Chopping tops and placing windshields ?

[ERIK88]

How do you guys chop a top, and manage to make the windshield fit? Since it is not the same height and shape as before? What do you do to get the windshield to match with the chopped top?

[Harry P.]

It all depends on the specific car you're dealing with. For example, most cars from the '30s-'40s have flat windshields, so if you chop the top, you can trim down the windshield to fit the new shorter opening. On some models with curved windshields, like a typical '50s car, many times you can still get away with just trimming off the bottom of the kit windshield. It all depends on the specific car and the shape of that car's windshield.

If the top chop makes the windshield opening so different that the kit windshield can't be used, no matter what, you can make a new windshield using clear acetate (found in art supply stores or the art aisle of Hobby Lobby) if the "glass" curves in only one way (not a compound curve), or you can make a buck and vacu-form new "glass," but that gets to be a major project in itself. Also, a lot of products come in clear plastic "blister packs," sometimes the packaging can be used to create the new windshield.

[bobthehobbyguy]

Getting glass to work on a chopped top for a full size car can have the same issue. Sometimes glass is used from another car or the pillars may be altered to use part of the original glass. Sometimes planning out the chop before any cutting is done will help.

[ERIK88]

Thanks guys, I'm thinking about chopping a amt 55 chevy stepside . I think the windshield is flat for the most part. I might just cut from the bottom as needed. and yea I can imagine how hard it would be ona 1:1 car! Lots of prep work

[Ace-Garageguy]

Part of what I do for a living these days involves chopping 1:1 vehicles. As noted, planning up front is extremely important. Though windshields are made from laminated glass that's fairly easily cut, it's not uncommon at all to go through several windshields when doing a chop on a significantly curved piece.

When you chop a top, usually the width of the top and bottom of the glass opening stay the same, but of course the distance between the top and bottom edges changes, This changes the angle of the edge of the opening to the top and bottom. Laminated glass will bend somewhat, but again, it's not at all uncommon to be almost home and to hear a "pop" and watch a break spread across your expensive cut windshield.

It's the change in angles at the sides that makes the problem on a deeply curved piece of glass like you find on the mid-'50s Chevy truck. And though the curve here is in only one plane, not "compound", it's still somewhat difficult.

Stock...

Chopped...

If you do a radical chop and try to take all the meat out of the glass on the bottom, it won't fit well at all. The bottom of the cut windshield will be narrower along the cut edge than the lower edge of the opening for it, and a "pop" is almost guaranteed when you try to get the glass to spread to fit the opening.

Same goes for a model, and that's why, if you want a chop to look really good, you should just figure on making a new piece from acetate or clear styrene sheet as mentioned above. The material is easily cut to shape with scissors, can be trimmed very accurately the same way, and will happily conform to your new non-compound-curve opening.

Simply make a template of the chopped opening using masking tape rough cut, put it on the flexible material, and fit, fit, fit.

Large clear or tinted "pop" bottles make an excellent source of window material. In this case, the "pop" is a good thing.

EDIT: Once again, plan first. We had a radical '49 Merc in the shop last year that had been chopped and painted before we got it. NO planning as to how to get a windshield in the thing had been done prior to painting, so this build that had already absorbed well over $120,000 was stalled indefinitely...the owner so disgusted and disheartened that a lot of his expensive work (done elsewhere) would have to be re-done entirely in order to get glass in it.

There are "cheats" to getting a windshield to fit in a poorly chopped car, like gluing it in with urethane and splitting the gasket and gluing it on as well, but the pillars in this old Merc were so misshapen that no amount of creative engineering would solve the problems.

PLAN FIRST. TEST FIT BEFORE PAINT.

Edited November 24, 2014 by Ace-Garageguy