The windshield & gasket had been replaced in my 66 when I bought it, & of course, it leaked. I picked up a tube of urethane at Advanced Auto & sealed the glass to the rubber. No more leaks

 

Ops, sorry about that, ole-timers must be setting in??

 

No problem... we all have a little CRS from time to time

I got tired of waiting for a helper, so I did it myself. Picked it up with suction cups on the inside surface, and set it on a shipping blanket on the hood. Then I got in the cab, reached through the opening and lifted it into place. Today is really hot even with a fan blowing... It was a struggle to get the lip over the pinch weld and have it stay. Another thread recommends starting the corners first, and I found that to be good advice. It would have been MUCH easier with someone on the outside to apply inward pressure and "pat" the glass. It still needs to be smacked a few more times, especially in the center, but that's the hardest place to reach even standing on a box.

 

Good work! keep at it. Post some pics.

 

I would - but there's really nothing to see... It's a windshield, a seal, and a truck cab

 

Glad it worked - but I keep seeing in various threads that you shouldn't use urethane because it's much stiffer than the gasket material, so doesn't seal as well as butyl?

 

Agree, Butyl is the best sealant to use. If you have a little drip somewhere Permatex makes some liquid silicone just for that. It's about the consistency of 10W motor oil and will capillary into small openings.

 

I think I'm going to run a bead of butyl all the way around, underneath the seal front lip (where it meets the glass). The passenger side A-pillar doesn't have very much overlap to the glass, but the driver's side is properly seated. It will be hard to "pat" the curved glass sideways that far, so extra sealing there would be prudent. Besides, who's to say it would stay in place, and now I have the driver's side to worry about...

 

I owned a glass shop for 6yrs & urethane was what I always used. They suggest to never use silicone

 

Agree on the silicone. If the area ever has to repainted, it will be near impossible to get it off (to the "paint-clean" level, anyway).

Did your shop change windshields that have gaskets and butyl rubber sealant? I'm sure you know that since around '78(?) windshields have been glued in with urethane, because they are part of the structure. So that needs a stiffer sealant. Before that, they just sat in the gasket, held in by the flap that goes over the pinch weld. Butyl is amazing stuff. It stays flexible, sticky and functional even after decades, on both my '65 truck and my '72 Dart. 3M still sells it for a reason (#8509 Bedding & Glazing Compound).

 

Yes, I’m only talking about sealing a leak, not sealing the entire windshield to the rubber gasket with it. I would spray foaming glass cleaner around the perimeter of the windshield & then use spray air around the inside to find any leaks. I would then use urethane to seal that area

 

Today I did the same R&R on the back glass. That was an adventure. After cutting off the old brittle cracked seal and cleaning off the old butyl from the glass and cab, I put the seal on. It was a better fit than the windshield (also Precision brand).

Then I grabbed a handy piece of polypropylene rope (5/16" maybe), set it in the groove, and applied a fat bead of butyl all the way around. My Harbor Fart suction cup handles worked again - put the glass in the opening (from the inside this time)... and promptly discovered that it wouldn't stay there! So I took it back out, got a length of 2x4, set it in place again and leaned the 2x4 up against it. That was working fine... until it slipped and the glass fell into the cab. Fortunately I'd anticipated this and had a folded shipping blanket on the cab floor.
Except it displaced the seal for a foot and a half. That's really fun to re-seat when it's already got butyl applied. Lucky I have plenty of grease & wax remover.

Tried yet again, this time I could start the seal lip while holding the handles on the outside of the glass. Poly rope was working great until it got to the corners... too tight to pull around and was starting to damage the lip. I removed the rope and worked the seal in, one inch at a time, with a hook tool.

Lessons learned... proper pull-rope diameter is important, also remembering to use a lubricant on it! Most importantly - having another pair of hands really makes this job so much easier.

Here's a pic of the old seal which is very much in need of replacement, and fortunately the headache rack didn't get in the way.

 

Well I'm in southern California, I would hope they beat the snow!

 

I’ll let you know when mine arrives