having my windshield and rear window put in by a local auto glass company. I asked them if they use the butyl tape under the glass on the install [ I think thats what its called and was under glass when i removed it] They say no they are just going to glue it down not sur what type of glue or sealant. they say the butyl tape holds the moisture and cause the rot. my ? is will that be good and will the moldings fit fine or will the glass be to low? another ? i have is do you have to replace the molding clips before the glass is installed I see clips on the side that are installed with screws that i am having troble removing?

Ask them what they are going to do about setting the proper glass depth so that there won't be a big gap between the molding and the glass, particularly the windshield. I've done it both ways, I'll use butyl tape anytime over the urethane crap. That stuff is messy and sucks to work with. Butyl tape is clean and easy and works. I wouldn't worry about the holding moisture aspect.

if they are pros they should know about depth of molding . he told me the molding will be fine. but i am going to make sure thanks for tip

Just because he is a "pro", doesn't necessarily mean he is accustomed to installing glass in classic cars. Its very tricky to get the depth correct with urethane for the moldings to sit just right. The butyl tape can be squashed to fit perfectly.:yes: And as Tom pointed out, that urethane is a mess to work with & usually runs onto your dash. I also don't buy what he says about butyl tape holding moisture.

Bottom line, it's your car not his. I would insist he install the glass with butyl tape, or I would find someone who would. My 2 cents.

Pete

If a guy knows what he is doing the new urethanes are fine. Of course for concours you will want to use the Butyl tape.

I have used both for my cars. The last straw for butyl tape for me was a rear window in my 72 Nova that after several years actually slid downwards in the frame until the bottom edge of the glass rested against the body. I noticed it because the butyl was showing in the interior at the top edge of the glass.

Urethane is MUCH messier to work with, a little more difficult for a backyarder but... is easier to ensure a water tight seal and once it sets its never moving.

You will want to ensure the nail heads (or screws) are in place for the trim PRIOR to having the windshield installed. The molding clips can be installed afterwards.

A "pro" did my 69 and completly F'd it up big time. I made them redo it and it's still not right. Never again, I install my own glass now. I disagree with the fact that it's easier to ensure a watertight seal. I used that crap when I put a new windshield in my 86 Cutlass and it started leaking again right off the bat. I used butyl tape on the Charger and the Cuda, no problems with leakage. The only thing the urethane is good for is putting down a VERY THIN film on the glass channel, using your finger with a latex glove on before laying the glass in that is already fitted with butyl tape.

I have used both for my cars. The last straw for butyl tape for me was a rear window in my 72 Nova that after several years actually slid downwards in the frame until the bottom edge of the glass rested against the body. I noticed it because the butyl was showing in the interior at the top edge of the glass.


Just curious, did you have the spacer blocks in place when the window slid down?

A "pro" did my 69 and completly F'd it up big time. I made them redo it and it's still not right. Never again, I install my own glass now. I disagree with the fact that it's easier to ensure a watertight seal. I used that crap when I put a new windshield in my 86 Cutlass and it started leaking again right off the bat. I used butyl tape on the Charger and the Cuda, no problems with leakage. The only thing the urethane is good for is putting down a VERY THIN film on the glass channel, using your finger with a latex glove on before laying the glass in that is already fitted with butyl tape.

Tom, we are on the same page. I agree with all our you points, including installing my own glass. :thumbsup:

Another thing to keep in mind if you use urethane, if you ever have to pull that piece of glass out, it's next to impossible to do it without breaking it.

Pete

Butyl tape works fine but it's old technology. You won't find many glass shops using it anymore because urethane is so much faster to use. I would give them a sample of the moldings to make sure that they get the glass height correct.

Tom

i prefer the tape, first because i do my own glass install, and i know i could never get the sealer in a tube right-there is a guy near me that can do the butyl. correct, he went to a window competition and that was part of the deal, he went out of his way to show me how its done-i think the tape is more accurate, and managable, as long as you use the correct thickness
maybe look at a couple the guy has done, then you may feel better about his work

The only thing the urethane is good for is putting down a VERY THIN film on the glass channel, using your finger with a latex glove on before laying the glass in that is already fitted with butyl tape.

Tom, after reading many posts about installing windshields and rear glass, I am going to attempt it myself with butyl tape. I see you also lay down some urethane first. Do you still use the pinchweld primer? How much workable time do you have with such a thin film? Does it still have to be wet when you install the glass? I have Pilkington glass and was going with 5/16 tape front and back.

Thanks,
Mike

Going to be trying it myself also.

Tom, after reading many posts about installing windshields and rear glass, I am going to attempt it myself with butyl tape. I see you also lay down some urethane first. Do you still use the pinchweld primer? How much workable time do you have with such a thin film? Does it still have to be wet when you install the glass? I have Pilkington glass and was going with 5/16 tape front and back.

Thanks,
Mike

Mike,

If your windshield is a new one, you will need to use the 3/8" butyl tape. The new aftermarket windshields are thinner than original. 5/16' will still work for the rear glass.

I personally didnt use the urethane to lay down a thin layer. I did use the pinchweld primer & just followed the directions on the bottle.

Hope this helps.

Pete

what is a pinchweld primer????

Pinchweld primer comes in a small bottle with a swab application, you apply a coat of it over your metal flange where the adhesive will go. It serves a couple purposes- it is black in color, adhere's well to a variety of paints/primers and covers any bare metal nicks-provides a clean fresh surface for the butyl to stick to. It is not a requirement with butyl and if your pinchwelds are clean fresh paint you'll be fine without it.

I like urethane for the strength it provides but it sure looks like crap from the inside of the car and butyl can also look bad if not done right. GM used a different product at the factory but butyl works OK.

I am still going through this for my 69 convertible some will only install using the urethane, and not many will still use the butyl tape:sad:
I also cant find a clear windshield for my car either so I have 2 options:
Use my old original one or just get the replacement with the blue tint band:confused:
So I am stuck for now.....:sad:

Brad or anyone else with their original windshield laying around, could you measure the thickness with a caliper, so I can decide what thickness butyl to buy. I have Pilkington windshield which is obviously thicker than the first overseas repro windshield I took back. so I am leaning towards the 5/16 thick tape.

Thanks.
Mike

I removed the glass sanded the window frame and used por 15 around the window frame. Is that good enough to have a glass man come and install my windows. or still use a pinchweld primer?????