Technical chop top cutting windshield to size

O.k. so top is chopped. I know how to cut gl***. How do I measure it?
I measured old opening and then new opening. Cut a template to size. The template seems to tight in the new weather strip.
I am worried about cracking windshield due to stress while driving down the highway.
I can cut it to fit just don't want it to be to tight.

 

Use the windshield as a mold and make a fibergl*** one to practice getting the size and shape right.

 

***uming that you are just lopping off the top, take another 1/8" off, and put a thin bead of windshield cement on the new top edge.

That will prevent pressure, and the cement will keep it from moving.

 

Just cutting top of gl***. 1/4 inch more seems to work better

 

Look at @Lloyd's paint & gl*** thread, He likes to sand off small bits, not try to break them off.

 

I'm not sure how the real gl*** guys do it but If I had the original gl*** I'd lay it on something stiff enough to make a pattern out of, trace it out, cut it out and then cut it in two straight across and overlap the pieces in the opening to get my gl*** size. I figure to do that on the windshields and side gl*** on my 48 and then cut out 1/4 inch masonite to the size and do the fitting with it before loading the truck up and hauling it to the gl*** shop. I'm just not hard core or cheap enough to want to install my gl*** myself again.

 

Try masking with silicone and rubber tyre strips then sand blast at 45 angle . keep pressure as low as possible and just keep at it . worked for me on 59 Rambleher

 

It's like a torque spec, or boring a block, creep up on the final size with the belt sander. You've gotta sand the edges anyway to rid it of stress risers.

 

What car? Flat gl*** or curved? Flat is easy. If it is curved and you are just now trying to fit it to the opening you are already b*** ackwards. Fit should have been considered first before cutting metal.

 

My car is a 54 chevy. Curved gl***.
I brought this up because others have asked about windshield installs. Weather stripping etc.
Just wanted to help some out on chopped top windshield installs.
I had a friends crack after about 2 months of driving.
I don't want that to happen to me or anyone else.

 

Yeah Jerry, if it's under stress anywhere in the gasket, you can bet that it will crack! Gl*** doesn't bend very well lol. But after you cut it to your desired size, if it needs some adjustment, 80 grit aluminum oxide sanding belt and a spray bottle of water will move a lot of gl***. Buy you a whole pack of belts lol. And you can finish the edge with 120 or 150 seeing how it's not exposed, like the top of a door gl***. I have a $75 craftsman belt sander, and it works just fine.

 

Thanks Lloyd. I will be trying it again next spring.
I have to finish the wife's Nova first.
I'm going to order a new windshield soon. I hope to get back to working on it soon.
Work is really busy right now so not much time for cars.

 

And, don't forget your safety gear. Sanding gl*** is dicey in a handful of different ways.

-Abone.

 

I would like to reshape a curved rear back gl*** from essentially a rectangle to an isosceles trapazoid like this: The curved sides would remain but the top total gl*** width would be closer than it is right now. The lower total gl*** width would remain the same. Make any sense?


I picture 4 cuts which would remove 2 pie shaped pieces. Is this even possible with tempered 1959 gl***? If so, what kind of shop should I be looking for? (please excuse my complete lack of knowledge on gl***). thanks

 

If it is tempered, it can't be cut til its untempered. Otherwise it will just shatter. Untempering is even harder than tempering, I've read.

 

thanks... anyone had a custom curved gl*** made?

 

Unless you are chopping a car with flat gl***, you should cut the gl*** first, and fit the metal to the gl***. Unfortunately that won't work now. Through the years I have seen lots of chopped cars sold without gl*** for cheap prices cuz no one could make the gl*** fit the opening.

 

I think this is a wise idea... I just mocked up the back window with a 6" chop and I really like the look. (and putting it back together is within my neophyte skill set)... I think the process will be get the opening where I like it. Maybe a form that I can flip side-to-side so I know they are the same, then create a full size template. Not sure how I might do this... cardboard then fibergl***? Look for a custom gl*** place like this one https://www.procurvegl***.com/ or just use lexan... any thoughts?

here's the victim...

 

wetskier, a side picture would help, from the one you've posted the only option I can think of is 1970 Camaro back gl***

 

You could always sink the factory rear gl***. Then there would be no cutting involved.
A quick search brought up this thread. There are others as well.

53 chevy chop sinking rear gl*** | The H.A.M.B. (jalopyjournal.com)

 

off subject-I have a friend who works at making special gaskets-rare cars to space rockets. He has access to a hydo water cutter they can use after work. It will cut thru the gl***- steel- rubber all at once- not taken apart-perfect cut. good for reducing roadster wind shields and curved gl***. ask in your area- they are around. Not recommended to purchase- several hundred grand !

 

Could always see if you can find a windshield with similar contours to cut.

 

I had seen the references to sinking the gl*** into the trunk but I also leaned the c pillars in at the top so that method won't work for me. On donors, the closest I could find would give pretty large sail panels with smaller gl***. It would really change the looks... I did, however, have some very nice junkyard tours of older iron while looking.

Does that water hydro cutter work on tempered gl*** without shattering it?

 

No. Once you remove a bit of tempered gl***, whether it’s a small chip or grain from the edge or the middle, it will shatter. I’ve seen it explained as if the piece of gl*** is a balloon, yet a very flat balloon. Once you take a nick out of the surface of the balloon the whole thing explodes.

 

Coincidentally, I saw a motorhead show last night where they cut a new, curved windshield for a 1955 Ford pickup to fit a chop. The windshield was laminated and the process was relatively straightforward. It doesn't help me at all but it was cool to see. The rest of the truck's gl*** was all flat that they cut to size from new stock.

It's amazing to me that the little gl*** cutter tool works at all. It seems to essentially just score the gl***. The pro doing the work said he had about a 90% success rate on curved gl***.

 

I was told decades ago to do just that. Cut the gl*** first, and chop the top to the gl***.

 

ive always thought all cars from our era were safety gl***? every pane on my '57 ford is laminated.

 

Most rear gl*** was tempered in the late 40's and 50's on up.