Author Topic: sub in spare wheel well?  (Read 7732 times)

Offline Bluefox

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Re: sub in spare wheel well?
« Reply #10 on: 08 December 2006, 00:07 »
You'd have to seal the gap between the bottom of the false floor and the boot floor surface, otherwise the cc calculation of the well would be incorrect.

So, if you're hell bent on using this space, take some dims of the wheel well, calculate your available cubic space and buy a driver that will work on this space (most drivers will state the thiele parameters on the box, which will allow you to calculate the amount of space required/ideal space).

Yeh, this is what I should have said :)
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Offline golfpro

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Re: sub in spare wheel well?
« Reply #11 on: 08 December 2006, 08:49 »
possibly, sounds like a lot of work for very little benifit though.

thats the best mk3 ive seen..ever! its just clean and subtle.. :cool:

Offline S11EPS

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Re: sub in spare wheel well?
« Reply #12 on: 08 December 2006, 09:23 »
OK, I did a few quick calcs.

Assuming you can fit a 185/60/14 wheel/tyre in your spare wheel well then you have a spare wheel well of approximately 23" diameter:

Tyre depth (mm) = 185mm*60% = 111mm
Total wheel diameter (mm) = 111 + (14*25.4) + 111
Total wheel diameter (mm) = 111 + 355 + 111
Total wheel diameter (mm) = 577mm
Total wheel diameter (in) = 22.7" (say 23")

1 cubic foot = 1728 cubic inches (12*12*12)

Assuming you were running a JL8W3v2 with a required enclosure volume of 0.79 cu ft the enclosure volume, expressed as inches, would be 1728*0.79 = 1365 cu in

A slightly rectangular enclosure (totally square boxes are not as good as those which are not, as the sound can cancel intself out) of EXTERNAL dimensions of approximately 17" * 14" will fit snuggly in the spare wheel well (IE a rectangle within the circular spare wheel well).

Assuming you are constructing in 0.75in material, these dimensions are reduced to 15.5" * 12.5", giving an internal surface area of approx 193 square inches.

If we divide the required volume of 1365 by the surface area of 193 we arrive at the required INTERNAL height of the enclosure, which is 7" (will measure 8.5" externally). This figure should be increased slightly to make allowance for the volume displacement of the driver itself.

Now, obviously, if you aren't using a driver with such a low enclosure volume requirement you will need to increase the height of the box - all you need to do to achieve the look you want is to increase the height of your new false floor accordingly, so the enclosure top and the new boot floor are to the same level. The boot floor is then cut to go around the (rectangular) enclosure and the whole thing can be carpeted as one item - this saves all the hassle of trying to build a round box, or cutting a round false floor around it etc etc. It also means you do not have any sealing issues etc, as its a simple near-square enclosuredropped into the spare wheel well - which also means it will take 10 Min's to tally remove from the car and return it to standard.

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Offline golfpro

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Re: sub in spare wheel well?
« Reply #13 on: 08 December 2006, 09:33 »
good thinkin, makin a square peg fit in a round hole! genuis!

thats the best mk3 ive seen..ever! its just clean and subtle.. :cool:

Offline S11EPS

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Re: sub in spare wheel well?
« Reply #14 on: 08 December 2006, 09:38 »
good thinkin, makin a square peg fit in a round hole! genuis!

I do my best  :wink:

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Offline Len

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Re: sub in spare wheel well?
« Reply #15 on: 08 December 2006, 09:55 »
Excellent S11EPS! Very well thought out!


Oh just a little tip - if you convert inches to a decimal of a foot then its easier to calculate cu ft!
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Offline S11EPS

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Re: sub in spare wheel well?
« Reply #16 on: 08 December 2006, 10:44 »
Excellent S11EPS! Very well thought out!


Oh just a little tip - if you convert inches to a decimal of a foot then its easier to calculate cu ft!

I chose to show it as that as few reading this would know what 0.24 of a foot looks like - expressing it all as inches is easier to relate to, for this purpose.

One calculation (12*12*12) gives you 1 cubic foot represented as inches and then you can continue to work in inches, which normal people will be able to understand.

Don't make me break out the yellow pad and go QS-style on your ass.

Inches are sh!t anyway, I'm a mertic boy - bring on the mm


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Offline Len

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Re: sub in spare wheel well?
« Reply #17 on: 08 December 2006, 10:52 »
fair enough, it wasnt a critism just thought it would be easier for those that are not used to converting imperial to metric!
Personally I have always been versed in both but of course metric is far easier!

yellow pad? dim paper is usually blue! :wink: :grin:


I was appaulding you for doing all that work!
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Offline Uku

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Re: sub in spare wheel well?
« Reply #18 on: 08 December 2006, 15:00 »
aye cheers thats basically what i was thinking along the lines of. the bonus is you can hide the amps either side of the enclosure as well if you make a false floor in the exact shape of the boot, totally stealth then! , also im sure by having the sub centred and facing up (ported is a thought?) its going to have better acoustic propertys than one to one side. im going to go for this i think as i enjoy building my own stuff , i just obtained a perfect rear parcel shelf off ebay to replace mine which has 6x9's cut into it atm ,  which ill lose once i get a sub and amp , then also construct a set of door pods (that guide for custom doorpods is awesome and ill do that :p ) as ive already got top notch wiring for the 6x9's , when i remove them ill use that wire to power the door pod speakers :) just a matter of rewiring each ends.

Offline Bluefox

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Re: sub in spare wheel well?
« Reply #19 on: 08 December 2006, 22:15 »

represented as inches and then you can continue to work in inches, which normal people will be able to understand


Finally! Someone who agrees with me! :laugh:
Bluefox
Current: '84 Golf C 1.9 TDi | '01 Polo GTI | '01 Audi A2 TDi | '83 MG Metro
Previous: '83 GX | '04 R32 | '93 VR6 | '86 GTi 8v | '88 Diesel | '92 G60 | '04 Skoda Superb TDi | '90 GTi 8v | Plus many more!

Project Thread - http://www.golfgtiforum.co.uk/index.php?topic=270683.0