NMO mount

va3wxm · Post by **va3wxm** » Thu Oct 06, 2005 11:04 am

What is the maximum thickness of metal a standard NMO mount can be used with? 1/32"? 1/16"?

I'm looking to put one on the trunk lid of my car and the ideal spot (in the center) has the outer sheet metal sandwiched with some kind of inner sheet metal ribbing. It doesn't look that thick but I want to be sure before drilling the hole.

g0dl355 · Post by **g0dl355** » Thu Oct 06, 2005 11:38 am

I tried to mount one like that in a 2000 or so Crown Victoria.
The metal was too thick to go through both skins, so I mounted it near the glass where there is a hole in the second skin that allowed me to screw it down tightly.

What car are you mounting this in?

crazyboy · Post by **crazyboy** » Thu Oct 06, 2005 12:15 pm

How aobut one of those extra deep NMO mounts?

apco25 · Post by **apco25** » Thu Oct 06, 2005 12:19 pm

Or install as you would for a double roof. Drill a pilot hole, then use a hole saw to make a larger dia. hole for the mount to fit flush against the exterior skin, then use the pilot hole again to center the 3/4 saw, unit-bit or punch.

va3wxm · Post by **va3wxm** » Thu Oct 06, 2005 2:56 pm

Thanks for the tips fellas!

The car is (don't laugh) a Saturn ION. The spot where I'd like the mount to go has the inner "frame" against the outer sheet metal skin. It doesn't look welded, just two layers of sheet metal.

There's another spot further forward (that is towards the rear window) that only has the outer sheet metal skin to drill through.

g0dl355 · Post by **g0dl355** » Thu Oct 06, 2005 3:02 pm

va3wxm wrote:Thanks for the tips fellas!

The car is (don't laugh) a Saturn ION. The spot where I'd like the mount to go has the inner "frame" against the outer sheet metal skin. It doesn't look welded, just two layers of sheet metal.

There's another spot further forward (that is towards the rear window) that only has the outer sheet metal skin to drill through.

I'd go through the one closer to the glass if the antenna will clear when you open the trunk. Makes it easier anyway

601 · Post by **601** » Thu Oct 06, 2005 4:01 pm

Can't do it close to the glass unless you're using a 1/4 wave,

I used to have an Ion with a trunk lip mount, antenna always scraped on the glass. The trunk opens straight up, and since there's not much room to mount anything on there, it kinds limits your choice. My car had a spoiler, which meant even less room

Before the centered 1/4 wave, I had a 5/8 dual band on the passenger side with a trunk lip mount.

va3wxm · Post by **va3wxm** » Fri Oct 07, 2005 4:35 am

Nice pic there 601. My ION is the same colour!

I know what you mean about hitting stuff. I currently have a Comet RS-720 lip mount on the driver's side and opening the trunk causes the whip (Larsen NMO150) to run along the side windows. I don't open the trunk that much but it's getting really annoying that when it is open I can't open the rear doors.

There isn't anything technically wrong with my current setup. I just want something that looks a little less hamsexy while not being too whacktacular.

601 · Post by **601** » Fri Oct 07, 2005 4:56 am

I had to switch mine because the center load was hitting the side molding, and started to make gouge marks. I know to be careful when opening the trunk, but anyone else who opened it just lifted it and, smack, right on the side.

The 1/4 wave VHF antenna I had centered was slightly bent towards the back. It still hit the glass, but diddn't seem to be doing any damage.

va3wxm · Post by **va3wxm** » Mon Oct 10, 2005 12:59 pm

One additional question to the experienced installers out there:

Is it better to drill from above or below?

apco25 · Post by **apco25** » Mon Oct 10, 2005 6:54 pm

That depends on where you are drilling, clearance issues and the like. DO whatever is easiest.

giguchan · Post by **giguchan** » Tue Oct 11, 2005 12:22 am

Hello,
I always use a chassis punch...it makes a nicer cleaner hole,But i think drilling is ok... they are not that expensive and work real well.. you might want to try that for the next time.since you are working on the trunk you have access to both sides of the trunk. pretty easy not like removing the headliner like i had to do. on my 05 chevy TB,
Good luck.
Gig

apco25 · Post by **apco25** » Tue Oct 11, 2005 1:23 pm

Green Lee hole punches (3/4) not 3/4 dia with is actually 7/8 work great also the fabulous UNI-BIT can't be beat.

601 · Post by **601** » Tue Oct 11, 2005 7:21 pm

On my install, we drilled from above. Just be careful, the metal does dent pretty easily on the trunk of the ION if you put too much pressure down on it.

fire-medic8104 · Post by **fire-medic8104** » Wed Oct 12, 2005 1:10 am

I normally just use an antenna hole saw. Works fine. You can drill from below or above, though normally I use go from up top with a measuring tape to ensure it is centered.

After I check the bottom of course for anything that I may hit.

One thing I like about the antenna hole saw is I haven't found a vehicle yet that I need to remove the headliner. The bit stops you from going that deep.

I just pull the headliner down to make sure nothing is there, drill and pull the headliner down again to vacuum up the pieces.

Even made me a little adapter that plugs into my shop vac that is stainless still pipe about 1/2" in diameter and at the very end it has a slot cut in the side of the pipe to suck it all up.

va3wxm · Post by **va3wxm** » Wed Oct 12, 2005 4:47 am

601 wrote:On my install, we drilled from above. Just be careful, the metal does dent pretty easily on the trunk of the ION if you put too much pressure down on it.

Okay I'll keep that in mind. I imagine that if your saw is sharp it shouldn't take much pressure to drill through, no?

I'm still torn whether to drill it where the outer skin and the inner rib sandwich together, or where it's just outer skin.

I don't have a spoiler so there's a bit more real estate to work with.

Oh, and I called around to some local 2-way shops and they want $85 minimum to do the deed!

kb0nly · Post by **kb0nly** » Wed Oct 12, 2005 9:35 am

Or get a 3/8" NMO mount, a lot easier to install for beginners, or experienced installers for that matter.

My installs make use of 3/8" mounts 99% of the time, easier to drill a nice clean 3/8" hole with a sharp bit, than drilling a 3/4" hole.

That last 1% is when i have to install a high frequency mount, GPS, WiFi, since i haven't found a source of sealed 3/8" hole mounts.