Forums » Grassroots Motorsports » DIY polycarbonate (Lexan) windshield
  • NBS2005

    Oct. 14, 2009 10:55 p.m. NBS2005 Dork

    Anyone make one of these? My RX-7 (I love saying that!) has cracked front glass so I thought about trying to fab something up that is $2010 budget friendly (yes, I've got $510 to play with, see you next year!). Has anyone made one? I was thinking of making it with 2 sheets with a frame of some sort that would help keep it from buckling. Sorta like this:

    http://www.theautoist.com/grmwindow06.JPG

    Though I realize that is one piece.

    Any thoughts?

  • Keith

    Oct. 14, 2009 11:18 p.m. Keith SuperDork

    Oooo oooo oooh! I've done it. It's easy.

    • make template out of paper
    • trace template on Lexan
    • cut lexan
    • drill holes
    • rivet

    It couldn't be easier. There's enough flex in the Lexan to conform to the bends in a Miata windshield without any sort of heat or forming. We used 1/4" in the front and it doesn't buckle at all, even at 140 mph. If you go lighter, such as 1/8" (as I've used for rear windows), you'll want something to support it.

    http://targamiata.com/tags.php?tag=lexan%20window

    The hard part is going to be keeping the price down to a Challenge-friendly level. Don't be tempted by acrylic (plexiglas), stick with polycarbonate.

    Square left in 50 caution ocean!

  • RossD

    Oct. 15, 2009 7:16 a.m. RossD HalfDork

    I've heard the trick to make it look professional, like Keiths, is to remember to paint the inside perimeter black.

    Calling all cars!

  • mad_machine

    Oct. 15, 2009 8:48 a.m. mad_machine SuperDork

    honestly, I probably would have thought of the perimeter thing.. AFTER I installed it

    German, Italian, Swedish, Collecting Europe one car at a time

  • Kendall_Jones

    Oct. 15, 2009 8:54 a.m. Kendall_Jones Reader

    Before the COT thing, there used to be a vendor of used Nascar lexan windscreens (also sold wrinkled fenders / hoods / etc). Sold them for like $20. I still have a couple for my road race projects.

    Kendall

  • Wally

    Oct. 15, 2009 9:03 a.m. Wally SuperDork

    The only thing I would add to Keith's instructions is pick up a roll of self adhesive foam insulation from Home Depot and put down a layer on the windshild flange to cushion the windshield to keep it from squeeking and cracking. Once the windshield is mounted you can run a bead of cheap black silicone around the gap between the windshield and the body and smooth it out with a wet finger to make a neater looking seal.

    .

    Drunken sailors spend cash that they've already earned. If our politicians started spending like drunken sailors, it would be a big improvement.

  • NBS2005

    Oct. 15, 2009 9:11 a.m. NBS2005 Dork

    Keith,

    That does look pretty easy! I love easy. Can some kind RX owner go out and measure their windshield for me? I'll wait.............(my car is not here yet, going to be a few weeks before I can go get her).

    I found this place on line:

    http://www.professionalplastics.com/POLYCARBONATESHEET

    Kieth's 24x 60 sheet would be $100 for 0.220 in thickness, $66 for 0.125 in. Cheaper than a windshield.

    Next up, bushings and what to do about the interior.

  • GameboyRMH

    Oct. 15, 2009 9:41 a.m. GameboyRMH SuperDork

    I've been thinking of doing some of mine to lose weight, and for safety (the rear quarters on the AE92 only have a slight curve, and all the glass on the Samurai is FLAT).

    How are these things with fog? Better or worse than glass? And what do you do to deal with the scratches, just clear plastic film?

  • Keith

    Oct. 15, 2009 9:46 a.m. Keith SuperDork

    There's probably a plastic dealer in your town, might be cheaper than shipping. I seem to recall my 0.125" sheet was right around $60 at a local shop.

    I've never had any of my Lexan windows squeak. If you use the right size holes for your rivets, they can't move.

    I don't live in a fog-prone area so I can't comment on that one. You do have to take care of them though. I haven't scratched one badly yet, but I would not recommend windshield wipers on one.

    Square left in 50 caution ocean!

  • cxhb

    Oct. 15, 2009 10:58 a.m. cxhb Reader

    Wally wrote: The only thing I would add to Keith's instructions is pick up a roll of self adhesive foam insulation from Home Depot and put down a layer on the windshild flange to cushion the windshield to keep it from squeeking and cracking. Once the windshield is mounted you can run a bead of cheap black silicone around the gap between the windshield and the body and smooth it out with a wet finger to make a neater looking seal. .

    or even better, buy a roll of 3M Window weld. its much tackier and is oem for some manufacturers. plus its black.

  • amg_rx7

    Oct. 15, 2009 11:08 a.m. amg_rx7 Reader

    Can't you just get one from a junk yard, ebay or off a parts car?

  • John Brown

    Oct. 15, 2009 11:11 a.m. John Brown SuperDork

    amg_rx7 wrote: Can't you just get one from a junk yard, ebay or off a parts car?

    Where is the fun in that?

    Internationally known as The Brown Stig

  • poopshovel

    Oct. 15, 2009 1:02 p.m. poopshovel SuperDork

    1/8" is fine. 1/16" is too flimsy. BEST way to cut is on a band-saw...actually, best way to do it is have your brother who builds furniture and knows WTF he's doing cut it on a band-saw.

    Rivets in the channel are perfect, and definitely spray an inch or two around the perimeter black. Bonus points for curved corners. On the civic, I had a strip of 3/4" wide, 1/8" thick aluminum stock running vertically in the center that helped to keep it from wobbling. That E36 M3 gets LOUD otherwise. And yeah, the foam tape is a great idea.

    Aye, que pena.

  • Wonkothesane

    Oct. 15, 2009 1:29 p.m. Wonkothesane New Reader

    About protecting it:

    I remember seeing at PRI last year that there's a few companies selling the equivalent of 3M's clear bra for window protectors... You should be able to get a roll of it for under $30, the way Nascar and other racers protect their lexan windshields :) Just put a few layers on and rip 'em off if it gets scratched up.

  • NBS2005

    Oct. 15, 2009 2:28 p.m. NBS2005 Dork

    I've never priced used windshields before. What do they run?

    I like the durability factor and lower weight of the lexan.

    Does Rain X work on plastic?

  • poopshovel

    Oct. 15, 2009 2:53 p.m. poopshovel SuperDork

    Does Rain X work on plastic?

    Yes. You can also buy polish/scratch remover from lexan suppliers like piedmont plastics. DO be super careful using anything else on there, though. We made an entire hatch out of lexan for our $2004 challenger. The morning we were supposed to leave, I noticed a tiny bit of somethingeruther right in the middle of the thing. I grabbed a can of goof-off and applied it liberally. I was up till 3 in the morning building a replacement hatch.

    Aye, que pena.

  • RossD

    Oct. 15, 2009 3:03 p.m. RossD HalfDork

    When I replaced my cherokee's windshield, I called around to the local shops and then called a national chain. The national chain was only like 50cents cheaper and so I was going to go with a local shop and I told that to the lady on the phone. She instantly dropped the price by $50. I think I paid just over $200 and the guy came to my house after I was done working and we talked cars the whole time while he swapped out the windshields.

    Calling all cars!

  • daytonaer

    Oct. 15, 2009 3:03 p.m. daytonaer Reader

    NBS2005 wrote: Does Rain X work on plastic?

    RainX anti-fog will melt some plastics. Be careful.

  • Karl La Follette

    Oct. 15, 2009 3:47 p.m. Karl La Follette Reader

    Use a vinyl banner for top of windshield and tearoff www.racetearoffs.com

  • patgizz

    Oct. 15, 2009 4:31 p.m. patgizz Dork

    the home depot has real lexan now - not sheets large enough for the typical car windshield, but for my truck where it is 2 small halves.... cheap source of windshield for me

    John Brown wrote:"Safety" is my second middle name, it's right after "Screw".

  • Oct. 15, 2009 7:01 p.m. redzcstandardhatch New Reader

    on gutty, we had some CRAPPY plexi and lexan in the rear windows (took it out of storm doors that we replaced)

    it was scuffed, etc.

    TURTLE WAX YO

    we waxed it all a couple times , and it looks PERFECT. just a note for future care..

  • poopshovel

    Oct. 16, 2009 8:43 a.m. poopshovel SuperDork

    patgizz wrote: the home depot has real lexan now - not sheets large enough for the typical car windshield, but for my truck where it is 2 small halves.... cheap source of windshield for me

    Home Depot is WAAAAAAY overpriced compared to plastics suppliers like piedmont.

    Aye, que pena.

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