I don't know if they supply direct to users, but they certainly have distributors - so a search of google should find something. Their windows also have a hard-coat which protects against some scratches. I am sure that there are other quality producers out there as well.
The problem is that quality windows from Polycarbonate are likely to cost you more than the general purpose stuff from DIY stores.

[terence]

Lexan available from DIY stores?

[GORDON STREETER]

I have always used Lexan brought from my local glass works. Fortunately my screen has no major curves so impaired vision isn't a problem and is very easy to make with a jigsaw.
However wipers do scratch the surface and that can be a bit of a problem when the sun is low in the sky. Compared to a laminated screen they are a fair bit cheaper and don't break, I put a new one in every year.

[Al Weyman]

Lexan is polycarbonate I believe and surely just a trade name. I doubt you would buy it thick enough from a DiY store would you? Go to a sign shop or a trade supplier like Vulcascott or Amari and see if they can do you a half sheet or offcut.

[Belatti]

Thank you all guys!

Now I know its not the material type but more about the material quality or grade. Ill see what I can get down here and then I´ll feed back the thread!

[phoenix]

I know you are not in the UK - but I use:

http://acwmotorsportplastics.co.uk/default.aspx

[bdwoody]

i thought that maguard was the stuff to use as it was tougher than lexan ... i may be wrong thou .

[HighLine Polycarbonate]

For information on the producers and types of Polycarbonate:

1) SABIC (Saudi Arabian owned) - used to be GE plastics

Trade names

Lexan - standard Polycarbonate sheet
Lexan Marguard - abrasion resistant coated Polycarbonate sheet.

These grades can be picked up from a wide range of plastics distributors. A good distributor will help you get one of the higher quality Lexan sheets.

2) BAYER (Sheffield Plastics in the USA)

Trade names
Makrolon - standard Polycarbonate sheet
Makrolon Hygard - abrasion resistant coated Polycarbonate sheet.

These grades can be picked up from a wide range of plastics distributors. A good distributor will help you get one of the higher quality Makrolon sheets.

3) HighLine Polycarbonate LLC

Produce a grade for race cars with a formable abrasion resistant coated Polycarbonate sheet. At this time it is only sold to companies specializing in NASCAR and racing windshields in the US.

Using a sheet with an abrasion resistant coating will help reduce the damage from windscreen wipers. However, it still will eventually scratch as Polycarbonate is not as resistant to scratch damage as glass.

Hope this helps.

[GORDON STREETER]

Originally Posted by bdwoody

i thought that maguard was the stuff to use as it was tougher than lexan ... i may be wrong thou .

Have you ever tried to break lexan ?

[terence]

Yes,quite Gordon,amaizing that it can be folded into a ninety degree.

[GORDON STREETER]

Many years back when I first started to use Lexan windscreens I was told by a scrute that plastic screens were dangerous as they splinter and cause injuries and he refused to pass my car. I explained that it was unbreakable and said if you can break this screen with this 2 pound hammer I will willingly go home.
He took me up on this, so I told him to clout it as hard as he could on the passenger side as it would probably mark it.
I had to look away as I nearly p***ed myself as the hammer bounced off the screen and clipped him in the ear !.
Although looking back it could have really caused a serious injury.

[Nero]

One issue is its potential over use. Having watched marshals try to extract a driver from a car with all poly windows that was upside down and in danger of catching alight, I might suggest that the side windows either need to be of a different material or be scored so that they can be broken easily if required.

[GORDON STREETER]

Good point Nero, but you can lever them out in a hurry just like a laminated screen and they won't cut you. Also they don't leave debris on the track.
But that's up to the "powers that be" to decide

[R59]

I use Makralon Hygard, it's not that cheap, though it was for a 4m x 3m sheet, and I made a front and rear screen for my Pontiac GrandPrix ASCAR, and have enough left to do a screen for my Belmont, and maybe one more. I seem to recall that the sheet cost about £400ish, which I got from Amari Plastics (they have branches all over the UK).

[Al Weyman]

Should have spoke to me Rob ;-)

[Timmyevo6]

would anyone be able to tell me if its possible to make a screen for a evo 4-5-6? and if so, how? also where to get the stuff from and what spec does it have to be to conform to MSA?

[GORDON STREETER]

Originally Posted by Timmyevo6

would anyone be able to tell me if its possible to make a screen for a evo 4-5-6? and if so, how? also where to get the stuff from and what spec does it have to be to conform to MSA?

Yes its perfectly possible to make a screen for an EVO.
Go to you're local glass supplier and buy a sheet of Lexan polycarbonate.
Leave the plastic protective coat on the Lexan, and using a screen as a pattern drawer round it with marker pen and simply jig saw it out.
If the original screen is too curved to hold the Lexan to it you may have to make a pattern with cardboard first.
However I don't know about bonding it in as I just use self tappers.
It depends what you intend to use the car for as although polycarbonate is light compared to laminated glass and (can be cheaper) the vision will deteriorate over time with scratches from wipers and cleaning, and doesn't make a good road screen !