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The text following is part of a series of articles written by John S. Henry on the restoration and maintenance of air-cooled Volkswagens. While his experience is exclusively with the Beetle, many of the techniques can be applied to other models.

This text is copyrighted and duplication, re-distribution or publication is prohibited without consent of the author.

Article: Installing Fixed Windows in the Beetle
Last updated: 10/30/01

Installing Fixed Windows in the Beetle

Symptom: You removed your windshield, rear or rear quarter windows to paint and install a new headliner, and you hadn't really thought too much about how you are going to get them back in.

I feel compelled to write technical help articles sometimes not because I have years of experience with the subject, but because perhaps I have just spent some real frustrating days and weeks trying to do something that was new to me; and learned some difficult lessons. So I do not have years of fixed window installation experience with Beetles, but I helped my brother put a windshield in and went through almost a month of effort trying to get the front and rear windows in my own ’57 Beetle (to read more about those specific trials, check out page 20 of the ’57 resto series). So this article deals with fixed window (windshield, rear and rear quarter, non-pop out windows) installation in the Beetle and pays particular attention to the installation of the aluminum molding found on the early Beetles. But I would guess that many of these techniques would also apply to other models as well, both VW and non.

Note: Read this whole article before starting

Basics

The fixed windows are held into the body by a rubber seal which is slotted on the inside of its circumference to accommodate the glass, slotted on its outside circumference to accommodate the flange in the window opening of the body, and most have a thin slot around their outside face to hole trim molding. The seal is placed on the window, the molding is placed in the seal groove and the window is then placed in the body opening. It would be great if it were that simple, but it is not….

And in case you were thinking about it, it is not possible to put the molding into the seal after it and the glass are in the car.

Do the numbers make sense?

After my first attempts at putting my windshield failed, and calm returned with logical thought, I analyzed the situation like any engineer would: glass + seal < opening in body This after my failed attempts seemed to indicate that for some reason the whole glass/seal/molding assembly was just too big to fit in the window opening. It really a wasn’t, but the engineer in me took the time to take some measurements before I continued. Since there are several types of seals and window glass that looks very similar but is for different year ranges, it may very well be worth your time, if at least for you own sanity, to take some measurements before you begin. The math is very simple. The dimension of the glass, plus the thickness of the seal, minus the depth of the groove in the seal for the glass times two, must not be (much) greater than the opening in the body. This would be the opening in the body in which the entire seal fits, not the opening between the flange edges in the body. I don’t recall the exacts numbers, but doing this math on the windshield of my ’57 showed that the seal installed on the windshield would be slightly less than 1/8" (about 3mm) larger than the opening in the body. This true at both the top to bottom distance in the center of the opening and side to side, at the glass’s widest point. In spite, the glass went in rather easily.

Worktable

One of the things I found real useful when setting up these windows for install, was a rolling work table that I use in my garage. And more importantly, the pedestal on top of it. That is, I put about an 18" piece of 2x6 on the top of the table and covered the whole thing with an old blanket. This allowed me to place the windshield on top of the 2x6, and have the edge raised up all the way around. If you try install the seal and molding on a flat surface, you will find that the seal may get pulled off in places as you move the glass around while working on it.

Installing the Seal

If you have an early Beetle, and will use the aluminum molding, placing the seal on the glass, and the molding in the seal will be 60% of the job. Really. Take you time (allow time) for this, you might do it a day or two before. The first time I did this, I spent an hour just getting the seal on the window (then many months later realized I had put the glass in the wrong groove; read on...). Don't make the mistake I made:

It is possible to flip the seal over, install the glass in the molding groove, the molding in the glass groove, wrap the cord behind the lip that is supposed to out outside the car, and pull that lip inside the car. This is bad, don't do this.

If you read this article between October 1999 and July 2000, you might have read about all sorts of problems I had getting the seal to stay on the curvature of the glass, and how I had to glue it. Well of course!! The molding seal is "bent", and has a rounded bottom. Try to shove a fat square edged glass in there, and it will creep off!!! LOOK at you seal. See two grooves? Open them up and look inside. One is deep and has a very square bottom, it also has some little ridges on both sides part way down. The other is narrower, and rounded at the bottom, and actually isn't straight. I have saved a cross-section of my old seal and will take a picture of it and add it to this page soon.

Don't make the same mistake I made! I cost me a new windshield and $60 in new seals and moldings.

Moldings

It may seem like it is easier to put the molding in the seal before the seal is put on the glass, and it is. But it is all but impossible to get the seal on the glass then. Especially with the aluminum moldings, it is critical that they have just the right bend in them to match the contour of the glass. As it turns out, the molding groove is almost exactly over the glass edge in the seal when it is all installed. Thus, the bare glass edge makes for a perfect template to insure that the aluminum molding is the proper shaper prior to trying to put it in the seal. With the plastic moldings used in the later years, this is not so important.

New aluminum moldings come roughly bent to shape, but they must be tweaked to fit in a seal installed on a window and to look right when the whole deal is in the car. The aluminum is soft and bends very easily. Before you put the seal on the glass, lay the new (or old) molding pieces on the glass and use it (the glass edge) as a template to bend the molding to perfect shape. It must follow the curve of the glass edge exactly and lay flat. Take you time, bend a little, test, bend some more, test, etc. Be careful to make only smooth, gentle bends, not sharp ones. The sharp corners on the lower end of the windshield are the hardest.

There is a right and left side of the windshield molding (the other window’s moldings are one piece). Look closely at the end of one of the pieces and you will see. The cross section is like roughly ¾ of a circle. If you get the sides right, about ¼ of that circle will be in the groove, and about ½ of the circle will be out. If you get them backwards, it is pretty obvious. And another thing about moldings. If you bend too much, and basically reposition the curves (corners), the points where the two molding pieces meet (and are joined by the little clips) may not be I the longitudinal center of the car. If you are a perfectionist, you would never be able to live with trim clips that are off center (one would be right of center, one left of center). See what I mean? What I do is measure and mark off a vertical line down the exact center of the windshield with a marker. It will help you keep things straight. It is pretty hard to re-bend the molding enough for this to be a problem, but I did notice that my junctions were off center a bit. Fortunately, the fact a that the junction clips are wide gives you a little more than an inch of a margin of error. So tweak both pieces, keep laying them on the glass until they lay perfect, follow the curve of the glass edge perfect and the junctions, top and bottom, are in the center. It is normal for there to be a gap between the ends.

So at this point you should have your seal slipped on to the glass edge and your molding all tweaked to perfection. Lay a molding piece over the seal groove and get an idea where the ends will be. I found it easiest to start at the ends at the bottom edge. Using a blunt, non marring tool, like a Popsicle stick, or plastic knife handle, open the groove and work the molding in starting at the end along the bottom. By pushing the molding with you thumb toward the center of the glass and down, you will sort of "roll" the aluminum into the groove as you go. It will be obvious when it seats down into the groove properly.

The lower corners are the toughest part. If you started with the end at the right place, and you took the time to bend the molding to the perfect curve at those corners, it should go OK. Use the tool to open the groove and "massage" the molding down into the seal. It takes lots of time and patience. Do not use real hard pressure with your thumb, you will "dimple" the soft aluminum and it will look all wavy and ripply when you are done Do both sides, do not put the "bridging" clips in until both sides are done. Do not use a metal tool like a small screwdriver to open the molding groove in the seal as the aluminum mars very easily. I got these "glass sticks" from the guy at the glass shop that are like big, thick Popsicle sticks made of plastic but tapered on the ends.
Snap the bridging clips in and center them with a plastic or wooden tool (NOT metal!). Look at the clips closely and you will see one edge has a bit of a lip on it. This edge goes down in the seal. When you are done you should have the seal and molding on the glass, tightly and securely fitted, bridging clips in place.

The String Trick

Maybe you had heard about this before. Some people use wire (insulated) and some people think string trimmer (yard tool) cord is best. But any very strong, very flexible cord 1/8" or less in diameter, will "rope in" a window. Do not use twine, no matter how strong it seems, it will likely break. And I’d stay away from wire of any kind; too easy to scratch paint. The trick is to loop this cord around the window in the groove in the seal that will accommodate the flange in the body opening. You overlap the cord at its ends. They you get someone to press the window in from outside, while you start pulling one end of the cord. As you go, the cord is freed, and the inner lip of the seal is pulled in and over the body opening flange. When it works, it works well……

Opinions as to how to wrap the cord vary as much as the what is the best lure to catch largemouth bass. I took the advice of many, and was very successful with overlapping the string along the entire lower edge of the glass. That is the ends of a cord used on a windshield should be at the lower corners, overlapping the whole bottom edge. As you place the window in the opening initially, make sure the ends fall inside the car.

There are also varying opinions on the use of lubricants too, but most would probably agree that putting a window in "dry" is not an option. I use K-Y Jelly and plain water in a spray bottle for my windows. Some testify that soapy water will eventually harm paint. Other recommend silicone spray or talcum powder. But be careful with the back and side rear windows if you have an early felt headliner. Any liquid will be absorbed by the felt and you will likely have at least a faint water stain. Talcum powder or judiciously applied K-Y Jelly are the best options back there.

Many folks recommend warming the seal, but in normal summer weather temps, I didn't need to. But if you are working on a bright sunny day, consider leaving it in the yard or an a table in the sun before you start.
The trick is to get the whole glass and seal as much fully into the opening as possible before you begin pulling the cord. If your dimensions are all in order, the whole glass/seal/molding will slip into the opening and the inner edge of the seal will be flush with the body opening flange all the way around. If it is not, don’t bother starting to pull the cord. Pulling the cord will not pull the window into the opening if it is not already fitting in it. This is perhaps one of the biggest myths of this whole procedure. Get the whole window in the opening first, then pull the cord. The cord's only job is to get the seal lip over the body opening flange.

Do not try to slip one edge of the seal lip over the flange (top bottom or side) then push from the other side. Put the window against the body opening perfectly perpendicular to the opening and push. If the seal is seated fully, and all the dimensions are correct, the window will go in. Work the seal with your thumb, but don’t push too hard on the aluminum molding or you will distort it and it will be visible later. Prior to starting with the cord, you may also slap the glass with your open palm (take any rings off!!). The back windows are the strongest, you can actually pound those with your fist and you will not break them. But be careful with the lower corners of the windshield, this is the most common area that breaks. Do not put too much pressure on it there. Again, don’t even think about pulling the cord until from inside, you can see that the whole seal, all the way around, is butt up against the flange in the body opening.

When the window is fully seated, it is time to start pulling the cord. Start at either lower corner and have someone push from the outside on the glass just above where you are pulling; but not too hard. If they push too hard, they might make it too hard for the string to come out of the groove and/or they might break the glass (especially the windshield lower corners). Have them push just enough to insure the seal seats the rest of the way in as you go. Work across the bottom and when you get to a corner, round it and get start going up. But just as you round the corner, go back to the other side and start pulling the other end. Round that corner, then go to the other side. What you want to do is not let one side get too much farther up than the other. You might also spray some water now too to help the lip/cord go along from the inside. Work you way up the sides, over the top corners and free the cord at the top center. Warning: The glass edge, especially where you "close the gap" on the seal lip pulling is under lots of stress, do not whack it with anything (including you hand or fist) at this point. Once the lip is fully pulled over and the cord out, some additional and slapping of the glass with bare hands may be needed to fully seat the window.

Clean up the area well, of what ever lubricant you used. If you used talcum powder near a felt headliner, just vacuum, and you car will still have that morning fresh smell!
Again, for more details on my particular experiences (and mistakes!) with my own '57, check out page 20 of the ’57 resto series.

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