Jerry wrote:
I was only thinking side windows, and mostly for the weight of the glass + motor. The back window is tiny (not savings), and not sure I'd go full-on for the windshield.
Hmmm as Yoda would say I must meditate on this. (Sorry, got Star Wars on the mind while I search Jedi costumes for Halloween.)
Good call. You'll get a LOT of weight out of the doors. My brother copied Guido's design for one of our Challenge cars. Gut the WHOLE door but leave the crash bar (nibbler works really well for this, in conjunction with sawzall and grinder,) Use the old window as a template for the new one. If you're a big pimp, HEAT form the lexan window to match the curve of the "real window," then bend a full frame for it out of ready rod or something similar, with two "posts" at the bottom. Drill holes in the crash bar, or mount a couple tabs to it to accept the ready rod, nut the rod to locate the window. Worked surprisingly well. A little "pop in" clip at the top would be pretty boss too.
We use these little threaded rubber grommets on the Trans Am cars. You drill a hole (forgot the size, something like a 3/16 bit) and use a pick to pull these rubber grommets through the hole. It has a threaded insert inside the grommet, so you screw it on.
I'll try and remember where we get the grommets from, think it's McMaster-Carr
In reply to DukeOfUndersteer:
Well nuts?
http://www.mcmaster.com/#well-nuts/=og97lb
when it rains at the track, sometimes the crew chief can be seen running to the car with windows :)
GameboyRMH wrote:
Lexan's a monster PITA on a street-driven car (due to extreme scratchability if nothing else). On anything but a dedicated track car, I wouldn't even consider it.
What he said.
Glass is really, really nice because of that. And, on typical Japanese cars of the 80s, the glass is pretty light to begin with, so it's a minimal weight savings with major downsides.
You'd probably save more weight by scraping dirt out of the fenderwells between heats.
Jerry, building a full set for the Rustang as we do this, the biggest challenge building them is finding a big enough oven to get the curve on the front and rear glass.
I did the 1/4 windows in the shop oven.
I am going to a local power coater this Saturday to get these sorted out.
I have found 300 to 325 degrees is a good temp to get them to curve at a controlled rate, but thickness and brand can change this, so YMMV.
ncjay
HalfDork
9/11/13 5:19 p.m.
All I have to say about Lexan windows is that in my experience, they aren't worth the effort on a car that sits outside in the weather all the time. A garage kept car could probably get away with it. It's also a good idea to fabricate a system with quick & easy replacement in mind.
Jerry
Dork
9/11/13 6:35 p.m.
In reply to ncjay:
This would be garage-kept. But I'm sensing an overwhelming disturbance in the Force to NOT do it.
Jerry wrote:
In reply to ncjay:
This would be garage-kept. But I'm sensing an overwhelming disturbance in the Force to NOT do it.
It'd be different if it wasn't rallycross. They'd probably be okay until the first time they got dirty.
Can you buy tear-offs for Lexan, like helmets?
At least for a track-only car, that might be a way to get the surface to last a lot longer?
I say go with the stock glass and hooks to hold it up.
or just turbo and you won't notice the extra weight.
EvanB wrote:
I say go with the stock glass and hooks to hold it up.
or just turbo and you won't notice the extra weight.
Turbo is not an option for a few reasons. The amount of HP I'd make would put me in a very high TT class.
It takes cubic dollars and a lot more work to make a turbo track car anywhere close to as reliable as an N/A car.
JoeyM
Mod Squad
9/11/13 9:36 p.m.
Leafy wrote:
Yes, but $35 includes the "I'm incapable of making E36 M3" tax.
This is the most accurate summary of cars - life in general, actually - that I have ever seen.
wclark
New Reader
9/12/13 7:17 a.m.
In reply to Jerry:
I replaced the side and rear glass on my '86 GTI hillclimber with polycarbonate after experiencing a lot of window shattering during a rollover. My goals were both lighter weight and some added safety.
I went with a poly carbonate that was slightly thinner than the stock glass to shave a few added pounds.
I have full window frames on the doors and by leaving the channel "felts" in place I provided a support for the perimeter of the polycarbonate. After working with with the sheet I would guess a frame-less door would require a polycarbonate thickness much greater than stock glass to be rigid enough to stay in place while being buffeted by wind, say during towing. That would negate most of the weight savings. And the thicker poly would probably require heat shaping, where the thinner-than-stock-glass stuff I used easily conforms to the shape of the tracks in the doors.
I gutted the doors of everything but I left the perimeter of the inside frame in place and use a nylon strap and Lift-the-Dot® fastener to secure each door window from a stiffening spine along the bottom of each window to the top-inside door frame (window sill). The strap idea is borrowed from some cars of old where that was the provided window lift mechanism.
The rear and rear side poly is installed in the original rubber window channels (trimmed down to eliminate unnecessary material) as that turns out to weigh about the same as the seal tape, and screws needed for a more typical race car install. It is also is easier to remove and reuse or replace the poly and avoids the stress cracks often accompanying a screw-in solution.
With the thinner polycarbonate I added aluminum stiffening struts from the bottom to top of each fixed window to reduce "drumming" that occurs when the car is wind buffeted and help them follow the contour of the original glass. I used 1 strut in each rear-side glass and 2 in the hatch. These are 3/32" x 1" hard alloy flat stock that I shaped to the proper contour then attached to the inside surface of poly windows with 3M industrial strength double sided tape.
Just make a frame if its frameless. Side curtains come to mind.
z31maniac wrote:
Can you buy tear-offs for Lexan, like helmets?
At least for a track-only car, that might be a way to get the surface to last a lot longer?
Yeah tear-offs are very commonly used on Lexan. You must protect it with something or it will scratch like butter.
The other options are long-term-use clear film coatings, and big $$$$ ceramic coatings.
I would ask Karl about tear-offs, that is his business, isn't it?
Karl La Follette (sic) one of our GRMers has a business supplying tear offs to race teams.
http://racetearoffs.com/
Yavuz
Reader
1/29/15 10:18 p.m.
Apologies for bumping up an old thread, but I found this while looking into those $35 window clips.
Can you actually drive around with a window held up by those if you were to have a hardtop on the car? Or are they simply for storage and transport? My car is currently topless and windowless, but I may get a hardtop soon and am wondering about using it in the rain.
I have lexan on the rear door windows of the rallycross e30 (each with a pair of aircraft-style circular pop-out vents). By removing the glass, window mechanisms, motors, and related stuff I saved nearly 40 lbs. all told....old motors are heavy, as is glass.
They're riveted into place and after about 18 months sitting outdoors no appreciable yellowing or scratches (not that I really care anyhow).
Easy to cut, easy to install, less weight, I don't see a downside since I don't need to open those windows anyhow.
How about making windows out of the clear plastic that they use on convertible tops. You can hold it in place with some snaps. Old school British cars had them. They were called side curtains.
