Proper Glass Seals For Your Squarebody Chevy

Seal of Approval

Anyone who has dove into the task of doing a full restoration on a classic pickup knows that glass and weather seals can be quite the task. If you’ve never taken on the task of a restoring a truck, the glass and seals probably isn’t the first thing you think about when you consider the job. However, skimping on this part can really affect the overall quality of a build for several reasons. Obviously, you don’t want to put weathered glass and rotted seals on a fresh paint job. Also, without the right seals in place, the truck will leak water in the event of rain. Most importantly, the truck will be noisy inside the cab while driving down the road. So sealing your build right after you’ve just finished the fresh paint should be considered a must.

Although companies like Precision Replacement Parts have made some strides in easing the task with their push-on door seals, some jobs are better off left to a specialist. The toughest part of all of the glass and seals is rebuilding the vent windows. Most professional glass installers would have several specialty tools to do the job. For the DIY guy though, there’s no use buying all these tools now that Precision started its new vent rebuild program.

Precision recognized that a lot of work goes into rebuilding the vent windows properly, and that it’s a job most people just don’t want to attempt. The company is now facilitating the DIY enthusiast by offering a service that allows you to send in your complete vent window assembly. Once staff receive the windows, they completely tear them down to bare bones and rebuild them with all new seals and hardware. In this article we’ll walk you through the necessary steps to remove your windows, send them off to Precision Replacement Parts, and reinstall them after the rebuild.

The truck we’re working on is a 1987 Chevy K5 Blazer that we are building for SEMA 2018. The removal and reinstallation of these vents windows is very similar to earlier Chevy trucks as well. Precision offers this service for a wide variety of trucks and will most likely be able to assist in the vent rebuild of any classic truck.

As you can tell, we have begun working on the truck, getting it ready to head down to the body shop. We have welded up some extra holes in the doors and fixed some rust issues. We’ve also started to de-trim the truck, and the last thing we need to do is remove all the glass

Since the interior door panel is already removed, we have easy access to the windows. The roll-up window is removed first. It’s actually easiest to remove the piece of glass by passing it through the outside of the upper door frame.

The vent window is next and is held in by several screws. There is a bolt located at the base of the assembly, one screw in the front of the door, one screw in the top of the door, and one right under the vent window handle.

Once we had all the hardware removed, we slid the assembly backwards and lifted it out of the door. This takes some time, tilting the assembly, rotating it and lifting it out.

After we had both wing windows removed, we packed them nice and tight and sent them off to Precision Replacement Parts. There they would take over for us and completely restore both vent window assemblies.

Once Precision received the assemblies they got right to work. The window assemblies are held together with rivets, bolts, and some bent tabs. The disassembly process begins with the first rivet, which is removed by drilling out the head of the rivet.

Using a small punch, the rest of the rivet is tapped out to free the top pivot of the glass.

In order to free up the bottom pivot of the glass, the lower nut is removed. Before removing the nut, there is a washer with locking tabs that must be bent out of the way. Also, you can see the spring that the nut is compressing. When loosening the nut, it will remove most of the tension on this spring but it’s important not to let the spring fly off and get lost

There are quite a few pieces to remove just to free the glass part of the vent window assembly. You’re probably starting to realize why this is a job best suited for a specialized technician.

With the glass portion removed, the frame could start coming apart. A simple flat head screwdriver is used to separate the felt seal on the outside edge of the frame, where the roll-up window travels. Next the same screwdriver is used to bend the tabs, securing the inside edge seal that the vent window would seal against when closed. Finally, that inside seal is pried out and removed.

Since the frames will be getting sandblasted, every piece needs to be removed from the frame. This is the piece of trim that the window lock slides against, and it was carefully removed with a pair of pliers.


Using a plastic pry tool, or “bone” as they’re called, the metal frame around the glass is removed. This is held in place with rubber packing, which also deteriorates over time and needs replacing.

The packing can be pretty brittle sometimes, but we got lucky as it came out fairly easily.

With all the pieces completely disassembled, they were headed to the blasting cabinet. Precision Replacement Parts completely restores the frames of the vent windows by sandblasting all the old paint and surface rust away. The parts then get powder coated in a semi-gloss black finish.


Here’s a look at all the parts that make up the complete vent window assembly. Precision provides a brand new piece of glass for the actual window, and even a new lock if you’d like. Of course, all of the seals and packing are new as well. You can also see the nice new powder-coated frames.

The reassembly of the window begins with reinstalling the piece of trim that the lock slides against. Just like the removal, a pair of pliers is used to clamp the piece back in place. A soft towel is used to keep from scratching the new parts.


Using a generous amount of window cleaner as a lubricant, the seal that surrounds the frame is installed.

Starting in the top corner, the seal is worked into the frame with a bone. A lot of attention and patience is needed at this stage of the rebuild as the seals can be a lot of work to get perfect.

After getting the main seal around the outside perimeter tucked in perfectly, the vertical seal goes in. This seal is a little more straightforward and goes in fairly easily. There are locking tabs on this one that will keep it in place once secured. If you decide that you want to tackle this project on your own, these seals (part #VWK 1110 81 A) are also available without doing the vent rebuild program.

The glass part of the assembly is next to get put together. Here is the brand new piece of glass, the freshly powder-coated frame and the rubber packing material used to secure the glass to the frame.


Some pieces of black tape were used to hold the packing in place on the edge of the glass. The packing is wider than it needs to be, but we’ll get to that after we get the frame secured to the glass.

With a couple pieces of padding under the glass, a dead blow hammer is used to hit the frame over the glass, sandwiching the packing between the glass and the frame


A razor blade is used, with light pressure, to trim away the excess packing material after fully seating the glass in the frame.

Now that the glass and new frame are assembled, it is time to join them together. This next step is probably the toughest part if you were to try and do this yourself. The rivet that secures the upper hinge point of the glass to the frame is a specialty piece and requires a specialty tool. The rivet is often called a “smash rivet” and you can see why in these photos. When installed the rivet actually flattens out.


The lower spring and hardware simply go on in the reverse order from which they were removed. The nut secures the spring in place, and the locking tabs on the washer are then bent over the nut to keep it from backing off the stud.

Finishing off the vent window reassembly is the new locking handle mechanism. (part #15617125 for the left or 15617126 for the right) There are a lot of pieces involved in this part as well, starting with the button and seal on the outside of the glass.

After installing the button and seal from the outside, the inside seal is slid over. Attention is paid to the interlocking aspects of these parts.

With both seals installed on the part coming through the glass, the interior pieces are secured to the glass with new hardware.

A couple different springs are used within the handle mechanism. The first one is placed over the mount, and the second one is placed inside the handle itself.

The final step of this complete vent rebuild is securing the handle with the locking pin. Pliers, with some extra protection on the end of the tool, are used to push the locking pin through the handle while the handle is pressed towards the glass and against the spring pressure.

Here’s a look at the completely rebuilt vent window from Precision Replacement Parts. Next they will box it up and send it back to us to get reinstalled in the Blazer.

Flash forward some time and we now have our freshly painted Blazer back from paint and ready to get all the glass installed. James from State 48 Glass Co. came by to give us a hand reinstalling the door glass. He began by sliding the roll-up window back into the regulator

Once the glass was reattached to the regulator and rolling up and down, James installed the new glass run channels (part #GRK 1110 81). These simply slide down into the tracks in the doors and wrap around the top of the door towards the front.

There is a tight corner built into the seal that will be pressed into the vent window assembly once installed. This part of the seal is left hanging for a moment while the new vent window is installed.

Installing the new vent window is obviously easier with the roll-up window in the down position, but it still takes some twisting and angling to get it fit into the door. For cheap insurance, some tape is used on the top edge of the door to protect the fresh paint. Something to pay close attention to when you are reinstalling these vent window assemblies is that the seal is designed to be pressed into the door around the perimeter of the frame.

We opted to pick up some new hardware for securing the vent window back in place.

Now that the completely rebuilt and resealed vent was securely back in place, the felt that wraps around from the back of the door can be pushed into the track on the vent window frame.

The last two pieces needed to complete this job are the belt line moldings. Precision also offers these in a complete four-piece kit that will do the inner and outer of each door (part # WFK 1110 81 A).

Here’s a look at the final result. The freshly rebuilt vent window looks awesome and is sealed up tight. Precision Replacement parts offers every seal imaginable for these trucks, including the windshield gasket (part #WCR 848) and the quarter window gaskets (part # WCR DQ5121) that you can also see in this photo.

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