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staax
09-01-2014, 06:53 PM
Hi guys,

I have been asked to share my experience with creating my own false floor for my 2012 MZ3 Hatchback so feel free to take any ideas if you decide to make something like this of your own. The possibilities are endless so be creative! I do apologize that I hadn't originally intended to make this thread and I didn't take too many pictures of the build stage, only the finished product.

If you want to see exactly how I built my floor, skip this section and scroll down.

So what is a false floor?

Basically, a false floor is a raised bottom that normally hides something below, or creates the illusion that nothing of interest lies below the surface. Now everyone know's that normally you'll only find a spare tire, maybe some oil bottles or jumper cables in the trunk of the car, but not too many people would assume that you have a bangin' sound system beneath the carpet in your trunk.

What's the purpose of having a false floor?

Well first of all, you don't have to have a subwoofer in your floor... you can essentially raise the floor and create an additional storage cubby for items you may want to store in your car. In my scenario, I wanted to 1) have a decent sound system that doesn't take too much space up in my trunk and 2) create something hidden that wouldn't encourage a thief to peek in the side glass of my hatchback and see a subwoofer and try to steal it. While most Mz3 hatchbacks come with the little cover to prevent visibility into the hatch from the outside, some SUV's for example don't. My father had his 2006 RAV4 window smashed as he left his laptop in the trunk of the vehicle. The thief peeked in the side of the glass and decided he want it.

What are the cons with building a false floor?

In my scenario, because I wanted to cram two subwoofers in the trunk of my car I had to remove the spare tire. This may be a deal-breaker for some people but some car manufacturers are no longer giving you a spare tire with your new vehicle; instead you get a mini 12V air compressor which you can buy at Canadian Tire for $50 and a can of Fix-a-Flat. I purchase a tire plug kit and a mini air compressor so I could fix my car on the side of the road if need be. Now I'm aware this would be terrible in the winter time but it's a chance I'm willing to take.

How much can I look to spend if I want to built a false floor?

Because my floor involves pieces of 2x4, a 4x8 sheet of 3/4" MDF, and 3 cans of polyester resin and fibreglass mat I believe I spent around $150. I could've built the same box for $100 but I had trouble sourcing out some materials. You can also build just a wooden sub box for about $60.

What do I need to build a false floor?

Materials list to the best of my knowledge:


5/8" - 3/4" sheet of MDF
2-3 1L cans of Polyester Resin
3 Packages of 9 sq ft. of Fibreglass Mat
3-4 2x4's
Painters, masking, or aluminum tape
Silicone Caulking
Screws
Paint, Carpet, or Vinyl Wrap
Speaker Terminals
Grill or Grate


Tools list to the best of my knowledge

Table Saw
Mitre Saw
Drill
Drillbits
Screwdrivers
Jigsaw
Orbital Sander
Sandpaper
Pencil (for marking)
Air Stapler or HD Stapler
Hammer
6-8 Cheap Disposable Paintbrushes



Now onto my build....

1) First of all, I decided I wanted to fit 2x Alpine Type R's in the floor of my trunk. In order to do this I had to remove the spare tire, so I began assessing the stock form of the car with the spare tire removed. Ignore my amp in the top left - this is not where I'll be placing it.

http://i42.photobucket.com/albums/e324/x2daz11/False%20Floor/IMG_20140813_131103_961_zpse26929cb.jpg (http://s42.photobucket.com/user/x2daz11/media/False%20Floor/IMG_20140813_131103_961_zpse26929cb.jpg.html)

2) Next I began measuring the dimensions of the frame for which I used pieces of 2x4. If you don't want the stock floor to be raised by too much you can use pieces of 2x3 or 2x2. I assembled the frame as follows, at this point I do not have the other piece of 2x4 on the left hand side of the spare tire well which I used to mark the end of my fibreglass box and the beginning of my storage cubby.

http://i42.photobucket.com/albums/e324/x2daz11/False%20Floor/IMG_20140813_152518_508_zps20070bd7.jpg (http://s42.photobucket.com/user/x2daz11/media/False%20Floor/IMG_20140813_152518_508_zps20070bd7.jpg.html)

3) I then taped the inner spare tire well with green Painter's tape in preparation for my fibreglass mat and resin. I would recommend using aluminum tape before the painter's tape just to ensure no fibreglass resin seeps through as you apply your first coat. In my case it did.

4) I then applied the first coat of resin and fibreglass mat and let it cure. Once cured I could remove the whole assembly from the vehicle to apply additional layers afterward, again my apologies I didn't take pictures here but here is a good guide for you!:


https://www.youtube.com/watch?v=xulDFGYpg0o

5) Once removed, I applied additional layers of fibreglass mat and resin to give the proper strength the box needed. Keep in mind that the strength comes from the strands of fibreglass mat which is horrible, messy crap if I may add. The resin "melts" the mat into the structure of your box. Please read other threads on how to properly fibreglass as I could spend a day explaining it. Here are some photo's of the box with around 5-6 coats of fibreglass mat and resin applied drying outside of my car, pleasure excuse the texts at the top - I was trying to explain to my girlfriend to take the pictures I needed. (LOL!)

Top:
http://i42.photobucket.com/albums/e324/x2daz11/False%20Floor/Screenshot_2014-08-18-12-46-22_zpsfd4fdabb.png (http://s42.photobucket.com/user/x2daz11/media/False%20Floor/Screenshot_2014-08-18-12-46-22_zpsfd4fdabb.png.html)

Top2:

http://i42.photobucket.com/albums/e324/x2daz11/False%20Floor/Screenshot_2014-08-18-12-54-40_zpsabff0691.png (http://s42.photobucket.com/user/x2daz11/media/False%20Floor/Screenshot_2014-08-18-12-54-40_zpsabff0691.png.html)

Bottom, note the little notch in the centre from where the spare tire bolt threads into the floor:

http://i42.photobucket.com/albums/e324/x2daz11/False%20Floor/Screenshot_2014-08-18-12-49-17_zpse93f1482.png (http://s42.photobucket.com/user/x2daz11/media/False%20Floor/Screenshot_2014-08-18-12-49-17_zpse93f1482.png.html)

Side, see the formation of the spare tire well:

http://i42.photobucket.com/albums/e324/x2daz11/False%20Floor/Screenshot_2014-08-18-12-46-32_zps57006c47.png (http://s42.photobucket.com/user/x2daz11/media/False%20Floor/Screenshot_2014-08-18-12-46-32_zps57006c47.png.html)

6) Once I had the fibreglass and 2x4 shell completed, I cut a piece of MDF to fit on the top and cut my two holes for the subwoofer. I also added a piece of MDF in the the centre to create two individual chambers (1 per sub). I screwed, fibreglassed, and siliconed the piece in place. After I test fitted the top piece and subwoofers I siliconed and screwed it down:

http://i42.photobucket.com/albums/e324/x2daz11/False%20Floor/falsefloor_zps5effcb89.jpg (http://s42.photobucket.com/user/x2daz11/media/False%20Floor/falsefloor_zps5effcb89.jpg.html)

7) I added my two speaker terminals as shown below which have been covered by the following: I placed a bunch of small pieces of 1/2" plywood on top of the 3/4" MDF to create an elevated platform to extend past the lip of the subwoofer. I finished by adding a 5/8" piece of plywood on the top so the floor sits higher than the subwoofer:

The black indicates where I placed my terminals beneath the 5/8" piece of plywood. The red indicates how my wire runs into the terminals (also beneath the plywood).

http://i42.photobucket.com/albums/e324/x2daz11/False%20Floor/9005465d-11ff-4cf5-b908-e7e6a7a013ab_zpsb9364649.jpg (http://s42.photobucket.com/user/x2daz11/media/False%20Floor/9005465d-11ff-4cf5-b908-e7e6a7a013ab_zpsb9364649.jpg.html)

8) I added another piece of MDF to create a small storage cubby for crap, It has a single door hinge on the back. I also lined the side and front of this cubby with foam tape to ensure it doesn't rattle when the subs hit:

http://i42.photobucket.com/albums/e324/x2daz11/False%20Floor/IMG_20140826_152203_535_zpsf91c91ce.jpg (http://s42.photobucket.com/user/x2daz11/media/False%20Floor/IMG_20140826_152203_535_zpsf91c91ce.jpg.html)

9) Night shot:

http://i42.photobucket.com/albums/e324/x2daz11/False%20Floor/IMG_20140823_210425_033_zps95a6880b.jpg (http://s42.photobucket.com/user/x2daz11/media/False%20Floor/IMG_20140823_210425_033_zps95a6880b.jpg.html)

10) Today I added the grate (finally) to protect the subs when they hit. I raised the grate slightly more with the two pieces of plywood which are painted red. I ran out of black paint but the red actually complements the writing on the subwoofer. I stapled the grate into the plywood with an air stapler, excuse the crap on the surface I just came back from a weekend camping trip.

http://i42.photobucket.com/albums/e324/x2daz11/IMG_20150524_182712_249_zpsq2qhmpd4.jpg

11) And lastly with the carpet piece on top, this is pretty much the finished product.

http://i42.photobucket.com/albums/e324/x2daz11/False%20Floor/IMG_20140901_161417_696_zpsb260b546.jpg (http://s42.photobucket.com/user/x2daz11/media/False%20Floor/IMG_20140901_161417_696_zpsb260b546.jpg.html)


Oh and no that isn't the permanent spot for my amp. Still trying to find a good place for it.

12) Lastly, finish this thread by leaving and listening to some good music \m/:


https://www.youtube.com/watch?v=Gtft6LqgFSA



Questions welcome!

bilinz
09-01-2014, 07:19 PM
Thank you for this. Seriously much appreciated!

Default User
09-01-2014, 07:22 PM
Nice write up.

Enclosure looks good

Jackal
09-01-2014, 08:39 PM
Sweet! Nice job and writeup!

Captain Mazda
09-01-2014, 08:47 PM
Thanks for reminding me that Lacuna Coil has a new album out.

kasakato
09-01-2014, 09:36 PM
Looks awesome!

jaimie08mazda3
09-02-2014, 07:43 AM
That is seriously sweet. That is a lot of work to do but you did it perfectly. My only question is what do you have between the carpet and the subs? MDF wood? Just looking at the entire page and I didn't see anything about that. Wondering if you got the subs going and something above it would it not vibrate it around or am I missing something lol. Either way I am jealous. Good way to set up the Type Rs for sure.

Dave_The_BMXER
09-02-2014, 08:43 AM
I would have done the final top portion a bit different myself but over all nice work!

Has the smell of fiberglass left yet?

jaimie08mazda3
09-02-2014, 09:06 AM
Nevermind. The one picture that didn't load for me answered my question. How strong is the steel mesh?

staax
09-02-2014, 09:35 AM
Thanks everyone!

Jamie,

The top piece that the subs sit on and what seals the box is 3/4" MDF. I then used a 5/8" piece of plywood on top of the MDF to make sure the floor sits flush with the lip of the sub. Lastly I cut two strips of 5/8" plywood which I painted red and placed my grate over top. This is just to make sure the subs have adequate movement if I have something in the trunk. The carpet just fits loosely ATM and I'm thinking of removing that plastic piece on the bottom because it will rattle. Otherwise foam tape may work well.

Dave,

Yeah having the subs vertically over each other is different from a lot of false floors I've seen. And the smell has gotten much better, but if the car is baking in the sun with the windows up its pretty brutal. Driving for a few mins with windows down solves that problem.

staax
09-02-2014, 09:38 AM
The mesh was a PITA to put on since I wanted it tight. Its pretty strong. I believe its 1cm " 1 cm and is 20 gauge thick. Lowes carries all kinds so you can get thicker if you like.

jaimie08mazda3
09-02-2014, 10:13 AM
Yea that sounds solid for sure! The MDF wood anyhow. Still kind of unsure how well the 20 GA mesh holds up. Reason I ask is because I work for a steel grating company and I work in the Expanded Metal department and 20GA is the lightest stuff we sell apart from aluminum. I would keep an eye on it just in case. Last thing you would want is something bending it into the subs possibly causing a hole or something. But all in all man good job. I'd like to do this but my 10" will literally touch the bottom of my trunk if I did haha. And I have an issue with a trunk leak.

staax
09-02-2014, 10:42 AM
Actually a piece of expanded metal was exactly what I was after but I couldn't find one big enough, so I went with the mesh.

I'll definitely keep an eye on it thanks - I did put my hand on it and pushed down and it hardly moved. I'll also not put anything too heavy in the center. I went camping this weekend and had the car LOADED with both rear seats down and the hatch filled to the roof and how was before the steel grate (why my girlfriend feels the need to bring 2 and a half bags of clothes for 3 days is beyond me)... that plastic piece underneath the carpet was strong enough so I imagine the mesh will be too.

Appreciate the advice!

DLYDRVN
09-02-2014, 03:21 PM
I don't know if you left it out intentionally.. but did you calculate the volume of the fiberglass 'box' for the subs? If the volume for the driver is two small you'll get seriously compromised LF response, too large and you'll lose definition. I don't know how much space you 'gain' by raising the floor, but I would hazard to guess those 10" Type R's want around .75-1cuft, and a Qts of like .5 ish. I'd bet if you've got them raised in the floor you probably have too much volume in the 'cabinet' to run them efficiently. Might be ok if they're 12"s though I think the 12" Type Rs have a lower Qts, and box sizes up to around 1.2cuft per driver.

Secondly, you're running a sealed cabinet, so you REALLY want to separate the space between the two drivers if you haven't already. You run the risk of damaging the drivers when they share a sealed space like that, or at the least compromising sound quality because of the pressure interactions of the two units.

staax
09-02-2014, 04:08 PM
Two 12's and yes each sub has there own chamber. One is a 2011 the other is a 2012. Step 6 I mentioned that I added a piece of MDF to separate the subs.

I posted the cu ft in another thread. Each has a generous estimate of 1.35 cu ft. And the subs are not powered to their max potential with a xd600/1 so slightly bigger cu ft per sub is no problem.

DLYDRVN
09-02-2014, 04:45 PM
I dont know how i missed reading that ;)

staax
09-02-2014, 05:03 PM
No worries haha, its a long post. But I appreciate the reply!

staax
06-14-2015, 01:43 PM
Adding the new floor pictures:

http://i42.photobucket.com/albums/e324/x2daz11/IMG_20150524_182712_249_zpsq2qhmpd4.jpg (http://s42.photobucket.com/user/x2daz11/media/IMG_20150524_182712_249_zpsq2qhmpd4.jpg.html)

http://i42.photobucket.com/albums/e324/x2daz11/IMG_20150524_183508_982_zpscwesob6b.jpg (http://s42.photobucket.com/user/x2daz11/media/IMG_20150524_183508_982_zpscwesob6b.jpg.html)

http://i42.photobucket.com/albums/e324/x2daz11/IMG_20150524_182725_830_zpszierywxy.jpg (http://s42.photobucket.com/user/x2daz11/media/IMG_20150524_182725_830_zpszierywxy.jpg.html)

http://i42.photobucket.com/albums/e324/x2daz11/IMG_20150524_183102_448_zps5hvjculq.jpg (http://s42.photobucket.com/user/x2daz11/media/IMG_20150524_183102_448_zps5hvjculq.jpg.html)

Captain Mazda
06-15-2015, 10:11 PM
Man that's awesome, you should start a false floor business \o/

staax
10-13-2015, 01:19 PM
Likely going to be parting my car out soon.

Does anyone want this box? Looking for $80 which is less than what I spent to build it.

One catch: I'm in Ottawa but willing to drive half way to to Toronto.

Just getting a feel first then I'll post a part out thread.

Ask any questions you might have.

jaimie08mazda3
10-13-2015, 02:21 PM
Likely going to be parting my car out soon.

Does anyone want this box? Looking for $80 which is less than what I spent to build it.

One catch: I'm in Ottawa but willing to drive half way to to Toronto.

Just getting a feel first then I'll post a part out thread.

Ask any questions you might have.

Are you going standard?

staax
10-13-2015, 03:04 PM
Are you going standard?

Yes haha, but not Mazda :(

jaimie08mazda3
10-13-2015, 03:10 PM
Yes haha, but not Mazda :(

It's alright my next car won't be a Mazda either. But I am gonna keep mine so I'll still be apart of the Mazda life lol.

staax
10-13-2015, 03:19 PM
I bought mine knowing it'd be temporary. The next car I'm planning isn't spectacular, but it is a 6 speed hatch with a turbo.

Ill have this one for 4-5 years and then I'll get into my Charger RT :)

jaimie08mazda3
10-13-2015, 03:36 PM
You know what's funny. Your thinking is the same thing as me. 2.5 turbo AWD wagon 6spd.

staax
10-13-2015, 04:02 PM
Haha well I wasn't thinking AWD. I assume you're going with an Impreza.

I'm still going with decent fuel mileage. Haters gonna hate... 2016 Forte5.

Steering is numb, but rest of car is fantastic and the seats are effing comfortable. I hate my Mazda's seats.

Regardless, Impreza is a beautiful car (unless something else has a 2.5T). Really like the 08-11 Imprezas.

jaimie08mazda3
10-13-2015, 04:24 PM
http://images.tapatalk-cdn.com/15/10/13/2588416e465687c6576f8453f7a420c3.jpg
I'm looking at one of these lol. I don't need new. I want quick and able to add more 13s ;).

Dave_The_BMXER
10-14-2015, 12:16 PM
I looked at those, too long to fit in my current garage lol

staax
10-14-2015, 12:48 PM
Jaimie you should definitely do it and make your own Supergramps!

Dave, expand the garage... Just don't tell the wife :)

jaimie08mazda3
10-14-2015, 12:58 PM
I'm seriously considering it. Plus I need a hatch and I figure this will help me achieve my 150 DB goals lol. And turbo AWD. I have my entire driveway and garage so I can fit pretty well whatever I need to in the winter!

staax
10-14-2015, 01:05 PM
Only thing that's kept me away from Subbie is the boxer engines... Don't like things I'm not very comfortable with haha.

AWD would be awesome though, I'd look forward to wintertime

jaimie08mazda3
10-14-2015, 01:07 PM
2.5 isn't a boxer motor. It's the better built then the 2.0 boxer. And I did Consider one but people do have many problems with them vs he 2.5 which is why I'm opting for the Legacy. And I'm perfectly fine with that!

Dave_The_BMXER
10-14-2015, 01:08 PM
Jaimie you should definitely do it and make your own Supergramps!

Dave, expand the garage... Just don't tell the wife :)

Current house will be old house in just over a month ;)

jaimie08mazda3
10-14-2015, 01:09 PM
Current house will be old house in just over a month ;)

Soooo sell speed and buy legacy? Hahahaha. I've considered the speed but I want AWD.

microtandme
10-14-2015, 01:10 PM
Did you still want to sell the box? Because I would definitely buy it

Dave_The_BMXER
10-14-2015, 01:11 PM
I'll have the speed for a bit yet. :)

jaimie08mazda3
10-14-2015, 01:13 PM
I'll have the speed for a bit yet. :)

It looks awesome and probably loads of fun. I just feel like winter will be so much better in a legacy. Plus insurance quotes me only at 100/month. It's amazing when 5-6 years ago it 6 times as much for my 3 lol.

staax
10-14-2015, 02:17 PM
Hey microtandme

Good to know - I will likely be parting out my car soon so you can have first dibs on the box. Its completely solid and functional and looks good in the car. Please note there are small workmanship defects (ie: screws in plexiglass not lining up equally, rough cuts in some areas of the wood etc). Regardless I'm only asking $80 when I could ask double that.

I'll post more pics of these details of course, just wanted to mention that and that I am in OTTAWA. But will drive to meet half way!

Thanks for your interest!

And grats Dave! I remember seeing that in the home owners thread.

I will post a proper for sale thread with more pics and everything soon.

microtandme
10-14-2015, 02:40 PM
Hey microtandme

Good to know - I will likely be parting out my car soon so you can have first dibs on the box. Its completely solid and functional and looks good in the car. Please note there are small workmanship defects (ie: screws in plexiglass not lining up equally, rough cuts in some areas of the wood etc). Regardless I'm only asking $80 when I could ask double that.

I'll post more pics of these details of course, just wanted to mention that and that I am in OTTAWA. But will drive to meet half way!

Thanks for your interest!

And grats Dave! I remember seeing that in the home owners thread.

I will post a proper for sale thread with more pics and everything soon.

Awesome please let me know when you are parting out