Windshield fragility?

[hitman912]

Hi all,

Got my car registered and on the road a few weeks ago. We went to our first little show on 10/28 and everything was fine when cleaning the window beforehand and we didn't notice any issues when we got home.


On 10/29 though, we went out to the garage and the windshield had a 12 inch crack going from the top near the frame down to the middle of the window. 11/2, without having driven since, the crack has gotten larger.


I'm not a glass expert, but should that happen? A crack starting under the top of the window frame without hearing a rock or seeing a chip and then having it grow without leaving a 50-70 degree garage? Or are there defects with the ffr glass or frame?


I'd like to know before I buy another windshield from them only to have it happen again after 120 miles. I'd probably get the acrylic from somewhere else if it's a known issue.

Thanks

[egchewy79]

Are your sun visor screws going directly into the frame?

[hitman912]

No, I don't have visors on and the crack is not near the mounting points.

[Alan_C]

Something is putting stress on the glass. The glass will last if it is unstressed as I found out personally after having two windshields break both just sitting in the garage overnight after a outing. On the third windshield I followed Jeff Kleiners advice and made shims for the post where they bolt to the frame. If you don't shim the gaps, the bolts pull the rails to fit and stress the frame around the windshield. This is the first step to take before a final install of a new windshield is attempted. Did it work, I think so as the 3rd windshield installed has lasted more that 5 years and 13K miles with most of the miles by the second owner.
Also, as posted, screw length has to be very precise when installing the accessories. I installed both the visors and wind wings without issue. Some of the screws were ground to reduce length and remove any edge that could contact the glass. Your crack is in a different place and larger than what I dealt with. My windshield cracks were always in DS lower corner about 8 to 10 inches long.
Sorry to hear you lost your windshield. IMO FFR could do a supplement on proper installation and include it in the kit. The cracking problem has bit a lot of owners. If not a installation supplement, maybe a sticky with Jeff's advice and what others have determined could be an alternative.

[Jeff Kleiner]

Thanks Alan, you just saved me from having to do a bunch of typing to repeat this for about the twentieth time!


Something is putting stress on the glass. The glass will last if it is unstressed as I found out personally after having two windshields break both just sitting in the garage overnight after a outing. On the third windshield I followed Jeff Kleiners advice and made shims for the post where they bolt to the frame. If you don't shim the gaps, the bolts pull the rails to fit and stress the frame around the windshield. This is the first step to take before a final install of a new windshield is attempted...

Hitman, yes---you must shim between the chassis and the windshield arms to take up any gaps (usually about 3/16"-1/4" split between the two sides) before tightening the attachment bolts. If this isn't done the glass is under stress and will "spontaneously" crack. It must remain fully relaxed.

Jeff

[Railroad]

I shimmed the passenger side and spent a lot of time with the job. When I got my car back from painting, no shims. I am sweating bullets, but so far no crack. 2000 miles and nearly a year.

[JohnK]

My windshield posts were both twisted as well as angled outward. Shims alone will address the gap between the posts and the chassis but not the twist. The posts are soft chrome-plated brass so I "massaged" them with a large crescent wrench and got them perfectly plumb and square. My install was slightly different as I was installing my windshield using quick release brackets so aligning the posts was necessary to get them to slip into the brackets properly, but the same straightening process would work just as well with a "normal" windshield install, eliminating the need for shims.

[chmhasy]

When the windshield is manufactured they don't size(sand down) the edges to remove the micro-fractures. This is the main reason why the windshield cracks. the stress on the glass just adds to it. you need to get the windshield out of the frame and bring it to a local windshield shop to size (sand down) the edges to remove the micro-fractures. In this picture you can see the micro-fractures before I sent it out to be sized.
191868

[Alan_C]

I shimmed the passenger side and spent a lot of time with the job. When I got my car back from painting, no shims. I am sweating bullets, but so far no crack. 2000 miles and nearly a year.

Sorry to say, if you needed shims before, they are still needed. You are on borrowed time, shims are inexpensive compared to a new windshield. Do it sooner rather than later as you think you are fine until the crack appears.

[Peeker]

Try the Lexan windshield that 520speedworks sells. They do not crack. I am very happy with mine.

[Jeff Kleiner]

Sorry to say, if you needed shims before, they are still needed. You are on borrowed time, shims are inexpensive compared to a new windshield. Do it sooner rather than later as you think you are fine until the crack appears.

191870

Jeff

[Norm B]

I have been on the road 10 years now. The windshield is much more robust than I expected. It has rock chips and other damage but no cracks. Car has been driven over some really rough roads and I even got airborne once after going over a Texas gate that I missed the warning signs for. Only thing that got damage from that was my hearing when my wife let go the bad language at me.
I very carefully followed Jeff’s advice on shimming the windshield frames during installation. Made sure the body cutouts were big enough to prevent contact and putting pressure on the frames. Used none hardening silicone to seal the openings and took the windshield out of the frame to install the visors. Had to trim the visor screws about 1/16 because they protruded through the frame. While I had the windshield out, I noticed the edge was very rough. Looked like it had been cut to size by a rabid beaver. Wet sanded the edge in steps up to 2000 grit to get a smooth edge. Don’t know if it was all this prep or just luck that it has lasted this long.

Norm

[Railroad]

Sorry to say, if you needed shims before, they are still needed. You are on borrowed time, shims are inexpensive compared to a new windshield. Do it sooner rather than later as you think you are fine until the crack appears.

I would love to have the shims back in place and have some of the shim material left, but it looks like they bent the leg, like a dog leg bend, and bolted to the frame.
The painter has two assistants in the shop. I am guessing they did not bother to find the shims, or everyday is a blank.
Not happy, but very hesitant to start wrestling with it.

[Alan_C]

McMaster Carr sells shims in various thicknesses. When I made up my stacks I used a feeler gauge to determine each gag, I put a little RTV between the required layers to hold them together. I get it is a pain to get back in there and finish it up right, but you will likely be dollars ahead doing so.
https://www.mcmaster.com/products/shims/slotted-shims-7/

[egchewy79]

you can also use body mount shims. I bought a whole 200 piece kit on amazon for like $10