Mazda 3 hatchback NMO drill install

[craneoperator99]

Hey all,

Looking for advice on how to best install an NMO mount on the center of my Mazda 3's roof. So far I've read a bit into this on the forum's and watched some videos. I can't find any posts from anyone who's drilled a smaller mazda sedan like this and am wondering if anyone has any experience or tips?

I did do some poking around trying to find if there is a way I can get between the headliner and the roof. It looks like the dome light in the back isn't that great of an option and neither is the light up front...so I might have to drop the headliner. In that case, I'd be wondering if anyone here has ever dropped a headliner on a mazda sedan?

 

[R8000]

Normally you do not have to drop the entire headliner. You only need to be able to peek in from the side with a flashlight to ensure there's nothing in the way of where you want your hole. Things like wire harnesses, roof braces, side airbag equipment...etc. You don't want to drill into any of those !

With my truck, I found a YouTube video of someone replacing a damaged headliner and paused the video when they showed it all removed and the bare roof showing. I was able to see all the braces, harnesses...etc. I took a screenshot and printed it out and took out with me when it was time to drill. You could be creative with searching for pics, videos of folks fixing other things that involve the headliner area for tips.

Good luck !

 

[mmckenna]

Shouldn't be to much of a challenge.

I agree with R8000, you shouldn't need to drop the headliner completely.
Usually there's some weatherstripping around the door and you can -carefully- put it down where it meets the headliner. Carefully tug the headliner down and see if you have visibility to the underside of the sheet metal. Essentially what you are looking for is to see if there are any crossmembers in the way. If there are some, measure where they are from a known point you can see both inside and outside the vehicle. Transfer that measurement to the roof top on a couple of strips of masking tape.
Center left/right and then go through and double/triple check all your measurements.
Then fire up the drill and go slow.
Route the coax down one of the pillars, making sure that if there are side curtain airbags you route between them and the roof.
Put the weatherstripping back in and finish routing the coax.

Nice to see someone trying to do it right. Ultimately, I'm sure you'll be happier with the permanent install.

 

[OhSixTJ]

They make a hole saw that will keep you from putting a hole in your headliner. If you get one from Home Depot, buy a thin sheet of aluminum that you can slide between the roof and headliner if you want that extra protection.

 

[ClemsonSCJ]

I would highly recommend getting a hole saw bit specifically designed for NMO mounts. I have a Laird brand one and although not cheap compared to a regular 3/4” hole saw bit, it’s worth its weight in gold if you’re not wanting to pull the headliner down. The first time I did my Jeep I pulled the headliner down and it was less of a bear than you would think. If you have a sunroof, most vehicles attach the headliner by magnets so a lot of times you can pull that down to get a good look up in there.

The pros of pulling the headliner all the way down is you can get in there good to make sure nothing is going to interfere with your hole (your roof typically will have cross-members for stability every so often), and you can drill it from the underside to prevent the metal shavings from slinging all over your roof. I’ve heard people say leaving them can cause scratches and rust issues. If you drill from the top side, use a magnet in a plastic baggy so that you can contain the metal shavings in something and makes them easier to pull off the magnet. That or hose the car off after you get the NMO mounted. I would definitely not wipe them off.

Your headliner is typically head up by the plastic pillar columns on either side and dome lights and stuff like that. So as easily as they can be taken loose, so can your headliner.

 

[slowmover]

It seems like a pain ($$) to spend money on what could be a one-use tool.

Instead, multiply it by number of family vehicles and toss in some friends and neighbors. Don’t lend it, be the operator.
.

 

[Omega-TI]

You guys have more balls than I do. If I ever decide to put an antenna on my car, I'll take it back to the people who installed my Blackvue DR900S-2CH dashcam system. Like most automotive stereo outfits, they're used to tearing into a multitude of assorted vehicles on daily basis... and they are also insured.

 

[mmckenna]

they're used to tearing into a multitude of assorted vehicles on daily basis... and they are also insured.

And they're also stereo installers, which isn't the same as an experienced LMR technician. I've had to fix a lot of stuff that was screwed up by stereo shops because someone was trying to save money.

I'm totally good with people not wanting to do stuff like this themselves. It does take a skillset that not everyone has, plus it takes some cajones to do the first one. A reputable two way radio shop will do the job correcty… and they are also insured. Plus they'll properly install the coaxial connector for you with the correct tools, and if you are nice, they'll sweep your antenna to confirm it's all working correctly.

 

[n3obl]

Yeah a stereo installer is not going to have a proper NMO drill bit. I have three of them and use them extensively for antenna and lightbar holes.

 

[OhSixTJ]

It does take a skillset that not everyone has, plus it takes some cajones to do the first one.

Ain’t that the truth! 7 holes later and I’m drilling one in the roof of my brand new Sierra fresh off the lot with less than 100 miles at 10:30 at night because why not. Fun times!

 

[mmckenna]

Ain’t that the truth! 7 holes later and I’m drilling one in the roof of my brand new Sierra fresh off the lot with less than 100 miles at 10:30 at night because why not. Fun times!

Many years ago I did my dad's truck. He picked it up at the dealer and drove it straight to my house. I think the ink on the bottom of the paper would have still smudged while I was drilling the hold.

While I don't do them often, the trucks at work are much easier. A bit less personal attachment.

 

[bharvey2]

You can usually get by with dropping one side (or the back of the headliner if it's a hatchback). Make sure it's still supported in it's lowered state so as not to kink the headliner. I use a very shallow metal pizza pan (but a similarly shallow cooking sheet would work as well, and slide it under the location that will be sporting a new hole. Then I mask off the roof where I'm about to drill, mark and then go to town. The pan under the drilling area will minimize damage should I make a boo boo and will collect drilling debris.

With regard to the actual hole saw, ClemsonSCJ offers solid advice on getting a purpose built hole saw. While I use a standard, off the shelf saw, I scrutinized the tooth pattern and "mic'd" the O.D. of a few brands until I found one that I thought was suitable. Buy Once, Cry Once just might apply for this application.

Oh and once it's all in and running, I think you'll be glad you did it right.