Well these cold days durring winter, I just find myself thinking about new stuff to do. My rear bumper hangs really low, and since I will be traking my car with 700+whp, my traps should be pretty high, and since the rear bumper acts like a parachute, and I want to do anything possible to avoid using those ugly hole in the bumper diffusers, I was thinking about making my own full underbody diffuser (mainly for the rear). I know that I could make this out of metal , but I was just weighing my options, and thought that a fiberglass one might work out well, and I have very little knowlege about fiberglass, but let me run this by and see if you guys think it would work. Essentially I would get a big fleece blanket and stretch it tight from about the center of the car to the bottom of the rear bumper holding it with rivits or something, and then getting the main panel pretty much layed out, and I was wondering if I did this, and then put multiple coats of resin on it since it would drip down if you put too much on there, would it be rigid enough to be able to drop down and fiberglass over? Pardon my ignorance, but this might not work at all, I just wanted to see if I could maybe go this route. Thanks guys.

 

it sounds like what you want to do will technically work, but I doubt that you will be happy with it's weight. Resin can get heavy if you have a lot of it like you would in a fleece blanket.

 

Thanks for the reply. I was also thinking that if I could get some cardboard and mock up the main panel, I could just glass over that and then go from there. I guess I will just have to get the car up and take a look under there and see what the best way to do it would be.

 

or you could vacume bag your parts for the least amount of resin to be used on each part.

 

1. big flat floor 2. wax paper 3. fiberglass sheeting or matting sheeting would be cleaner. 4. resin. done.

resin dont stick to wax paper. unless you make a zoo out of it.

 

get some alumalite from a sign shop. bingo bango, done.

 

im doing the same project exept im starting to experiment with cf and vac baging i started the way you first stated by using fleece, but ran into a problem. the fleece (which works fine when i make sub enclosures) even when streched as tight as possible will sag once it gets wet and from the weight of the resin. so what i did was made a wooden ribed frame with the curve that i wanted and then got a sheet of that real thin dark press board **** (cant think of the name of it right now) like peg board but with out the holes, and i glued that down over the frame, smooth side out, and held it to the curve until dried and then you cover it with parting wax or you can use car wax so the resin doesnt stick, i also use a pva right before i make the part. then you just lay your pieces of mat and resin till you get the right thickness/strength and with a little work the part should come of the mold fairly easy and you still have a mold to make duplicates if you need. and if your feeling adventurous you can vac bag it to reduce the weight.

 

if you want to save yourself the disappointment make it out of metal.
1. you make it out of FG and you layer it enough to make it withstand vibrations/wind and debris...but it weighs a ton.
2. you get some sheet metal and find a brake and rivet it on.
3.you make it out of FG but try to make it light and dont layer it enough and you spend 5 hours waisting your time be cause it'll break on your first run.
4. give up and run a billet diffuser in the rear bumber.

if you do decide to go with the FG. gets some sheet metal screws and some quality fleece from the walmart. stretch it to the shape you want (you may need to tape up some small pieces of wood to give it the proper shape. apply some resin, let it stand. once it sets pull it off. apply another light coat then sand and drips that formed the first time. apply the matte in how many layers your feel like. then just trim the edges, sand it, then paint it and screw it on.

 

I think I might just go with the alluminum way, I will just make the template out of cardboard, then transfer it. Does anyone know where to get some thin big sheets of aluminum to do this task?

 

seriously, look into alumalite. it's cheaper than aluminum. it's basically aluminum backed plastic.

 

you think its strong enough to not get crazy at 140+ mph?

 

yeah it will hold up, but if you want aluminum or just sheet metal go to home depot or lowes. they should have a steelworks bin set up. lowes normaly has a bigger selection were Im from. other than that look up in the yellow pages for the closed steel mill. or buy online.

 

http://nasaforums.com/viewtopic.php?t=17063

 

http://forums.nasioc.com/forum...52880

 

lots of great info and links, thanks alot guys.