Hey guys... I just went to a local custom shop and they told me that I needed to get a box made out of FIBERGLASS for the compartment in the back of my 88 Iroc...They said it'd be about $650 and 3 days work..

Can someone just tell me what the differences between Fiberglass and wood are and why do I need fiberglass?

Thanks a lot,
Dan

'88 IROC - SLP Exhaust
2 12" JL W3's.

 

Fiberglass can be used to construct a box that fits the exact shape of your car. This is an advantage because you can use more of the space. With a wooden box, you go as close as you can, but you still waste space. To get a total of 3 cubic feet of space, a wooden box needs to stick up above the floor by about 3 or 4 inches. If you use a fiberglass box that's shaped to the car, it will sit a lot lower and still provide the same airspace.

But, as you saw by the price, the materials and especially the labor involved with fiberglass boxes is pretty high. The end results can be very impressive though.

In terms of strength, the fiberglass can usually be thinner than the wood, but it's going to need to be braced to compensate.

I've built fiberglass kick panels, but I haven't built a fiberglass sub enclosure yet.

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The IROC Homepage
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"I didn't know a bored out Ford could go so slow" -Shenandoah

 

Thanks Jim for the info... another question I have is whether or not I will get the same volume and quality from a fiberglass box and a wooden box. I see that you build wooden boxes, and they look great, but soundwise, will the quality and volume be comparable to a fiberglass box?

Thanks,
Dan

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Daniel Galley
'88 IROC

 

There will be no sound difference between a properly braced 3 cu ft MDF box, and a properly braces 3 cu ft fiberglass box. Like jim said, the fiberglass lets you conform to a irregular shape much better. I have done an MDF, dual 10 box that came to 1.2 cu ft total space in the well of a 3rd gen. It sat 2 inches above the level of the side shelves. If I had done it in fiberglass, I probably could have had it even with the side shelves at the same air space.

mike

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custom 3rd gen kickpanels at http://www.lachernet.com/kickpanels

 

One question, how are the Q-logic custom boxes made to fit our cars? They sell them in Crutchfield for $299 for 2 10" and I think $319 for 2 12". Are these worth it? How do they sound? Let me know. I am thinking about getting the Q-logic box with 2 Infinity subs. I am not sure if I want 10" or 12". It is either the Infinity Reference, or the Infinity Perfects. I might just go with the Reference subs since they are cheaper, they sound great, and because I will never be able to fully power the 1200 watts they can with hold.

 

The fiberglass sub-box I built in my article is actually a combination of fiberglass and wood, and reaches a thickness of two inches on the surfaces that aren't directly supported by the floorpan. There are different techniques for a "proper" box between the two mediums, but the sound quality is comparable. The weight savings is nice, too.