I’m dedicating this post to “setting the glass.”

What exactly is meant by setting the glass? Setting the glass refers to placing the glass into the opening on the vehicle’s body where it is meant to fit. Some glass parts are adhered to the frame (pinchweld) and others are mechanically fastened and attached with nuts and bolts. The adhered part uses adhesive to bond and seal the opening from weather related issues, while the mechanically attached parts use a sealant.

Proper glass setting is imperative to sealing and bonding success. The amount of clearance in many cases, from top to bottom and from left to right are less than ¼ inch. The most important and difficult part to set and manipulate is the windshield. Due to its size, awkwardness, and importance to safety, the windshield gets all of the attention when it comes to accurate placement.

To properly set a glass into an opening, it is imperative to have access to all sides of the glass part and the opening. Tucking the glass under the cowl panel is not an acceptable procedure.  The technician cannot see the lower bead contact the adhesive and cannot correct a displaced bead after setting it because of the cowl panel’s presence.

There are many procedures and tools available to aid in setting the glass. Some may take extra effort, more practice, or additional cost than others, but the choice is that of the technician.

Once the glass is set in the opening and on the adhesive, the next step is to “deck” it out and make the seal. This is accomplished by the firm but gentle depression of the glass into the opening. How far into the opening the glass is depressed is important, if it’s too far and the glass could be susceptible to stress cracks. On the other hand, if it’s too little, and the glass will not perform its safety role in a crash.

The ideal positioning in the opening is dependent on the style of the vehicle. In a vehicle equipped with exterior mouldings the outside glass surface should be tight against the underside of the exterior mouldings and spaced high enough from the interior mouldings to prevent unpleasant noises.

If the glass has an exposed-edge style of mounting, then the glass positioning should be slightly lower than flush with the roofline. If it’s flush with the roofline, the glass and body can cause a noise called the “flute” effect. The air blows over the gap between the glass edge and the wall of the pinchweld causing a whistle or air rush noise. If the glass is too high, then the windshield will not support the roof to FMVSS 216a required for safety. If the glass is decked too low and the glass loses its freedom of movement and can cause stress fractures.

Setting the glass is vital to the success of the installation and must be accomplished flawlessly every time. Do not take shortcuts with this step.