How To Replace Window Glass
Here Are Some Tips For Purchasing And Installing Vintage Mustang Windshields, Backlights, And Side Glass
When we began restoring a '66 Mustang, glass replacement was the farthest thing from our minds. As a rule, we've always opted for the best used glass we could find. Original Ford Carlite glass is the best option when it can be found and salvaged for restoration use. Finding good Sun-X tinted Carlite glass for this Mustang project was anything but simple-the glass we found wasn't in show condition. Qualified glass shop talent can polish out minor scratches, but deep ones can't be removed. What's more, delaminated (fogged) windshields can't be saved.
To understand what you're going to need for your classic Mustang, you have to understand automotive window glass. There's only a handful of manufacturers remaining.
Ford's Carlite glass division has been making automotive glass for more than 80 years. The name first appeared in 1959 when it became an integral part of Ford's Parts & Services Group. That's when "Car Lite" was stamped on all Ford vehicles; it soon became one word. During the '90s, it shared space with Ford's oval logo on most factory-installed glass. When you purchase Carlite glass for your classic Mustang, you can see either or both logos.
In 2000, Ford's Carlite glass division was combined with other parts divisions to become Visteon Corpora-tion, a Ford Motor Company parts spin-off company. A year ago, the two companies agreed to transfer 23 former Visteon operations into a limited-liability holding company known as Automotive Component Holdings. This more or less got Ford out of the parts manufacturing business so it could shop for competitively priced components for new vehicles and its parts pipeline.
Carlite retains sole authorization for distribution of original equipment parts for Ford dealers and auto glass professionals. The brand is still the best choice for your vintage-Mustang glass needs.
The glass can be ordered and purchased from virtually any Carlite dealer in the United States, including your Ford dealer. For classic Mustangs, it gets trickier. The windshields remain available for '65-'70 Mustangs in all body styles. For '71-'73s, only hardtop and convertible glass is available. Carlite was investigating tempered glass for all classic Mustangs at press time.
Pittsburgh Plate Glass (PPG) has been producing glass for more than 100 years. As you might imagine, the company is a huge producer of automotive glass, including laminated and tempered glass for vintage Mustangs.
When we contacted Barry Hawks at Muscle City Glass in Apollo Beach, Florida, we learned a lot about what's available for classic Mustangs. Barry opened his business out of shear frustration when searching for glass for his '64 1/2 Mustang convertible. Properly marked and date-coded genuine Carlite glass is available from Muscle City Glass. In fact, a complete '65-'68 Mustang hardtop glass package is available for $999, plus shipping and handling. N.O.S. glass is also available when found. Expect to spend more for N.O.S. Carlite glass, etching, and date coding. The average price for new date-coded glass for your classic Mustang is $1,200 for the entire car. Fastbacks may cost more; convertibles may cost less.
If you're going to have your glass date-coded, be very specific about where you want the Carlite logo and date coding positioned. If you don't, it could wind up anywhere.
Because Barry wants his customers to be happy with their glass purchase, he needs to know about the restoration and what's expected. Customers can't simply place an order and expect genuine Carlite glass. They must be very specific about the kind desired: clear or tinted, Carlite or another brand, and whether or not it should be date-coded.
One of the biggest complaints we receive from readers is windshield and backlight leakage. In nearly 30 years of publishing, we've spoken with with all kinds of glass installation professionals and restorers. One common denominator holds true: None of them can guarantee your windshield or rear window won't leak. If you own a classic Mustang with a rubber gasket windshield or backlight, count on some kind of leakage. If it doesn't, you're fortunate; if it does, you're not alone.
For windshields and backlights to be leak-free, you need a perfect bond between rubber, sealer, and surface. This takes close examination of all surfaces before installation. Any irregularities must be corrected.
Your Mustang's roof and A-pillar seams aren't perfect. They were spot-welded together at a clip of about 60-75 units an hour at peak production. Each spot-weld depression is a potential leak-and there are dozens of them. Your objective is to minimize these irregularities. If you're doing bodywork and painting-or even replacing a windshield-fill spot-welds with body filler; then sand them smooth before priming and painting. Once you do that, the next obstacle is the reproduction rubber gasket and replacement glass. Neither is perfect. Replacement glass is thinner than original equipment. Reproduction gaskets, similar to original-equipment Ford gaskets, can be irregular, causing leaks. That's why proper use of the correct sealant is so important.
According to the Ford Shop Manual for windshield and back-light replacement, it's messy and frustrating. In 30 years of working with classic Mustangs, we've tried all kinds of approaches. Here's what we learned: Ford suggests sealant between the gasket and glass. This is a good idea because flexible sealant fills in irregularities-just don't use too much.
Between the body and gasket, Ford suggests sealer in the groove. If you do it this way, it gets very messy and doesn't always prevent leakage. Based on our experiences, it's best to install the glass and rubber gasket assembly without using sealer in the outer groove. Also, use soapy water as a gasket lubricant. This allows the gasket to seat smoothly before final sealing. Firmly lean on the glass across its face to seat the gasket.
Leakage control comes from ensuring a solid wall of sealant between gasket and body. Once the gasket and glass are firmly seated, fill the area between the gasket and body with sealer. Do it in layers-down deep first-then allow it to set; next apply a second layer, also allowing time. Right before you install the window trim, lay down a top layer of sealant, leaving trim clips exposed. If you lay down too much sealant, it gets messy and the trim is hard to install.
How Is Glass Made?
Auto glass is made of sand, soda ash, coal, and other compounds that are mixed and fed into a furnace known as a glass tank. In the furnace, the compounds melt to become a molten mixture. The mix is then charged into a forming chamber known as a float bath. In this chamber, molten glass is cut off from the atmosphere, floating in a bath of molten tin (metal). During this process, glass is stretched to the thickness and width desired, then cooled until solid. It goes through a process of cooling and heating until it reaches the consistency desired. At this stage, the glass is a huge sheet about 700-feet long, ready for cutting and shaping. It's scored where necessary for cutting into a manageable size for automobiles.
Side and backlight pieces are made of tempered plate glass. It's very hard and explosive when broken, shattering into hundreds of pieces. Tempered glass is formed out of the glass-making process when it's molten and ready for forming. Edges are smoothed to make it safe. Holes are drilled where necessary.
Around 1960, automakers began installing laminated windshields in the interest of safety. It's layered-a sandwich of glass with PVB plastic in the middle. During an accident, it starbursts and cracks, but it stays together to prevent injury.
A Word About Sealers
John Sloan at The Eastwood Company set us straight on windshield sealer. There are two basic types-soft and hard. Rubber gasket windshields and backlights call for the soft stuff known as 3M Windo-Weld Resealant (PN 08634), which is the nastiest sealer to work with. It's black and gooey-use it sparingly and watch where it drips. Despite the mess, it seals well and cures to a flexible consistency. It moves with the glass and gasket without cracking and tearing.
For glue-in windshields and tempered side windows, use 3M's Windo-Weld Primerless Super Fast Urethane (PN 08609). Super Fast Urethane is a glue and sealant. When it cures, it bonds like no other. Count on security and sealing with this. Don't use Super Fast Urethane on a rubber gasket windshield or backlight. Use it only where glass is to be glued in place, such as tempered-glass side windows.
Another brand of sealer for rubber gasket windows is R900 from Adcoseal, available from most autobody paint supply stores. It works the same way as 3M's Windo-Weld Resealant. It's nasty but effective if you use it properly.
Wing, side, and quarter-window glass replacement is straightforward once each assembly is removed. Due to space restrictions, we can't go into the step-by-step removal and installation, although we show how each window type is assembled. Quarter-window glass is easy to replace once you get it out. The quarter-window frame is a combination of stainless steel, chrome-plated die-cast metal, and rubber. A flexible gasket provides a cushion between the glass and frame.