Custom Sub-Box "IN" Spare Tire
 

This is in progress and I'll insert notes later.

I can't post anymore pictures; it says the post has exceeded the limit. So you have to navigate over to this photo album. Start at the last phot and work backwards if you want to see the progress from start-to-current.

Nissan 370Z Forum - jikhead's Album: Custom Sub-Box IN Spare Tire

OK, so here's what I've got going on...

I bought a Pioneer TS-SW2501S4 and it's mounting depth is 3" and the recommended air space is 0.45 cu.ft. (min 0.35 & max 0.7). Pioneer's manual also recommends 3/4" MDF, which is what I bought.

So I've cut out varies sizes to try and contour the wheel here. I did it to try and get as much cubic air space as possible. Now, just looking at it when I stack them...I'm pretty certain there's going to be at least the min cu.ft. The manual does state the figures above include the speaker displacement. You wouldn't think so when you place the speaker up to it. But if you visualize a 0.5 cu.ft is 6"x6"x6", there will be this much space...just not in a square shape of air..but all around the speaker. It would definitely be easier to cut all the pieces the same size, and then leave the top piece wider. If I do another, I may attempt this to just to see. I've got enough MDF left to do 2-3 more boxes, so I may do some experimenting and build some more. So, you can see that they are staggered in size from bottom to top. When stacked, it somewhat resembles the Bose sub in a way. I will provide the measurements of each board later, as all this is at the shop at work. Now, I used a Rotozip w/circular cutout tool. Not all of my cuts are completely circle and perfect. I made some cuts that were slightly too big, and it needed to be trimmed. It's too hard after the fact, using the Rotozip, so I ended up doing all my trimming work on a bandsaw. When I used the bandsaw, there goes my perfect circles. So now, I plan to take board #2, cutout the inner piece of it, leaving a 3/4" ring. I'll repeat this as I work my way up the boards. Each board up will have a ring slightly larger. This is because the inner diameter rings will be flush; the outer diameter will not since the boards are tapered and staggered in size. Hope you follow me there. I'll repeat this until I get to the top #6 board. My Pioneer speaker package came with a cutout template built into the cardboard packaging. This will be used to make the speaker cutout. Next will be using liquid nails to glue each piece together, and use sheetrock screws as well. You'll notice that the screw will not go all the way down into the MDF board, leaving an air gap when stacked. I went back to Lowe's and didn't see anything else that would really help. So, I will drill out a little depth for the screw head to sink flush/or below the level of the MDF surface.

I'll pick back up tomorrow. I plan to cut something in the top board so you can grab it and pull it out. Don't know whether a hole for your hand to fit in, or attach rope, or what yet. I also will carpet it, and put a speaker terminal cup. This will probably have to go on the bottom.

Also, there's probably going to be an issue with the box rattling. Another member mentioned this with his. If you think, when the sub is bumping, I foresee it maybe jumping up and down a little inside the wheel. The wheel may need to get some foam or something too, to keep it from moving around.

Looks good so far. Were you going to leave that screw that holds the spare down out?

Reading your post just instantly gave me an idea to make this work, thanks.

Beforehand, I had not considered and didn't know of a way to make it work. What if a small hole is drilled in the bottom of the box (so my bottom board) and the screw goes inside the box to screw the spare tire down? This would work; just need to cut off some length of the rod. What do you guys think?

I've uploaded today's pictures to the photo album. I had to delete some from yesterday to make room. So if anyone is looking to see additional photos from Day 1, some additional Day 1 photos may be in this thread at the top.

I would think the weight of the sub and box should hold the spare down. I wouldn't compromise the box's integrity.

So I cut out all the rings today. You may notice that most of my cuts are not perfect circles again! So shoot me! I must admit it's not easy using this circular tool with the Rotozip. On several occasions, the tool widened itself as I'm applying pressure to it and the RZ; causing my circles to get out of wack or entirely ******. My top piece somehow got screwed when I was making the speaker cutout, and had to make a new top piece.

Once I make all the rings, I stacked them up so I could try and calculate the cubic feet. My measurements were 12.75" x 12.75" x 3". This came out to only 0.282 cu. ft. Oh snap! The recommended was 0.45 & the MIN was 0.35. After some serious thinking, I decided to take the bottom piece and cut it into a ring to give me an additional 3/4" in height. I calculated this into the equation and it gave me 0.353 cu. ft....just enough for the MIN. I then went to Home Depot and picked up a small precut piece of 1/2" MDF to cut my bottom piece for the box. The reason I didn't use any existing 3/4" MDF is because I was trying to keep the box recessed so the speaker w/speaker grille would sit flush with the large foam piece in the hatch area. Thus, keeping everything as stock. Using another 3/4" would raise the box up and above the foam piece by a 1/4" (even higher w/top part of speaker height). Using the 1/2" piece of MDF makes the box sit flush with the foam. Now, I must decide what to do about the top part of the speaker being raised up. The plastic piece and carpet mats won't sit flat anymore because of the speaker height. My only thought right now, is to possibly take some high density foam of some sort...glue or velcro several pieces throughout the flat plastic floormap piece...thus raising the surface level of the hatch space up a 1/2" or 1". This would also prevent anything in the storage area from damaging the speaker cone. NOTE***I debated at HD whether to buy 1/2" or .25" MDF. The .25" would've made the box overall height better, but I was concerned with that thickness the overall sound quality and box integrity would be affected. The .25" was a little flimsy where as the .5" you could bend or flex. The box may rattle more if the bottom piece was .25". Anyway, if someone happens to build one and use .25" let me know how it works out.

Please give me any feedback ideas that might help me.

Also, I'd like to point out two major things should anyone be thinking of doing this themselves:

1. My whole idea of tapering/staggering the rings was a waste of time as I did not factor certain things originally. The shortest sheetrock screws I saw & bought were 1.5". If you have shorter screws, it is possible to make this idea more worthwhile and to get some slightly more cubic air space. But to do it with shorter screws, you need to continue to taper the rings as you move up, but also ensure they are thick enough for the screw. I personally think this takes too much extra time to try and get this just right. My inner diameter is the same for each ring, but since I tapered them, each one was slightly bigger and hence took extra time. Since the inner diameter is the same, then there really was no point to taper them. Make sense? If I build another one, I will make the bottom piece and all the rings the same outer diameter and the same inner diameters. This will take much less time because you can just copy the first circle to cut the other; and then copy the first ring for the others as well. However, I would still leave the top piece bigger to make it look more flush with the tire. Just my thoughts so far after today.
2. There's no way anyone is going to get a 12" sub and make it sound effecient according to specs. This 10" is barely going to work as is. I would recommend to everyone to go with a 8" sub if they want to do this box. The Pioneer 8" mounting depth is 2.5" and the recommended cu. ft. is 0.4, MIN is 0.15. So the 8" would probably sound better overall in this box. Plus, the original box design would meet these specs without adding the additional ring layer and would sit lower in the space as I originally intended.

Wouldn't the screw have to go through the box from the inside, thus you wouldn't want it shorter, actually hopefully it would be a bit long to account for the thickness of the 1/2" MDF you are using? Also, wouldn't you have to take your sub out of the box to access the spare tire? Maybe i'm not understanding what you are saying.

That screw is like a foot long or so, because it goes thru the Bose subwoofer and then thru the wheel to meet the threads in the metal frame of the car. So in theory, you would have to cut most of the upper portion of the rod leaving the threaded end. Reattach the plastice turn thing to the rod. Because now the screw only needs to tighten from the 1/2" bottom layer of the box and the wheel. Make sense? And yes, if this was done, you would have to unscrew the subwoofer to get to this in order to take the spare tire out. It may be better to just reinforce the spacing between frame and the wheel to keep it in space and snug. The weight of the box and speaker may be enough to keep the wheel DOWN. Will the box bounce up and down with music? Don't know.

Ahh, OK i gotcha. I have the non-touring so my screw is sized for the spare only without the bose Subwoofer. Seems like if you had to pull the sub out of the box to get the spare out you might as well just go without a spare IMO. Probably some way to get it to all fit snug in there without using the factory tire hold down.

Looks great!b:tiphat:

This is similar to what i did a few months ago. I have now finished the install and it looks great. I have not updated the pics because I have been having problems with my camera but tonight will use my phone to take new pictures.

http://www.the370z.com/audio-video/1...pare-tire.html

Yeah, your post sparked me to try this myself because the local shops were going to be WAY too expensive with a custom fabricated one. I'm going to build a 2nd at some point (not anytime soon), and hopefully can build a better one.

That looks like a lot of work! I think it would be better to make a mold inside the spare tire and fiberglass it and then bond the baffle to it. You will gain substantially more air space than the method you are using. With a fiberglass enclosure there you would have enough depth to use a conventional 8" sub which will out perform a flat 10.

also, it seems like the sub sticks out and is not level with the rest of the cargo area components. How will you cover that with the mat, etc and have it leveled and not damage the sub when you put things there?