Jeff Ford
September 1, 2001
Contributers: Jeff Ford

Step By Step

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The center of the window opening should be established and the perimeter of the glass cleaned with soap and water, followed by a product such as PRE from Eastwood or some other degreaser.
Next, the closed-cell foam is placed on the rear window ledge. Measure the window opening and unroll the foam to create an overlap for the window opening, then fold the foam to create two even halves. Peel away the protective tape from the center point and lay it onto the ledge. Note, you may need to cut and peel away some headliner material to allow some of the foam to sit on the paint.
This is how the foam should be positioned. The corners (arrows) should be V cut. Avoid cutting them all the way through, in order to leave some material as a water barrier. Butt the two ends together at the center and weld them with 3M 80801 weatherstrip adhesive.
We installed the weatherstrip onto the glass dry, but first we cleaned the glass with degreaser. Make sure the glass is firmly seated in the corners and is even all the way around; it shouldn’t be tight on a side.
Here we’re showing you that you should never use twine. We prefer to use nylon string to install glass, because it works very well on the car due to its slippery nature. Even so, the line should be installed all the way around the perimeter of the glass. There should be two even lengths of string that you tape to the inside of the glass.
At this point, you should install your new clips. Make sure you get the correct clips. They’re available in several lengths, though typically you’ll need those that look like these shown that are 1/2-inch long. We say typically because we experienced a problem with this car later.
It’s buddy time! Get a friend to help you lower the glass into position, but now is not the time to have Fred “The Klutz” help. Steady hands and nerves of steel are required here since new glass is unavailable and the old stuff is expensive. One person per side is the best way to lower the glass into position. Once you’ve laid the glass in, measure the side-to-side clearance and the top clearance. This will probably vary somewhat from car to car. Just make sure the glass is centered.
After the glass has been positioned, your buddy should apply pressure to the glass and work from side to side. Get the string to the lower edge corner (arrow), then move over to the other side. While working your way around the glass, have your assistant apply mild pressure to the glass as shown.
You may have instances as we did where the weatherstrip doesn’t want to seat and instead “flips” back outside the car. To remedy this, we slipped a cotter pin removal tool along the section of the weatherstrip that isn’t lipping correctly.
As you round the corner, pull both sections at once. Then you should have a good lip. With the foam installed, we found that the weatherstrip fit is much tighter than in previous installs without the foam.
After the install is complete, the fun really gets going. You’ll need to slap the glass down to seat it into position. This requires a flat hand slap as shown, so it’s not for the fainthearted. In fact, the owner left the shop at this point.
Once the glass is in, caulk the glass side and the window side of the car all around with a good butyl window caulk. As Jim Smart said in our weatherstrip story last month (“Soft Parts,” page 59), you don’t want something that will take and keep a permanent set, making back-glass trim removal nigh on impossible.
Live and learn. We found ourselves in a predicament. When installing the anodized aluminum trim pieces, we realized that the car has new quarters and the pins are set too low. Sigh. We now have longer clips in position and the moldings fit just fine.
The glass is ready for any show now. All it needs is a good wipe down every time it’s washed and it’ll stay as good-looking as it is here.

Back glass on a ’71 SportsRoof can be tricky. It tends to do two things extremely well: One is leak and the other is bleach out the back seat and the package tray. Too often, we’ve seen these “skylights” with cracked weatherstrips that lead to warped package trays or rotted floors in the trunk.

Now we’re not saying the Ford install will work any better than any other install, but there’s a difference, and in some respects, it’s a major one. If you look at your Ford assembly manuals, you’ll find that they used closed-cell foam on the metal edge of the back-glass opening. Ford even gives dimensions and placement for the foam. The foam, when used in our install, tightens up the weatherstrip and hopefully makes for a better seal. This process was most likely used on other SportsRoof and fastback models as well.

For our weatherstrip, we turned to our good friends at California Mustang. Some of our other products, such as the closed-cell foam, was purchased at the local hardware store. Note, you may have problems getting the exact width and height foam, but something approximate can be adjusted to work quite well.