Why we tell people to NOT use magmounts

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I've currently got a small mag mount (Diamond MR73S) on the roof of my Impala at the moment. I put it on there yesterday and tonight (Now that the weather is nicer...) I will be popping the holes for the four NMO mounts that will go on the trunk lid. The weather's not been cooperative and I don't have an enclosed bay to work in...
 

03msc

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I've currently got a small mag mount (Diamond MR73S) on the roof of my Impala at the moment. I put it on there yesterday and tonight (Now that the weather is nicer...) I will be popping the holes for the four NMO mounts that will go on the trunk lid. The weather's not been cooperative and I don't have an enclosed bay to work in...

Temporary is OK...it's those that run them permanently that the thread is about.
 

W9WSS

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I currently have 12 NMO mounts on my vehicle. Matter of fact, I have a few people who wish to buy my car in its present condition, most likely with all the current radios installed. Not sure about that yet, it could be an option. I did that once before, everything including all radios with no regrets.

I go through "touchless" automatic car washes with no problem. Even the final bar with stringy cloths at the end cause no problem. If you'll notice most of the antennas have springs (the EM-WAVE springs are built-in under the rubber protectant). I avoid the automatic car washes with brushes unless I remove each and every antenna, and put caps over the NMO mounts. I used to do that when I had 4-5 antennas, but since I have 12 now I use the touchless washes, and at rare times, wash by hand.IMG_1882.jpg
 

W9WSS

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Matt, here ya go. The empty mount on the middle left side was the former holder of my iPhone 7; I have since upgraded to an iPhone XR128 which required a wider mount. It looks about the same but has clamping grips on the side
 

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W9WSS

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I also have two VRS750 P25 cross-band repeaters in the trunk. They are interfaced with the UHF & VHF Astro Spectras. When activated, I can use my XTS portable radios remotely that use the high-power radios for extended range and output. There's a Kenwood TM-D700 at the top, Yaesu FT-857D, Code 3 Light/Siren/PA control (disabled), Motorola UHF Astro Spectra, Uniden BCD996T, Motorola XPR4550 VHF DMR Radio, Motorola XPR4550 DMR UHF Radio, two cup holders at the bottom (not visible). On the right side of the console is the control head for the Motorola VHF Astro Spectra, and on the top left of the side of the console is the Alinco DR-235 222 MHz transceiver probably not visible. Everything is controlled by relays that activate when the accessory/ignition is turned on. When everything is off, measured draw on the battery is about 9 milliamps. Everything was installed and is maintained by certified mechanics and experienced installers. I'm too old to get under and next to the dashboard, trunk, or hood. My health doesn't allow it anymore although that's what I used to do!
 

78k10

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I’ll add my 2 cents here. I don’t have an NMO on my truck- yet. When I put the scanner in a while back, I ordered a magnetic NMO mount from amazon. The first one didn’t show up, so I ordered another one. Well, it made it almost here and then I got an email saying there was a problem and it would be returned. I ended up ordering a universal hood channel bracket and now I’m glad the magnet mount never showed up. I’m much happier with the permanent mount on the hood. I would have run the coax down the back glass, and under the truck into a grommet for a permanent install. But knowing me, that coax being visible would drive me nuts. And knowing that there was water under the magnet after every storm would eat at me. I am now considering drilling the roof to get the antenna higher. However I know that if I put it up top it will be through a hole.
 

mmckenna

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However I know that if I put it up top it will be through a hole.

If you are happy with the hood channel mount, you'll love a permanent mount. Having antennas down below cab level isn't doing you any favors. It also stands out a lot more. Put it dead center on the roof and the thin whips tend to disappear.

Don't put it off too long….
 

78k10

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I’ll also add that I’ve noticed a lot of vehicle manufacturers have began using roof mount antennas, so they can be done effectively without worrying about leaks.

On a side note, wouldn’t twelve 3/4” holes in the roof begin to undermine the roof’s structural integrity in the event of an accident/rollover? Not trying to be critical, just curious.
 

rescue161

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The structural component of the roof is more a job of the pillars and the cross members under the extremely thin sheet metal. The NMO has been around d for 50 plus years. They fine-tuned the leak thing a long time ago. None of the NMO mounts that I've installed have ever leaked.
 

rescue161

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Unless you are going out every time it stops raining and wiping off the water that gets trapped under the magnet, there is going to be damage. You may not see it at first, but it is occurring, slowly and steadily. The attached pictures are of a de-install of a police car that had a license plate reader system (LSAG). This particular LSAG used three magnets coupled with lip mounts. The three magnets ensured that it did not lift up on the far end of the lip mount and the lip mount kept everything stationary. It was a rock-solid mount that worked great and did not move, but after three short years (that's how long we usually keep the cars in service), you can see the damage. Rust, scratches and paint fade are very noticeable in these pictures. I have another one of an airfield truck that had a magnetic mount light. It had severe damage that had to be repaired before GSA would allow us to turn it in.
 

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Ensnared

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Unless you are going out every time it stops raining and wiping off the water that gets trapped under the magnet, there is going to be damage. You may not see it at first, but it is occurring, slowly and steadily. The attached pictures are of a de-install of a police car that had a license plate reader system (LSAG). This particular LSAG used three magnets coupled with lip mounts. The three magnets ensured that it did not lift up on the far end of the lip mount and the lip mount kept everything stationary. It was a rock-solid mount that worked great and did not move, but after three short years (that's how long we usually keep the cars in service), you can see the damage. Rust, scratches and paint fade are very noticeable in these pictures. I have another one of an airfield truck that had a magnetic mount light. It had severe damage that had to be repaired before GSA would allow us to turn it in.

I have owned many magnetic mounts, including the K40 which has to be pried off with a crow bar; however, if you notice, my magnetic mounts have rubber boots on the bottom. If the scratches are present, you might need a magnifying glass to see them. I thought people could see my photograph and see the rubber boots, but you have to look hard, LOL. This is the only reason I use Tram bottoms. Thank you for your response.
 

rescue161

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It has nothing to do with rubber boots. Would you walk on your car's paint with dirt on your feet? How about socked feet or even rubber boots? Now, just imagine those same boots or socks with sand or dirt stuck to them; would you still walk on your car? The LSAG cameras had those same rubber boots on the magnets. It has everything to do with trapping dirt and water between that rubber boot and the body of the vehicle. People have tried everything from pantyhose to rubber boots. If you leave anything in contact with the body of the vehicle for extended periods, there will be damage. Like I said earlier, I don't really care either way as I don't use magnets on my personal cars. I'm just presenting facts from my experience as an installer.
 

03msc

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@rescue161 Some people just don't get it...they think the rubber somehow helps, not realizing it allows more to get trapped under there. Some will argue with and deny the evidence showing they're wrong. This thread is testimony enough as to why mag mounts are bad. Why people are so bull headed is beyond me...

Mount them right...or at least don't try to justify improper mounts by saying the evidence is wrong.
 

78k10

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I guess I should say that I also have mag mount antennas. I have a cb antenna that is only used every now and then, and is removed when not use. I also have a cheap mag mount scanner antenna on my beater car. It’s been in several months, but I should say that it came to me with a maaco paint job and cracking body filler already, so a little paint damage on the roof isn’t an issue here.
 

Ensnared

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It has nothing to do with rubber boots. Would you walk on your car's paint with dirt on your feet? How about socked feet or even rubber boots? Now, just imagine those same boots or socks with sand or dirt stuck to them; would you still walk on your car? The LSAG cameras had those same rubber boots on the magnets. It has everything to do with trapping dirt and water between that rubber boot and the body of the vehicle. People have tried everything from pantyhose to rubber boots. If you leave anything in contact with the body of the vehicle for extended periods, there will be damage. Like I said earlier, I don't really care either way as I don't use magnets on my personal cars. I'm just presenting facts from my experience as an installer.

I still remain unconvinced. Of course, this is my belief and opinion. I can observe the paint. I asked a paint specialist to look and see if there was any significant damage when a more pronounced car-scratcher connected with my car, a deer. If my wife is happy with the leftovers, then I am a happier man. I have used lip mounts and they do damage as well. To each his own. For me, I am happy with my boots.
 
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