working with Lexan/replacing rear windshield

so I'm replacing the rear window for 2 reasons...


1) I had to remove the rear window to fix my rear chassis issues, so might as well get some weight improvements out of it, eh?

2) While removing my rear window, I accidentally shattered it....so now I NEED a new window anyways.


"Necessity is the mother of all rally upgrades."

so I'm probably going to go with 1/8" lexan....its a pretty big piece, but I've never worked with it before so my big question is, just how flexible is it?

Will I be able to just cut-to-fit and then glue it back in, bending it into place and it will stay there? Or do I need to brake out the heat gun and form this thing into a permanent curve? Also, how hard/easy is it to cut this stuff? For my UHMW stuff I just use a hand held jig saw and it cuts really easy and leaves a nice clean edge, will polycarbonate act the same?

Will glue last in the long run, or should I drill some holes and bolt this fucker down? Any tricks to drilling?

Or how about.....put a smooth layer of glue on the car, let it dry, and then bolt the window down on it tight so it seals, but its not actually glued to the car so I can easily remove it if I need to in the future?


I like the last idea...just though of it now.



a 24"x48"x1/8" piece is only $39 from this place:
http://www.iplasticsupply.com/shopping-cart/polycarbonate-makrolon-lexan-sheet/

so a custom piece slightly larger shouldn't be too much more. This is the same place I get my UHMW and I need to buy more so this is good timing for once.

I use stainless steel buttonhead screws to attach mine to the frame. Probably should have done some weather protection, but I just let the rain and snow in.
I didn't bother with a heat gun, but then again, it's a rally car and I don't care how it looks up really close.
Yeah, hand held jigsaw for mine. Painted a black frame on the inside for cosmetics.

Guess you didn't get a chance to weight your old window?

was your old window 1/8th" thick?

Ive always riveted mine but i guess you could glue it. You will want to paint the lexan where it hooks to the car. It will show any junk between the lexan and the mounting surface.

no, i didn't

it was a little bit thicker than 1/8th....but I see no reason to go to 3/16"

These guys have 5mm windows. 5mm is just a bit thicker than 3/16th. since its the rear window, I'm not worried about anything hitting it or whatever.

they also claim its half the weight:
http://www.plastics4performance.com/Lexan--Makrolon--Perspex-race-and-rally-windows-and-window-kits/SUBARU---Lexan--Makrolon-polycarbonate-windows/IMPREZA-GD/WINDSCREENS/SUBARU-IMPREZA-2-POLYCARBONATE-FRONT-SCREEN-SPRINT/p-288-489-493-663-475/

(and at 300 pounds, I'm saving quite a bit of change)



Edited 2 time(s). Last edit at 07/27/2011 04:15PM by Jon Burke.

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Jon Burke
no, i didn't

it was a little bit thicker than 1/8th....but I see no reason to go to 3/16"

well there's that damn rule book thingy, 10.2.5.e that says you can't go thinner than OE windows ..... i think for Nasa it's open though

But i think that's why you said you were about to order the 3/16th crap

Maybe there's a loop hole of sorts.. maybe you can use a window net back there.....
er no. (probably would be horrible dust wise)

the Spec C STI uses thinner rear glass, from the factory... trying to find the actual thickness in print.. i would think matching a factory subaru winddow for your body style would be A-OK ...



Edited 2 time(s). Last edit at 07/27/2011 04:29PM by A1337STI.

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A1337STI

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Jon Burke
no, i didn't

it was a little bit thicker than 1/8th....but I see no reason to go to 3/16"

well there's that damn rule book thingy, 10.2.5.e that says you can't go thinner than OE windows ..... i think for Nasa it's open though

But i think that's why you said you were about to order the 3/16th crap

Maybe there's a loop hole of sorts.. maybe you can use a window net back there.....

edited my post, I was looking at the wrong link. yeah, if the rules say so, then I'll get 3/16 I guess.

http://www.insideline.com/subaru/impreza-wrx-sti/2007/first-drive-2007-subaru-wrx-sti-spec-c-type-ra-r.html its a GD with the subaru "lightweight glass" ... can't find the thickness though

sorry my damn reading comprehension and retention is annoying at times...

You may want to measure the lexan to see how close it is to .125. I measured the rear glass it is .134 thats pretty darn close to 1/8". Do you think RA would not allow you to race over .010 on rear glass?



Edited 1 time(s). Last edit at 07/27/2011 05:23PM by Reamer.

Glue won't really do much. In my experience with a lexan windows (GTX hatch), the window expands/contracts quite a bit, so eventually the glue will lose its seal. The side windows seemed to work ok, but the rear needed bracing so as not to wobble around. Also, expect that within a year you'll end up replacing it again as it'll get scratched and start to look like crap.

My current thought is to use some sort of foam sealing tape and then rivet the window in. If you ever plan to use that window as an escape hatch, avoid using the button-head rivets and go for the smaller ones.

Dave

I don't think RA / competitors would ever stop him from entering/ racing in the event.

the first time Burke beats a "professional team" we could see a protest or something though. would uber suck to get a great finish erased for a minor oversight like that.

Like at least years Desert Storm Rally, lauchlin was there in a Vermont Sports Car. Had Burke won (and he won overall on a few stages) I could see a (remote) chance that someone protests / inquires his car.

ya its pretty minor though and really close. with in .00x what ever... its the same if you converted to English measurements...

I believe its m10 lexan. There are different grades any way. I use m10 on the windshield it holds up very well and I dont think you will have to worry to much about scratches with that stuff its pretty durable but it also cost more. You could limo tint the stuff then it would always look good and be .010 thicker.

if it was wobbling around, 3/16" might help with rigidity, I wasn't planning on fab'ing any other kind of supports.


how easy/difficult is it to cut?

Also....where do I find the 'm10' stuff? I'm google searching it and I'm finding references in other threads, but can't find a place to buy it.

thx



Edited 1 time(s). Last edit at 07/27/2011 05:43PM by Jon Burke.

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Reamer
I believe its m10 lexan. There are different grades any way. I use m10 on the windshield it holds up very well and I dont think you will have to worry to much about scratches with that stuff its pretty durable but it also cost more. You could limo tint the stuff then it would always look good and be .010 thicker.

That's a Brilliant Idea

1) increase thickness
2) tint is nice in the south west
3) put the tint on the outside, once it gets scratched just replace the tint , not the lexan.

Rivets suck. At least I personally hate seeing the broken lexan where the rivet cracked it. I also really hate drilling out rivets. Which is why I used stainless button head socket screws and wing nuts. I think I'll switch to stainless rivnuts or similar next time though.