So I got a new windshield. I was told to gently close doors, avoid carwashing and no getting tint added for a week. I get all that, but I don’t get why he said to go easy on a dirt road. Is it the vibration since they are rarely smooth? Or is it the dust?
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Windshields are bonded to the frame by a strong adhesive which can take time to set fully, hence the precautions. While the adhesive is still “soft”, jarring or vibrations could cause the windshield to move or come loose.
according to the most basic of google searches:
With a new windshield, you should drive extra carefully to help keep it properly in place, especially during the first couple of days. One thing this means is to avoid driving on rough roads. For instance, you should avoid dirt roads and roads that have a lot of bumps or potholes.
If you frequently drive on bumpy roads, try and find alternate routes for the first 48 hours. When you encounter unavoidable speed bumps or potholes, slow to a very low speed before driving over them. Hitting these things with significant force or driving on roads that cause a lot of vibration can interfere with the proper curing of the adhesive sealant.
Takes time to cure/set. Same idea more or less you don’t park on your driveway after its been paved or sealed, things need to set. And during that process dust could get in there, so a bit of both
If the road was sufficiently uneven it could slightly flex the body of the car, to which the windshield is adhered. Sometimes they also tell you not to put the car on a hoist, for the same reason.
Adhesive curing time. The times are also affected by temperature and humidity. The stuff I used was very fast curing, we pumped engine coolant through an iron block that heated our tubes to 180 degrees. A higher environment temperature and lower (higher? I forget) humidity caused it to cure even faster. If it cured too fast like 100 degree temps it could “gas out” where it vented so much air that it created a honeycomb like effect of bubbles in the adhesive. It generally was still okay but not a great look. Average at 70 degrees and 35% humidity was 20 minutes from installation it was safe to drive. 1.5-2 hours and it was totally cured as far as close to full structural strength goes.
The blue tape at the top is to keep the windshield from sliding down in case there are no setting blocks on the bottom or they are ineffective at stopping it.
The funny thing is, you can drive with a windshield after 20 minutes and it is safe in an impact from very rapid sudden force like an airbag or a person trying to eject. However if you sat in the passenger seat you could push the windshield out slowly with your feet still after 30 minutes.
I don’t think dust makes any difference whatsoever. Even if the dust found its’ way to the outside of the adhesive bead, all it could do is attach to the exposed bead which has no effect on the integrity of the installation. What matters is the bond between the existing polyurethane attached to the pinchweld and the bond between the fresh adhesive, and the other side of fresh adhesive bonding to the windshield surface prepared with an activator (helps bond polyurethane to glass).
What? So you don’t get hit with some loose flying gravel and need a new windshield all over again!
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