VCCA Home Forums TECHNICAL - GENERAL Body - Sheet Metal, Paint & Wood 41-48 Master Deluxe Rear Glass Installation

I am proud to say I got my rear window installed. It took weeks of gathering info, clearly understanding what I was up against, and finally gathering the nerve to try. I do believe that glass installation is best when done by one person. I base this opinion on having installed the front windshield and damaging the rubber to the extent that I will redo it, and my success with the back window. Both done alone.

Please remember I am not installing the Special Deluxe stainless surround on my windows because I have a Master Deluxe.

Lets go through some of the steps.

Make sure the inside of the pinch weld is free of old hardened sealer and any sharp edges that might tear into the rubber weatherstrip. You probably will have to remove the tack strip on each side of the window opening. The top tack strip should not be a problem. I hand sanded the pinch weld all the way around the inside.

Glass installation is all about finesse, and finger strength. The rubber can not tolerate any kind of brute strength. Arm strength is just to aggressive. I could apply plenty of pressure on the glass with the suction cups. I didn't need anyone pushing from the inside because this just makes it harder to work the rubber flap over the pinch weld.

Do the installation without the trunk lid installed. You need to stand in the trunk to work on the window. I guess you could try standing on the bumper if your trunk is installed.

You should put a cover on your paint job able to withstand a dropped scraper/screwdriver. I put my first small scratch in my paint job because I didn't have things covered.

Install the rubber windscreen around the glass on your workbench. Put a couple of padded blocks under the glass so the glass is elevated enough to easily work on. You could use soapy water if you lack adequate finger/hand strength to install the glass in the rubber. Center the area where the the rubber is fused together at the bottom of the glass.

The rear window is made of tempered glass so it can not be ground down to fit easier. According to out local automotive glass company the heat from grinding down the glass will make it shatter. So if your new glass is larger than your old one you just have to deal with it. My old glass was about 3/16" larger. Larger glass always means that the rubber is stretched more and makes the installation harder as you work the rubber flap over the pinch weld.

With the glass installed in the rubber, tape the edge of the rubber flap. Use only shinny sided electrical tape that is strong and thick(my tape was to strong to tear by hand it needed to be cut). This is best done by sliding the sticky side of the tape under the flap facing up. Push it all the way to the back of the flap groove and then bend it over the edge of the flap so it ends up protecting about 3/8" of the outside of the flap. This is the critical area that is easily damaged in the installation process. Use shall strips of tape for this, especially on the curved sides. I used only about 1" strips on the curves. Be very careful to press the tape well into place. If the tape on the corners seem to pop up just tape them down. My tape actually stuck so well that it left a residue on the rubber which I took off with GOO Gone.

This is a good time to prefit the window into the the back of the car. You need to see how well you can push the glass into place. Use the suction cups for this. Look for areas that impede a good fit and figure out how you will hold the window in place while doing all the work on the trunk side. I used an ice pick and stuck it in the center bottom garnish screw hole and two drywall nails and pushed them up into the two top middle garnish holes. My drywall nails had ridges in them so they road against the rubber and up through the garnish holes. Don't expect that the window will fit well on each side. The allusion might be that the glass is bowed too much, but it will fit.

It would be easy too just say I will get someone to hold the window in place, but in the end this will lead to frustration and I think a damaged weatherstrip, and a damaged relationship. You could even rest a padded weight against the glass to keep it in place?

With the glass out and back on your workbench now tuck a 1/4" rope under the flap. The rope holds the electrical tape in place and will be used to lift the flap over the pinch weld. It is best to have two lengths of rope both with about 8 inch ends on them. Start the ropes at the bottom middle and end them at the middle of the top. One rope goes left the other goes right. If you are worried about gripping the rope then you are going to be pulling to hard. Always be aware that if you pull the rope at the bottom you may be pulling it down/out from the top. You do not want this to happen because loosing the rope at the top will make it harder to finish the top without damaging the rubber.

Now it is time to lubricate everything. At this point you are choosing to forgo applying sealer. While sealer could be considered a good lubricant it is extremely messy and could cause immense frustration. Sure with a lot of patience it can be easily cleaned up. But dealing with the mess as you install the window could be emotionally toxic. My 41 manual recommends applying it after the window is installed. The lubricant should be chosen with the knowledge that if you ever wanted ever to use a sealant to seal the weatherstrip it might not seal with the rubber (no WD40, linseed oil, grease, etc.).

I used Baby Shampoo for my lubricant, a chemist friend recommends Joy as best. I used it straight from the bottle, no dilution. I applied it all around the inside of my pinch weld making sure I got the right and left sides real well. I also lightly covered the tape on the weatherstrip. I wanted the tape to be slippery but didn't want the soap to start softening the tape edges.

I used my suction cups to mount the window struggling a little to get the ends of the ropes on the outside. I used the ice pick to hold the window in place at the bottom. I secured the top with my drywall nails, with a lot more patience I could have used garnish screws. I released my suction cups and then installed them on the outside of the window.

Because of gravity and comfort it is best to start from the bottom, middle of the weatherstrip. Your goal is to just get the edge of the flap about 1/8" over the pinch weld and work around to the sides. You do this by carefully lifting the rope up which causes the lip to raise up and over the pinch weld. If at any time you are feeling a lot of resistance do not pull hard. Instead use a gasket scraper and pry the rubber flap up in front of the rope, work the rope forward removing the scraper. If you can only go a few inches without having to tug on the rope then just take your time until you can move the rope more easily. Remember your goal is only to get the flap a little over the pinch weld. If the flap slips down behind the rope then re-pry it up with your scraper or a 1" stiff putty knife. If you are right handed begin up the right side. Any time you hit resistance keep prying. Every time you meet resistance apply more lubricant with a 1" brush. Try to keep the entire rubber weatherstrip saturated inside and out to promote easy movement.

As you get closer to the top curve on the right side you want to begin working the bottom flap down. You need to do this to create more space for the top flap. Try using a suction cup to apply downward pressure on the bottom right side. You may have to do this by prying the weatherstrip inside the car, at the left top. Use your scrapper as a small crowbar. Do not concentrate on prying on the right top inside, doing so puts too much binding on the outside left side and might damage the rubber when you try to work it over the pinch weld. Likewise pry the inside right weatherstrip towards the left side where the flap is already over the pinch weld. This prying with continuous application of brushed on lubricant, including from inside the car, will seat the flap and free up additional room to finish the installation.

Taking your time and relying more on your scrapper and finger tips will make it possible to continue over the top and up and down the left side.



These items are must haves... Soap, padded wood block stands for setting the glass onto when mounting the rubber weatherstrip, electrical tape, a gasket scrapper for prying on the rubber, 1/4" rope, suction cups, small container and paint brush for applying the soap lubricant.



How to apply the electrical tape to the flap on the weatherstrip. Small lengths of tape are easier to align than long ones.



Window installed. I did remove the electrical tape as it got in the way. Small suction cups are a must for working alone.



You can see the tape I have left to remove.



The finished job.



The only problem is in the design of the weatherstrip. Where it is joined the seam is imperfect. I noticed this was not going to look right so I cut the groove open more on the inside and sanded in so the groove was not raised under the flap but the overall design flaw still did not settle it down into the right position. Only a VCCA judge would notice the imperfection... I'll use some Goo Gone to cleanup the electrical tape residue.



With all my extra care I still managed a few bruises in my rubber.



I just never had the stomach for using these common tools. I was afraid of damaging the rubber.

Thanks, Mike

Mike, I am impressed with your work and the instructions.

I will strongly encourage you to clean up the description and shorten it and present to the G&D Editor for publication in the G&D.

Someone should present you with an "att-i-boy"

Thanks Ray.
Just an addendum. All the soap can be worked out from under the weatherstrip by just poring small amounts of water under the top and sides of the flap and absorbing the soapy mixture with a towel. As you poor the water lift up on the edge of the flap. The lifting also finishes the alignment of the weatherstrip to the pinch weld. Eventually the soap will be eliminated and after several days the water should have evaporated so you can apply a sealer.

Good luck, Mike

Mike, great job!!!You should be proud and thank you for the time spent documenting the procedure

Hello Mike,
Today I was faced with the same problem. It was to despair. Old Window with Gasket from Cot40s. With three men we have tried it. The only success was that the seal got a small crack. Very annoying. Especially since the price has increased by almost 300% since 2016.
It's hard to get the window, including gasket, inside the recess and you're always too far away from the frame and can't get the lip over it. It also seems to me that the recess in the lip is way too small. But will try your tips next time and report back. Today I have given up.

Reading this thread brought back a memory from my dark and distant past. When I was in grade school in the early '50's, all of us kids went home for lunch. My neighbor had a '46 Chev that he kept on his driveway when at home. The back bumper was right at the edge of the sidewalk when the car was parked in the driveway. One hot day in June as my buddy and I were coming home and passing behind the '46, the rear window exploded like someone had shot it. We both went straight up and then, when we had gathered our wits, started brushing off the little crumbles of glass. Neither of us was cut or hurt - just had a good scare. Naturally I told my mother what had happened. She found my story hard to believe but after talking to the neighbor, deemed what I had said was true. Seems the window had expanded because of the sun striking it, and it had nowhere to expand. I guess GM made them fit to not leak - exploding was another matter!!

Andre asked that I update the pictures in this article to eliminate the problem with Photobucket that you can no longer use without a subscription.

Thanks Mike. But my first Try failed, weatherstrip is distroyed. It was, at no time, possible to get the original glass inside with the rubber.
The outside lip is in my opinion too short and the Rubber to thick between glass and frame. Rubber was from Cot40s years ago, Price 45$ - now 122$. What the …?
Here in Germany you can get the weatherstrip at every corner - NOT!
Rockauto can not deliver at the moment. Will try a universal similar gasket
Which manufacturer did you use? Metro, Filling … ?