3M's respnse to VHB tape for mounting brackets on vehicle?

Gypsy Freedom · Jul 16, 2019

there has been a lot of talk and experimentation with VHB tapes to mount solar panels to the roofs of rigs. i keep hearing a lot of 3rd hand info with a few positive and negative personal results. I my self am skeptical of mounting something on the roof, that is capable of killing someone if it comes off while driving, without a physical mechanical connection.

so i went to the source, i emailed 3M and asked what type of VHB tape ( as they have many different types) i should use to mount a bracket on the roof and how many square inches of tape would be needed to replace two 1/4 inch bolts. i choose this question as i use 2 bolts in each bracket to the roof and then a minimum of 4 brackets on each panel. the answer from them was very clear, they do not recommend replacing bolts with tape in this type of application. i have included the email transcript below if you want the actual words

[font=Arial,]
Thank you for contacting 3M where we Apply Science to Life. We don't suggest VHB or any tapes for those types of applications. Although VHB tapes are strong they wouldn't be able to replace bolts in those applications. We recommend to use the mechanical fasteners provided by the bracket manufacturer.
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Regards,
Roger G.
3M Product Application Support
Industrial Business[/font]
[font=Arial,]- If there is a need to reply to this response, please leave the subject line intact to assure correct routing. -[/font]
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|-----------Original Message Follows------------|

Subject = Products & Services - Consumer

Message = i am wondering if one of your VHB tapes can be used to mount some aluminum brackets to the roof of a vehicle. we normally mount these brackets with a pair of 1/4" threaded through bolts. the primary force will be in sheer due to air resistance while driving but will also have to deal with potential lifting force. but the 2 quarter inch bolts are plenty overkill for a healthy safety margin. would one of the VHB tapes be able to replace these bolts. if so, how many square inches of tape will be needed to replace the 2 bolts. the contact surface on the vehicle will be painted metal or factory gelcoated fiber glass and the bracket is aluminum.

also, what is the anticipated life span when exposed to direct sun (heat cycles) and rain year round. how many years can i expect before needing to replace for safety. will there be visible signs of degridation before failure?

Country = United States

First Name = ********
Last Name = ********

Sender = **********@protonmail.com

referring_url = https://www.3m.com/3M/en_US/company...isitID=29690257421771584165769471615904837294

emailconfirm = **********@protonmail.com

form_key = 1563263613388

resolence_morthy_gread =[/font]

tx2sturgis · Jul 16, 2019

There are many videos on youtube, and reports on the web in various forums, of solar panels that departed from the vehicle roof when mounted with VHB tape. I suppose a large flexible panel mounted with plenty of VHB tape has a decent chance of staying in place, but...if the vehicle is then washed with any type of acidic detergent, (like a truck wash) the likelihood of failure is increased.

I have specifically avoided the use of tape to mount anything structural, and have previously posted some information from the 3M website that supports this.

But it is a good thing to remind those who are looking at VHB as a solution. So, thanks for putting in some effort on this subject.

In my opinion and experience, mounting with bolts/nuts and/or heavy duty self-drilling screws into the roof ribs can be considered a permanent solution.

highdesertranger · Jul 16, 2019

thanks Gypsy for taking the time to do the research. kudos to you. also good for 3M for telling the truth. highdesertranger

poot_traveller · Jul 17, 2019

Roger is just one more person I'm going to prove wrong when I blast down the highway with a solar panel taped to my roof.

highdesertranger · Jul 17, 2019

you do realize that Roger works for 3M, don't you? highdesertranger

poot_traveller · Jul 17, 2019

Yes. And I'm going to prove him wrong.....once I work out how to set up the solar panel.

tx2sturgis · Jul 17, 2019

Why mess around with tape? What you REALLY need is:

GORILLA GLUE!!

Doubleone · Jul 17, 2019

Something to consider about VHB/gluing anything to a vehicle... the bond will only be as strong as the weakest link in the chain. The part will stick only as good as the VHB/glue has purchase onto the paint, the paint has to the primer, and the primer to the metal. In other words, someone could calculate tension and shear forces and translate that into square inches of VHB, Gorilla Glue, 3M weatherstrip adhesive (my personal favorite), or even the strongest glue ever invented (space shuttle perhaps?), but wind buffeting and such could fracture the paint right at the margin and pull the paint off the top of the van along with an expensive solar panel. I'd suggest to stay with a drip rail style mounting system (easiest and no holes in the roof), or attach brackets through the roof at the cross beams or edges using stainless bolts or blind rivets. The advantage of bolts is that you can leave them a bit slack so the roof doesn't tweak or dimple and create a place for water to pool. I'd use some VHB, Dicor, or other sealant between the bracket and roof for weatherization. BTW, we've used 1/4" stainless bolts on the wings of 200+mph race cars, so a good 1/4" bolt is plenty strong at freeway speeds.

Gypsy Freedom · Jul 17, 2019

poot_traveller said:
Yes. And I'm going to prove him wrong.....once I work out how to set up the solar panel.

even if your panels stay on in your test. that does not prove it is a safe or even reasonable application.

i just hope if during your test or in the years to come, the panels come off, there are no innocent people behind you to take a panel through the windshield. i could never live with myself if i killed someone due to "trying to prove the manufacturer wrong"

RoadStar66 · Jul 17, 2019

To address your concerns that a panel could come loose and hit a trailing vehicle, drill a hole or two into the more substantial part of the solar panel and attach a steel cable by some secure method. Attach the other end to a substantial part of your vehicle. Then, if the panel comes off, it may dent and scratch your vehicle, but it won't go sailing as a lethal missile into the windshield of a following vehicle.

For attaching the panel, maybe a multiple element adhesion approach is best. VHB + neodymium magnets. The magnets might give supporting adhesion that would bolster the VHB's. Regular inspection of the panels' condition should be done. But the backup tether is essential for safety's sake.

We also have to consider that any accidents involving panels coming off will slime the entire nomadic community. Another justification in some of the publics' eye to rein in all these "homeless" by any other name people in vans and cheap RVs.

Gypsy Freedom · Jul 17, 2019

no, i have no "concerns" i agree with the 3M rep, it is not a recommend use. i have no desire to try and prove them wrong when the lives of the people behind me are at stake

a "tether" would have to be quite strong, just think about it. there are already 2 x 12- 10 gauge cables that would be acting like a tether. on the cases where folks have reported losing a panel i have never hear someone say they heard a load noise and then pulled over to find their panels flopping along side. no they are just GONE, ripping the cable. have you tried to break those cables, we are not talking weak stuff

tethers are a great idea for security when you are already doing it the right way and just want a little back up. like safety chains on trailers. the hitch is designed and recommended for that purpose. the chains are just in case.

there are plenty of other threads you can go chime in on how to not follow the manufacturers recommendation

maybe a mod could close this thread before it turns into a jumble of differing opinions that hide the intent of the post

poot_traveller · Jul 17, 2019

Gypsy Freedom said:
even if your panels stay on in your test. that does not prove it is a safe or even reasonable application.

i just hope if during your test or in the years to come, the panels come off, there are no innocent people behind you to take a panel through the windshield. i could never live with myself if i killed someone due to "trying to prove the manufacturer wrong"

My test trials will also involve finding out how much pressure is required to force the VHB tape to fail - And I will make it fail.

If I come back with strong evidence that VHB tape will easily hold a solar panel to the roof using four Z brackets for the mounting surface area, then what are you going to say?

poot_traveller · Jul 17, 2019

RoadStar66 said:
To address your concerns that a panel could come loose and hit a trailing vehicle, drill a hole or two into the more substantial part of the solar panel and attach a steel cable by some secure method. Attach the other end to a substantial part of your vehicle. Then, if the panel comes off, it may dent and scratch your vehicle, but it won't go sailing as a lethal missile into the windshield of a following vehicle.

For attaching the panel, maybe a multiple element adhesion approach is best. VHB + neodymium magnets. The magnets might give supporting adhesion that would bolster the VHB's. Regular inspection of the panels' condition should be done. But the backup tether is essential for safety's sake.

We also have to consider that any accidents involving panels coming off will slime the entire nomadic community. Another justification in some of the publics' eye to rein in all these "homeless" by any other name people in vans and cheap RVs.

I understand your concerns but in my opinion if the average person found out you're using a tether line just in case your solar panel becomes detached from it's mounts, the first thing people will think is; "May be he should use something stronger to hold the solar panel on if he isn't confident his mounts will hold."

poot_traveller · Jul 17, 2019

Gypsy Freedom said:
on the cases where folks have reported losing a panel i have never hear someone say they heard a load noise and then pulled over to find their panels flopping along side. no they are just GONE, ripping the cable.

And probably ripping free of the tether line as well.

Have you ever come across cases of people saying their solar panel became detached from it's mounts and the panel was flopping along side the van held on by the tether line? Probably not. Tether lines only give a false sense of security.

In my opinion; do it once, do it right....and that starts and ends with making sure the mounts stay attached to the roof.

Gypsy Freedom · Jul 17, 2019

poot_traveller said:
My test trials will also involve finding out how much pressure is required to force the VHB tape to fail - And I will make it fail.

If I come back with strong evidence that VHB tape will easily hold a solar panel to the roof using four Z brackets for the mounting surface area, then what are you going to say?

i will say your 1 short term test means nothing, and does nothing to disprove the manufactures recommendation in a life and death situation.

poot_traveller · Jul 17, 2019

Gypsy Freedom said:
i will say your 1 short term test means nothing, and does nothing to disprove the manufactures recommendation in a life and death situation.

How could it mean nothing?, So if I need massive amounts of force to make the AHB tape fail, that means nothing?, and does nothing to disprove Roger's butt covering claims?

Gypsy Freedom · Jul 17, 2019

exactly, one test proves nothing. we already have many reports of the product failing. your 1 test can not even come close to emulating a life time of being up on the roof in the sun and rain and gawd only knows what chemicals in might get exposed to from the rain or washing.

manufactures and engineers go through millions of dollars in testing on products to determine safe working applications. your jerry rigged tests dont even compare to the testing that has already been done. the fact that you think different is scary.

sure YOU might get away with it this time, but that doesnt me you will get away with it all the time.

i am done, you will get no more response from me

poot_traveller · Jul 17, 2019

Gypsy Freedom said:
exactly, one test proves nothing. we already have many reports of the product failing.

People claim the tape failed but they leave out the part that they didn't put it on correctly, or they didn't use rubbing alcohol mixed with water to clean the area, or they put it on an old paint job and the paint detached, but they leave all that out when they claim AHB tape "failed".

poot_traveller · Jul 17, 2019

Gypsy Freedom said:
your 1 test can not even come close to emulating a life time of being up on the roof in the sun and rain and gawd only knows what chemicals in might get exposed to from the rain or washing.

I see the problem, you haven't done your research on 3M AHB tape. It is 100% unaffected by the sun, rain, high temperatures, extremely low temperatures and anything else you can throw at it for years and years on end.

geogentry · Jul 17, 2019

poot_traveller said:
I see the problem, you haven't done your research on 3M AHB tape. It is 100% unaffected by the sun, rain, high temperatures, extremely low temperatures and anything else you can throw at it for years and years on end.

Haven't the people at 3M done far more extensive testing and research than your are capable of doing? Their conclusion was not to do it.

I await your white paper with the conclusions of your trials which I am sure will contain all necessary environmental data, equipment used before, during, and after which was used to record such data. And any pertinent factors to provide proof that you are better equipped to test the product versus the manufacturer.

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3M's respnse to VHB tape for mounting brackets on vehicle?

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