Fiberglassing (FAQ)

From Nissan 350Z & 370Z Wiki

How do I mount the enclosure once i'm done building it? 

The best way, in my opinion, to mount any box is to bolt it to your car. Now not everyone likes drilling / bolting into their car so I will provide an alternative. As far as bolting goes, simply put the box where you want it -- remove the subwoofer, and through the subwoofer hole, drill through the enclosure as well as through the car. Then use a metal bolt and bolt it down, apply a bead of silicone if you are worried about air leakage. It might be a good idea if you have your fiberglass box right up against a metal part of a car to apply some sound deadening material between the fiberglass and the metal -- Otherwise its likely itll vibrate and make lots of noise. If its up against carpet you dont need to worry about this. Now, if you dont want to bolt, you can use hook and loop tape. Not the regular fabric velcro, the heavy duty plastic hook and loop stuff -- Its self adhesive, so apply to your car body, and to your box. Since the box was conformed to that space in the first place, it doesn't take a whole lot to keep it still -- it will just sit there. Always mount your box, its not a good idea to have a huge heavy peice of metal just chilling there, especially if you get into an accident, that shit could fly around.

Where can I get these supplies?

• Fiberglass and Resin: Available at home improvement stores (Home Depot / Lowes), even Walmart carries it. But these are usually small quantities and overpriced. You can get much better deals from boating stores. Look for a local boating shop, or visit http://westmarine.com and look for a local dealer. For a gallon of resin with hardener you should be paying <$20.
  
• Fiberglass Roller: You can use small metal paint rollers, and soak in acetone between coats, or there are many online retailers selling it cheaply. I've seen rollers in a few boat stores as well.
  
• Body Filler / Glazing Putty: Bondo is available everywhere (Auto parts stores, Walmart) but is not as good as some other stuff. Rage Gold or Evercoat are better choices but might be harder to find. A body shop will definitely carry these. You can of course find these materials online but alot of the time these are heavy and shipping costs will kill you, or depending on the product, sometimes you need to pay extra for 'hazardous' shipping, so try to find it locally.
  
• Carpetting / Grill Cloth: I always buy from partsexpress.com. I havent been able to find a local dealer with decent stuff.
  
• Fleece / Fabric: Ragshop or Joanne's fabric or Walmart. Look for polyester/cotton or polyester. Not too thick. Dark colors better. Lower price better. Must be stretchy in all directions.
  
• High build primer: Automotive body paint shops

I want to fiberglass to plastic, how do I do this? 

Incase you didnt know, fiberglass does _not_ stick to plastic. If you glass to plastic, it will fall off once it dries. The only real way around this is to scuff up the plastic (sand with low grit sand paper), then drill a bunch of small holes through the plastic. you then have to glass on both sides of the plastic, making sure resin soaks through the holes and will hold it together. In most cases when you are dealing with plastic (i.e. installing TV in dash, making your own HU mount), you can use plastic weld and cut pieces of ABS plastic. Cut the plastic framing / ABS to your desired shape. Use plastic weld to glue all the plastic together. Then bondo the creases, sand, primer, paint. If you do not know what plastic weld is, you need to get something like Duramix 4040

My resin gel'd, What do I do? 

If it's gel'd up, it's useless. Try to remove any from your structure before it fully hardens -- you dont want pockets of resin only. Resin will gel up when you have applied too much hardener. Remember you only need several drops per oz's of resin, and dont forget to take into account the temperature of air. Manufacturer recommendations are for 70F, if its warmer add a littler less, if its colder add a littler more. Also, brands differ to, if you buy different stuff read the labels.

My box won't harden, What do i do? 

Too little hardener or its too cold outside. You can try adding heating lamps or a blow dryer to speed up the process. If it does not dry (or get tacky to the touch) within 10 hours you can try to add a hotbatch. That is, mix up a new batch of resin and put in 2-3x the recommended hardener and apply it immediately, hopefully this will harden the layer underneath.

My box rattles against my car. 

Apply sound deadening between the box and your car -- You can use some carpetting, dynamatt, brown bread etc. A cheap alterantive is self-adhesive roofing asphalt found in Home Depot in the roofing aisle. Its aluminum foiling with sticky tar on one side (almost identical to Dynamatt, but much much cheaper).

How do I wire up the subs? 

If you want to use terminal cups, you will need to make a wooden base for them to screw into, and glass that into place. However, in my experience terminal cups usually leak. I usually just drill a small hole for the wires to pass through. Tie a knot on the outside so that the wire will not fall into the box. Apply a bead of silicone around the edge (on the inside) to ensure its air tight.

How do I calculate the volume of the box? 

The majority of fiberglass installs are in sealed boxes. This is because ported / bandpass / TL boxes are very very dependant on box size for proper tuning. In a sealed box you can be off on volume by as much as 20% and not hear any audible difference. So usually, you can just guestimate the size of the box. If you are picky, always try to make the box as large as possible. Once you have it completed, you can fill the box with sand / water / packaging peanuts. Then empty that stuff into something of known volume (shoe box, milk jug) and add it up that way. That will give you your exact internal volume. If your volume is too big for what you like, add some mass inside (2x4 chunks glued down). If its too small, you can add some acoustic stuffing on the inside to try to accont for a smaller box. If it still sounds bad, you can cut off some of the box and add to it -- simply glass more, a new glass peice will adhere to the old no problem.

Fleece covered in resin is pretty strong, do I really need to use fiberglass to? 

Absolutely, the resin is kinda like glue that is all. By itself its not very strong, and very brittle. It also likely will not be airtight. You have to use fiberglass or carbon fiber. The purpose of the fleece is only to create the shape, it does not give any strength.

What else can I use to get shape besides pulling fabric? 

I've seen people use chicken wire and apply weave directly over that, or you can use two-part expanding foam and carve out the desired shape, then fleece and glass (this is used alot for custom doors / door pods).

How can I check to make sure its airtight? 

If you put enough layers on you should not even worry about this, but you can always check by filling with water. There should be no leaks.

Can I use carbon fiber in the same process? Can I lay carbon fiber over fiberglass? 

The process for laying carbon fiber and fiberglass is exactly the same. Carbon fiber is more expensive than fiberglass, but it is stronger. Most people now use carbon fiber simply for looks, so if you want to make you box look nice, i would suggest making it out of fiberglass or wood, then lay just one layer of carbon fiber on top. Carbon fiber comes in weave matts. If you've ever used a weave matt of fiberglass you know that it comes apart fairly easily. With carbin fiber as your finished layer, if you have any holes in the weave it will show through. As you can imagine, this will be easy to lay on long straight runs, but as you hit curves, it'll become more difficult. I would suggest practicing with some fiberglass weave matt before using CF (since it is so expensive). If you can get the glass weave to look right, go ahead and try with CF. A link related to carbon fiber laying can be found here. You can use regular polyester resin, but most people I see doing CF work use epoxy resin. You can find information on different types of resin'shere and that website also is a large source of carbin fiber matts.

I'm confused as to how fiberglass gets attached to wood by simply laying the two together. Do I need to screw them together? 

No. Wood is actually very porous, and when you lay fiberglas over wood, the resin will seep into the wood. When it dries it creates a very strong bond and you do not need to use any glue or screws to hold the two together.

I have a question about how to wire up fans and relays. 

Please check out http://the12volt.com/ there is tons of information about basic electrical wire, specifically for cars.

I want to fiberglass over my dashboard / door panel. What process do I use? 

Unless you are completely rebuilding the shape and/or style of your dashboard or door panel, you do not need to use fiberglass. In most cases you can simply use body filler and proceed with the normal painting procedure in order to get a shiny high gloss painted finish. Depending on the surface type, you may need to use a combination of plastic putties or adhesion promoters. Every car plastic is different so it would be a good idea to do a test patch before you do the entire process. However in most cases, body filler has no problem sticking to plastic.