We have never broken one during removal or install. We were very nervous about removing and reinstalling the windshield with the crack so we were super careful (and had a fair amount of experience on our side at that point.) In the beginning, we were super careful because we weren't sure we could find a replacement. Then we had some solid experience, and had developed a removal method once we found that we could source replacements.
I have broken a windshield out of the car... On our shop move a few years ago, I didn't pack one well enough...
And, who says it doesn't get cold in Arizona? Why I've seen temps in the mid-to-upper 30's!! - well, until the sun comes up... (and I'm wearing a light jacket while these Arizonan's are bundled up in ski parkas - I grew up in Idaho and waited for the school bus in -30 temps.)
Okay, I'll admit that we don't trust any modern windshield installers. They glue windshields in. That's pretty much all they know. A gasketed windshield installed over a flange is foreign to them. So, here's how we don't crack windshields:
A. Use a utility knife (Xacto knife, single edge razor blade) to slice away the thin rubber that holds the trim on. Remove the stainless steel trim.
2. Utility knife - slice the exterior gasket carefully in the flat that was covered by the trim. You're looking for the edge of the glass. Once you find it, cut around it - all the way - enough that you can remove all the rubber from the outside face of the glass.
2b. You can do the above by yourself, but what follows really needs an assistant. Or two.
c. Carefully push the glass out from inside the car. Lift just a little bit all along the perimeter until you're sure that all edges of the glass are unattached and it can be removed without interference.
D. Remove the rest of the original gasket from the flange and clean the flange completely. REMOVE the dash finisher (the black crescent moon shape metal piece).
5. Get the new or exisiting windshield on a stand and install the new gasket on the glass. Be sure the glass is fully in the channel all around. Lube helps - very soapy water.
6. Install the stainless steel trim - not the corners, just the long pieces. Ya, do it now - it's MUCH easier than after the windshield is in place. The back side of the trim IS SHARP. It'll slice the rubber if you're not careful. You can file or sand the sharp edges if you're OCD (or even if you're not...) You have to raise the rubber flap up and over the edge of the trim. Lube helps - we use Meguiar's Hyper Dressing - and a smooth skinny tool: Awl, pick, screwdriver, smooth without sharp anything that will cut the thin flaps that hold the trim.
g. Install a long cord in the gasket groove - thicker is better - like the olde tyme clothes line cord, cotton is better, but I have 3/8" polyester that works. WET the cord FIRST - yup, soak it in water. Add a little dish soap if you want, we need lubrication. The cord needs to pass each other at the meeting point by 10-12 inches. We like the meeting point at the top of the glass in the middle and the ends need to hang out fairly far - you need to get a good grip on either one - perhaps wrapping it around your hand.
H. Lube up the windshield flange metal with some dish soap and water or Hyper Dressing.
i. Two people - set the windshield - with the gasket snug all around - into the flange. Cord ends should be inside the car. Make sure it's centered all around.
ii. One person is going to pull the cords inside to pull the rubber gasket into the interior of the car, sealing it to the interior side of the flange. At the top and on the pillars it'll be set over the vinyl. The other person is going to be on the outside holding the glass in place while the cord is being pulled. That person will use both hands as often as possible, palms down, fingers splayed on the glass. Their job is two-fold: 1. As the cord is pulled, the glass will want to move opposite of the pull (starts at the top, it'll want to move down, when the pull is on a side, it'll want to push to the other side. Exterior person needs to keep the edges of the glass/gasket from moving out of the hole the windshield sits in. 2. When the cord is pulled the glass needs to sink into the frame when the rubber is pulled into the interior. So, a certain amount of exterior pressure can be needed to keep the glass settling inward as the cord pull progresses.
J. With the person with hands on the glass externally, the person inside starts to pull the cord. The cord hanging on the right side will be pulled to the left, and vice versa. Pull one cord only. Pull it at a 90 degree angle to the glass. Pull carefully and slowly if necessary. Don't pull so fast that the person on the exterior can't manage keeping the glass in place or help you get the glass to sink into the hole. I'll be easy until you get to the top corner(s). Stop at the corner and pull the gasket up on the inside and get it set into the flange as much as possible. The gasket needs to be pulled outward (like lifting it the same direction as the outside edge of the glass) getting it to set firmly in the flange. That helps the glass pull inward as well. At the corner, go very slowly and swing the cord in a circle as you're carefully pulling corner gasket rubber. Sounds stupid, but it works and doesn't cut the gasket. Once past, make sure your helper keeps the glass from moving out of the hole on the opposite side. Before getting to the bottom corner, pull the gasket into the flange - do it as you go and it'll help. Now pull across the bottom - it'll want to make the glass pop out of the side that's not pulled yet. All this time your helper needs to be getting the windshield to push inward as you're pulling cord and setting gasket into flange. If you have two helpers, it makes it very easy. Keep going around the entire windshield and do the second top corner same as the first. Pressure on the outside. Finish up by pressing firmly down on the outside, and pulling the gasket firmly into the flange on the inside.
k. if it doesn't set right - have no fear - just remove it and start again. Pull the gasket rubber on the inside down on one corner and push that corner out carefully - continue around the whole windshield, take a deep breath, lube it up, try again. (But... It's a LOT easier if you're patient and get it right the first time...)
L. Push the gasket out as far as you can - especially at the top corners. Install the trim corners and gap cover pieces. The stainless steel trim is not just for looks - it helps maintain the gasket in it's proper place and will help stop the gasket from pulling away from the top corners. Don't use it at you own peril...
Note: I do not use any adhesive or gasket seal. These gaskets were designed to seal around the glass and flange without it. Now, I'm fully aware that that isn't always true. BUT, Arizona (no rain) and Z owners here wouldn't (don't) drive their Z's in the rain even if there was. Okay, they still wash their cars, but heat and NO humidity dries things FAST here. YOU can decide for yourself if you want to use such a thing - Nissan did - in spots - on the later models. I still don't.
And: Patience is the key to Joy... Fortune cookie...