My truly stealth Superleggera Z4MC Subwoofer Install

[k2pilot]

i've seen more and more "sub install" posts lately and thought i'd post up some photos of my install.

needless to say i was dissatisfied with how most all of the other sub installs used up a significant portion of the trunk and left unwanted wiring or amps exposed... i also didn't want to add a ton of excess weight which i notice seems to be a given in almost every sub install i've seen on any car before, the usage of wood in a car makes me shudder, but c'est la vie, audio shop people are by no means engineers. thankfully, i am! well... sort of..

so without further ado, i give you my jl 8w3v3 superleggera!







to total weight on the sub, enclosure and all, came in at exactly 10.0 pounds, the stock "subs" which i removed, came in at 14.6, so i came out 4.6 pounds ahead.

my trick? using what we use in the aviation world, fiberglass/carbon fiber/composite reinforced honeycomb, it comes out being absurdly strong while very light(and only using 2 layers of glass or carbon)


and to get a perfect mold to the shape of the interior panel, i used a neat trick of covering the entire area the sub would sit in with painters tape, it won't let any resin seap through to the carpet and doesn't stick to the fiberglass/resin all to well, so once your part is cured you simply pull it out then peel the painters tape off your piece, then reinforce from there once you have your basic shape.

as for the amp, i got this little guy and followed the instructions in the sub install thread on bimmerfest, just tapping in to the left/right audio feeds and the signal wire.. then hooked them up to this nice little compact guy,


(image is a link)

total cost was under $300.00, and i couldn't ask for a greater improvement to the sound in the car... i've never done a sub install/audio work in a car before but this just came out brilliantly, i'd say it's a must for any z4mc owner. it's unbelievable just how much "bump" that little 8" sub kicks out... and it integrates so well, once you get the appropriate level of bass you want(on average) you can use the cars EQ/bass control to adjust it according to the song(if you need to) though i'd do that sparingly as it changes the "semi subs" in the cabin a bit with them too.

[ssummers]

Nice work!

I did a similar install in our S2000 with a custom box, used a JL sub and amps, can't say enough good things about JL products!

I plan to do a complete install in our Z as well, thanks for the tips on making the box.

[JCz04Bimmer]

Make a mold!

Great work. My kinda install. Does the box remove easily?

[k2pilot]

Originally Posted by ssummers

Nice work!

I did a similar install in our S2000 with a custom box, used a JL sub and amps, can't say enough good things about JL products!

I plan to do a complete install in our Z as well, thanks for the tips on making the box.

the jl stuff is fantastic, i first got hooked on my m3, prior to it i had never really been around an after market sound system.

the previous owner went a little over the top on the install.


and yeah if you ever have any questions during the process of making your box just post in here and i can give all the advice i can on composites.

Originally Posted by JCz04Bimmer

Make a mold!

Great work. My kinda install. Does the box remove easily?

i considered it, but if i were to make the box again i would do everything a bit beefier and maybe some different technique... and the box comes out extremely easily, it's simply placed in there as the little storage pocket at the bottom acts as a great place holder for it, there's zero movement and it just pulls right out, though i also tossed those rags on top for one to be a rag holder, and second just to help stabilize the box a bit more(not that it was in any way insecure without them).

if anyone wants a box similar to mine(i can change things like the size for larger subs or different tones if needed) then i'm open to the possibility of selling them. i am afterall a starving college student so i've gotta make some money some how.

[Getssum96]

Interested in box! Let me know price via PM Thanks!

Just looked a little closer and realized that you are local, so if you'd like I could even leave the car at your hangar!!!

[nickpapa]

what are the specs as far as internal volume? i believe the 8w3 needs .30cuft of airspace for a sealed enclosure

[3002 tii]

i would so pay for one of these assuming the m-coupe and non-m could use the same enclosures.

[k2pilot]

Originally Posted by nickpapa

what are the specs as far as internal volume? i believe the 8w3 needs .30cuft of airspace for a sealed enclosure

it's definitely more than .3ft^3, and the 8w3v3 takes .37ft^3, if i had to guess, i'd say this is roughly .45ft^3. what i should have done was at some point fill the container with water and measure the volume... but c'est la vie, too late for that now!

Originally Posted by Dubbedown

i would so pay for one of these assuming the m-coupe and non-m could use the same enclosures.

yup, m-coupe and non m are the same, the only difference being the location of the battery.

[crfine88]

Looks great,
I'm doing an 8W3 in the same spot and getting rid of the stock subs.

damn, you beat me to it.

[fitchesbass]

OP, that looks great! The only way I'd do it, if I were to ever install some ICE.

[Graham M]

That choice of amp makes me want to punch babies.

Pioneer FTL

[Z4-VILLA]

impressive

[garto87]

Here did you get that honeycomb material and what is the fabrication process like? Is it similar to fiberglass?

[Hybrid]

Hate to revive a thread from the dead but I'm really interested in building something identical to this. OP, any chance you have the plans from your build or maybe some insight on how I could replicate this?

I want to fill out the low end of the sound system but I also need my trunk. With your solution it seems you can have cake and eat it too.

[k2pilot]

Originally Posted by Hybrid

Hate to revive a thread from the dead but I'm really interested in building something identical to this. OP, any chance you have the plans from your build or maybe some insight on how I could replicate this?

I want to fill out the low end of the sound system but I also need my trunk. With your solution it seems you can have cake and eat it too.

Unfortunately I don't have any plans, Generally I only do these sorts of things on a case by case basis.


If you want to make this the easiest way possible, completely seal and protect the area you want to work with, then fill it with any sort of mildly expanding foam, then use that foam as a plug for your completed box.

In step by step form, this is what I'd do:

1. Put down a first layer of painters tape against your car's trunk liner, then build off that with more layers of tape to make a nice solid barrier between the cavity that you'll be filling with foam and your trunk liner, this is to make sure no foam can seep through and bond to your trunk liner.

2. Cut out some plastic or wood panels to act as walls in conjunction with your tape barrier, these walls should work with the tape to make a nice cavity for you to fill.

3. Coat all the interior surfaces with a mold release wax or other compound.

4. Get a can of "Great Stuff" sealing foam and start to fill the cavity from the bottom up, leaving a decent amount of room at the top for you to get the foam plug out when it's complete.

5. once the temporary foam plug is done curing, remove it from the cavity.

6. Now that you have a foam plug of all the complex curves you need to build off of, You can then coat that plug in fiberglass or whatever you feel like using, and if you really want to get fancy, vacuum bag it.

7. Once you have a composite portion of the complex curves complete, you can just attach on the solid faces of honeycomb or whatever material you'd like to use in roughly the same previous locations of the last panels you made up to seal the chamber. in the M Coupe (and most cars) you just get away with having the face and top in honeycomb.

8. Once you have a completely sealed box, put some reinforcing glass around all the seams (don't want any air leaks!). At this point your box is 85% done, just cut holes where you need to and then coat it in some carpeting material (available at most any audio stores where they do this sort of work). I just used some spray 77 and stuck the fabric right on.

I found some photos of the box in progress, nothing very useful though. they're showing something around step 7.


I've been able to fit some of my 6' talls friends back there when the occasion called for it. I think the tallest being something around 6'2", needless to say he wasn't comfortable, especially when the subwoofer started to bump...