1 (edited by alloriginaltone 2022-03-06 08:32 PM)

Topic: Lexan Windshield - Screws or Clips?

Hello -

We are replacing the REAR glass with Lexan.  Front glass is staying in.  I like my OEM glass in front of my head and face.

Anyway, rear glass is out, and the lexan was cut from its template.  All looks sweet.

Now, to fasten this thing...

Could go full Lemons and line the window frame with some door gasket, use self tappers and be done...at least for a race or two.

But, I've read how lexan has some expansion/contraction properties that might fight those tapped holes and crack the lexan.  In addition the screws would be secured at a relatively narrow edge, making the hole fairly unstable.   Some have suggested the window can "float" and fasten it down with clips.

What say you?  And where are such clips...man I don't want to fabricate a bunch of bent metal clips really...

2 (edited by jimbbski 2022-03-06 10:28 PM)

Re: Lexan Windshield - Screws or Clips?

Not sure what Lemons tech wants but consider that the rear window is more likely to be sucked out then pushed in like a front windshield by air at speed. I would scuff sand the edges and use some adhesive to glue it in and then run 3 - 1" wide straps to hold it in place. Your worry of drilling holes and screws and expansion is not a problem if you use oversize holes but as you mentioned you don't have that much of a lip to attached to. The straps screw to the body above and below the edge of the lexan. Use a  nut and a bolt with large area washers to secure the straps. Not screws which can pull out.

Re: Lexan Windshield - Screws or Clips?

jimbbski wrote:

Not sure what Lemons tech wants but consider that the rear window is more likely to be sucked out then pushed in like a front windshield by air at speed. I would scuff sand the edges and use some adhesive to glue it in and then run 3 - 1" wide straps to hold it in place. Your worry of drilling holes and screws and expansion is not a problem if you use oversize holes but as you mentioned you don't have that much of a lip to attached to. The straps screw to the body above and below the edge of the lexan. Use a  nut and a bolt with large area washers to secure the straps. Not screws which can pull out.

I like this general approach.  I assume you mean  straps which run from the roof to the trunk the entire height of the lexan windscreen.  I appreciate the time taken to share the idea!

4 (edited by VKZ24 2022-03-07 08:11 AM)

Re: Lexan Windshield - Screws or Clips?

jimbbski wrote:

Not sure what Lemons tech wants but consider that the rear window is more likely to be sucked out then pushed in like a front windshield by air at speed. I would scuff sand the edges and use some adhesive to glue it in and then run 3 - 1" wide straps to hold it in place. Your worry of drilling holes and screws and expansion is not a problem if you use oversize holes but as you mentioned you don't have that much of a lip to attached to. The straps screw to the body above and below the edge of the lexan. Use a  nut and a bolt with large area washers to secure the straps. Not screws which can pull out.

I've installed four Lexan rear windows.  I use 3/16" steel pop-rivets (try installing these by hand!) and I contend there isn't a single Lemons car capable of running at speeds sufficient to "suck the rear window out" w/o using straps (required by the 'other series').  IIRC the rear window on our car has about 50 of these rivets.

Expansion/contraction has never been a problem.

Our rear window:

https://photos.google.com/share/AF1QipM … 1TdVRWbEhB

Captain
Team Super Westerfield Bros.
'93 Acura Integra - No VTEC Yo!

Re: Lexan Windshield - Screws or Clips?

People here have mentioned "scratch resistant" polycarbonate for car windows; is this what you're using?

Re: Lexan Windshield - Screws or Clips?

Lemon_Newton-Metre wrote:

People here have mentioned "scratch resistant" polycarbonate for car windows; is this what you're using?

Are you asking myself or the OP?

Captain
Team Super Westerfield Bros.
'93 Acura Integra - No VTEC Yo!

Re: Lexan Windshield - Screws or Clips?

Just mentioning the subject as a consideration; I didn't know there was a difference before I acquired a bit of polycarbonate to use for windows, but if cleaning windows needs to be done frequently I'm told they might haze over.

I have no personal experience, I'm just relating what was mentioned earlier.

And now I have plenty of extra, not-scratch-resistant polycarbonate; enough to do part of a small greenhouse, or a window wall

8 (edited by VKZ24 2022-03-07 08:45 AM)

Re: Lexan Windshield - Screws or Clips?

Lemon_Newton-Metre wrote:

Just mentioning the subject as a consideration; I didn't know there was a difference before I acquired a bit of polycarbonate to use for windows, but if cleaning windows needs to be done frequently I'm told they might haze over.


Not sure if ours is "scratch resistant" or not, but we've never had it haze over.  Being as it's the rear window, it only gets cleaned once or maybe twice per race.   FWIW, we paid about $120 for a 4'x8' sheet.

Captain
Team Super Westerfield Bros.
'93 Acura Integra - No VTEC Yo!

Re: Lexan Windshield - Screws or Clips?

alloriginaltone wrote:

Hello -

We are replacing the REAR glass with Lexan.  Front glass is staying in.  I like my OEM glass in front of my head and face.

Anyway, rear glass is out, and the lexan was cut from its template.  All looks sweet.

Now, to fasten this thing...

Could go full Lemons and line the window frame with some door gasket, use self tappers and be done...at least for a race or two.

But, I've read how lexan has some expansion/contraction properties that might fight those tapped holes and crack the lexan.  In addition the screws would be secured at a relatively narrow edge, making the hole fairly unstable.   Some have suggested the window can "float" and fasten it down with clips.

What say you?  And where are such clips...man I don't want to fabricate a bunch of bent metal clips really...

I'd used rivets and window glue...it will never move.

"get up and get your grandma outta here"

Re: Lexan Windshield - Screws or Clips?

VKZ24 wrote:
Lemon_Newton-Metre wrote:

Just mentioning the subject as a consideration; I didn't know there was a difference before I acquired a bit of polycarbonate to use for windows, but if cleaning windows needs to be done frequently I'm told they might haze over.


Not sure if ours is "scratch resistant" or not, but we've never had it haze over.  Being as it's the rear window, it only gets cleaned once or maybe twice per race.   FWIW, we paid about $120 for a 4'x8' sheet.

I paid about twice that. But it turns out I got two sheets, they're way thicker than any polycarbonate in the home stores, and they're 10x5; yet, not scratch- or UV- resistant. So I'm thinking: better for greenhouses.

I found a lot of information (some of which might be less-than-useful):

I'm looking at the bending heater here (because I think I need another few projects):

https://www.tapplastics.com/product/sup … s_supplies

and there's more input about polycarbonate here (though I think these applications are in a different economic range than a budget racecar):

https://www.trawlerforum.com/forums/s32 … 40944.html

Re: Lexan Windshield - Screws or Clips?

FWIW, these are the rivets I used.  Aluminum body with a steel pin.  If don't think they are strong, just try using a hand riveter to install them.

Captain
Team Super Westerfield Bros.
'93 Acura Integra - No VTEC Yo!

Re: Lexan Windshield - Screws or Clips?

I've used a combination of sealant/glue and pop rivets on a miata hardtop and its been good for about 4 years now. The pop rivets would probably be more than enough if it was 100% race car. I used a metal/rubber washer (don't know the technical name for it) under the head of the rivet to help seal the holes but it probably also helped mitigate cracks propagating from the hole in the lexan.

Full Ass Racing
#455 Piñata Miata - 1990 Miata
#735 BMDollhÜr 7Turdy5i - 1990 735i

Re: Lexan Windshield - Screws or Clips?

Front and rear windows are polycarbonate.  Neither is scratch resistant.  We have used a polish for the front a couple of times to improve it after some use. 

Both are attached with sheet metal screws.  Both have a vertical brace in the middle.  Neither has been an issue in 13 races.  Very handy if you want to remove it.

Organizer's Choice Award 2011 Heaps in Heart of Texas
IOE 2012 North Dallas Hooptie
2014 ECR Class C WIN;  2015 MSR Class B WIN
Speedy Monzales

Re: Lexan Windshield - Screws or Clips?

VKZ24 wrote:
jimbbski wrote:

Not sure what Lemons tech wants but consider that the rear window is more likely to be sucked out then pushed in like a front windshield by air at speed. I would scuff sand the edges and use some adhesive to glue it in and then run 3 - 1" wide straps to hold it in place. Your worry of drilling holes and screws and expansion is not a problem if you use oversize holes but as you mentioned you don't have that much of a lip to attached to. The straps screw to the body above and below the edge of the lexan. Use a  nut and a bolt with large area washers to secure the straps. Not screws which can pull out.

I've installed four Lexan rear windows.  I use 3/16" steel pop-rivets (try installing these by hand!) and I contend there isn't a single Lemons car capable of running at speeds sufficient to "suck the rear window out" w/o using straps (required by the 'other series').  IIRC the rear window on our car has about 50 of these rivets.

Expansion/contraction has never been a problem.

Our rear window:

https://photos.google.com/share/AF1QipM … 1TdVRWbEhB

Another excellent contribution.  Thank you.

Re: Lexan Windshield - Screws or Clips?

rcazwillis wrote:

Front and rear windows are polycarbonate.  Neither is scratch resistant.  We have used a polish for the front a couple of times to improve it after some use. 

Both are attached with sheet metal screws.  Both have a vertical brace in the middle.  Neither has been an issue in 13 races.  Very handy if you want to remove it.

Do you have any sealant or gasket between the polycarbonate and the metal flange on the car to snug it down, keep it semi water tight and non-rattley

Re: Lexan Windshield - Screws or Clips?

VKZ24 wrote:
jimbbski wrote:

Not sure what Lemons tech wants but consider that the rear window is more likely to be sucked out then pushed in like a front windshield by air at speed. I would scuff sand the edges and use some adhesive to glue it in and then run 3 - 1" wide straps to hold it in place. Your worry of drilling holes and screws and expansion is not a problem if you use oversize holes but as you mentioned you don't have that much of a lip to attached to. The straps screw to the body above and below the edge of the lexan. Use a  nut and a bolt with large area washers to secure the straps. Not screws which can pull out.

I've installed four Lexan rear windows.  I use 3/16" steel pop-rivets (try installing these by hand!) and I contend there isn't a single Lemons car capable of running at speeds sufficient to "suck the rear window out" w/o using straps (required by the 'other series').  IIRC the rear window on our car has about 50 of these rivets.

Expansion/contraction has never been a problem.

Our rear window:

https://photos.google.com/share/AF1QipM … 1TdVRWbEhB

I don't dispute that but the OP said there was a very small lip to attach the rear window to which means that he would have to drill holes very close to the edge of the lexan.

Re: Lexan Windshield - Screws or Clips?

I would just remove it and not replace it.    Cant scratch what isnt there!

Re: Lexan Windshield - Screws or Clips?

alloriginaltone wrote:
rcazwillis wrote:

Front and rear windows are polycarbonate.  Neither is scratch resistant.  We have used a polish for the front a couple of times to improve it after some use. 

Both are attached with sheet metal screws.  Both have a vertical brace in the middle.  Neither has been an issue in 13 races.  Very handy if you want to remove it.

Do you have any sealant or gasket between the polycarbonate and the metal flange on the car to snug it down, keep it semi water tight and non-rattley

Yes, cheap foam weather stripping stuck to the metal.  Screws through windshield, through weather stripping and into the metal.

Organizer's Choice Award 2011 Heaps in Heart of Texas
IOE 2012 North Dallas Hooptie
2014 ECR Class C WIN;  2015 MSR Class B WIN
Speedy Monzales