by Bob Beranek
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High modulus urethane (HMU) can be confusing if you do not know all the specifics concerning its use. I remember when HMU first came out. I wanted to get the facts, so I called urethane manufacturers and vehicle manufacturers and asked for a definition of “high modulus.” Most of the answers I received were the same: “it is higher in modulus than normal urethane.”

I’m glad we got that cleared up, but what does a vehicle with an original equipment windshield installed with HMU mean to the technician in the field? Do you have to replace the windshield using HMU?

HMU is stiffer and has less elongation than normally cured urethane. While the shore harness of normal urethane is 50 to 60, HMU has a level of 60 to 70. As far as elongation, a normal urethane may have as much as 400-percent elongation while a HMU may only have 250 percent. According to vehicle manufacturers, HMU is used to stiffen the body for performance reasons. HMU, in conjunction with other stiffly bonded or welded panels, makes the vehicle less flexible than a normal unibody constructed vehicle, thus making a vehicle’s handling more precise and firm.

So is high modulus urethane a safety device? Does the customer have the right to waive its use? Some vehicle manufacturers contend that HMU is a feature built into the automobile for performance only, not protection of the occupants. Engineers and crash re-constructionists might not agree completely with that statement.

Does HMU boost performance? Yes. However, the argument on the safety side is that when a vehicle body is modified from original design, such as when a windshield installed with HMU at the factory is replaced with normal urethane, the crash dynamics change. In this case other panels and components may not act as predicted. If any of the other panels are structurally designed for safety crush zones, and counts on the rigidity of the HMU bonded windshield, then the safety would be compromised.

I have the tendency to avoid playing with what works. For the safety of my customers I will replace the glass in the same way the engineers designed it. If an installation calls for HMU or non-conductive urethane, I will replace it with HMU or non-conductive. As a trainer, I always try to find the reasons why a certain process or product is used. However, sometimes it is better to replicate the OE method rather than try to outthink the engineers.

I invite any and all urethane chemists out there to comment on this post. I would love to hear your layman’s explanation for the use of HMU and whether it makes a difference in the vehicles’ safety cage.

Rarely are we able to witness firsthand the fruit of our labor. Auto glass installations are usually not measured as safe until something terrible happens. Here is a story behind a picture.

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Adam Kox had a broken windshield and asked my son, Jay Beranek, if he would replace it. Upon pre-inspection, Jay noticed that there was corrosion showing itself from behind the molding and mentioned to Adam that body work was necessary to restore the vehicle to a safe condition. Adam works in a body shop so he had Jay take out the glass and he and his fellow technicians replaced the metal per Jay’s instructions. Once the metal was replaced and properly painted, Jay installed the new windshield.

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Six months after the installation, on a winter afternoon, Adam was driving down a highway. When changing lanes, his tires hit a slippery spot and his vehicle left the roadway. His Honda Civic rolled an estimated four times and came to rest. The vehicle was old enough not to have the safety of airbags and was only equipped with seatbelts.

Adam was knocked out and lost consciousness. Adam was able to leave the vehicle and assess the situation. Remembering the conversations he had with Jay about the importance of a properly installed windshield, Adam’s first thought was, “that windshield saved my life.”

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In my 30-plus years of installation, I have never had the satisfaction of witnessing the substantiation of my installation efforts, but here is proof that good installations spur good results. I wish to thank Adam for coming forward and telling me his story. More importantly, I want to thank Jay for listening to me once in a while and practicing safety auto glass glazing.

Re-initialization is a big word with big safety implications. Re-initialization is the resetting of the anti-pinch features of the automatic closing of an opening. This opening can include doors, sunroof panels, back glasses and door glasses closed by automatic means. The anti-pinch feature, built into the mechanism, is an automatic reverse that would free an individual’s head or limb caught between the panel and the frame of the vehicle. If the auto reverse doesn’t work properly, serious injury or death can occur.

The federal government in November of 2004 amended the Federal Motor Vehicle Safety Standard 118—Power-Operated Window, Partition, and Roof Panel Systems to include a new paragraph (S6) defining the regulation of “accidental actuation test.” This test basically states that windows that have automatic closing features must include the anti-pinch reverse.

How do we know if it has an automatic reverse? If it has an “auto up” feature, it has an anti-pinch reverse built in.

How do we know if it has to be reset? If you depress the control switch using the automatic feature, it will travel to the closed position but it will not stay closed. It will reverse. If you try it again, it will reverse again. This is an indication that a re-initialization is required.

Can we avoid having to reset the anti-pinch feature? That depends on what happens with the regulator between the times the glass breaks and when it is replaced. If the regulator movement exceeds the normal distance of travel during that time, then the reset is required. If the regulator remains within the range of travel, then it may not need re-initialization.

How do we reset the anti-pinch? Now that is the million dollar question. Over the last eight to ten years, the requirements to reset moveable glass have been all over the board. The procedures for some manufacturers have been quite time consuming while others take less than a minute.

There is some good news. Although Volvo still requires dealer involvement on most of their models, re-initializations on today’s vehicles are becoming simplified and most can be done in the field without dealer involvement. However, there are a lot of time-consuming re-initializations out there and we need to know how to complete them safely.

So do we know how to complete a re-initialization? The truth is that reset procedures are not easily obtained. I had to collect mine from manufacturers’ sites that charge for the privilege. It took me a considerable amount of time to wade through the automotive jargon and the pages of service manuals to find the location of the instructions. This is, however, something we must do to meet the FMVSS 118.

I am working to compile a complete list of re-initializations procedures. Until then, here are some basic instructions that will work on approximately 10 to 15 percent of the vehicles we see today.

1. If the door window fails to stop in the closed position and reverses down 4 to 6 inches, it means that the regulator must be re-initialized.

2. Once the glass is installed, re-attach the window control connectors to the window switch console.

3. Depress and hold the window switch to the down position until the window has reached its fully open position.

4. Continue to hold the down switch for 4 to 6 seconds after the window has reached full opening position.

5. Pull-up or depress and hold the window control switch to the closed position until the window travels to the fully closed position and the window is seated into the upper frame weather strip.

6. Continue to hold the switch for 4 to 6 seconds after the window is fully seated.

7. Then depress and release the “auto down” (open) switch and observe the window’s movement. It should open and stop.

8. Then depress and release the “auto up” (close) switch. It should travel and seat into the upper weather strip and stop without reversing.

9. Repeat several times using the automatic feature to confirm operation.

10. Lower the door window. Use a rubber mallet or piece of wood and place between the upper window edge and the upper door frame. Depress the “auto up” switch and observe window movement. It should make contact with the obstruction and reverse. If not, re-initialization must be repeated or the vehicle must be taken to the dealer for re-calibration.

If all of the resets were this easy, we would be very happy.