My windshield moldings don’t fit correctly

Question:

In the course of doing some bodywork, the windshield of my 1966 Chevrolet Corvair was removed and replaced. Now I notice that the stainless steel reveal molding on the outside doesn’t fit right anymore, and the plastic moldings on the inside don’t cleanly and completely cover the joint between the body and the glass any longer. The layer of black sealing material (urethane, I’m told) looks a good deal more prominent than anything I remember about the original installation.

I have the body manual for my car and it specifies the use of three different sizes of rubber blocks (with GM part numbers) to position the glass. The glass shop says they don’t use these, except for two blocks at the bottom of the windshield. I can’t find the setting blocks on the Internet, although I did find an Auveco “universal” block that doesn’t match any of the three in the manual that I have. Is it important to use all of these blocks for setting stationary glass? Is urethane (which as you probably know was not used in the ’60s) an acceptable choice for setting glass on a 43-year-old car?

Answer:

If the inner and outer windshield moldings used to fit well and now don’t, it’s apparent that the windshield was not put back into its former position. The glass shop uses two blocks at the bottom of the windshield to prevent it from slipping down before the urethane sets. This is very commonly done and is the correct technique but, of course, it’s important that the blocks are sized correctly so the windshield is held in the correct location. With properly sized blocks at the bottom, the windshield will be in the correct position up and down but it may not be correctly positioned side to side.

Normally, the installer measures or eyeballs the glass to get it centered in the opening. Then, of course, there’s the spacing “away” from the windshield frame.

If the glass is not spaced within an appropriate range you will have problems with the fit of interior and/or exterior molding. I can’t say with any degree of accuracy what exactly, if anything, is wrong with your windshield positioning without seeing it or without more detailed information about the way the moldings fit (simply saying it “doesn’t fit right” doesn’t really say much).

However, if you are convinced the moldings can fit better because they used to fit better, and no other variables were changed (for example, different moldings or different glass) then the solution is to remove and reinstall the windshield. You can buy a set of rubber spacer blocks from Clark’s Corvair Parts (corvair.com) but even with those I suggest test fitting the moldings before gluing the glass in place. If need be, trim the blocks until the glass is positioned for the best fit of the inner and outer moldings.

Unless you want to replicate the exact factory configuration, urethane is an acceptable choice for installing automobile glass regardless of the age of the car. It forms a strong but flexible bond and does an excellent job of sealing against water leaks.