'81 GS450L Cafe Project

[Tom R]

You wouldn't use gel coat in between layers. Gel coat is great if you have a female mold, which you don't. You could spray gel coat as a final coat; but why would you when paint is so much easier?
I'll +1 on epoxy being much easier to work with, albeit a bit more expensive; but for the small amount you need....
One of the problems with epoxy though is it doesn't wet fiberglass mat out as well as polyester - it might be harder to make some of your turns with it. So you might be better off using several layers of lightweight cloth ~ 4 oz or so.
Then long strokes when your sanding it smooth - an epoxy filler is handy here. I've made my own in the past by mixing micro balloons with epoxy with good results; though the pre-made goo is easiest to work with.

If you are planning on making more than one of these - you should make a female mold.

[Hoosier Daddy]

For my GL seat I used locktites 15 minute two part epoxy, mixxed it and then quickly thinned with rubbing alcohol to a "thin Paint" consistancy. Then painted it onto my foam and let it cure. After about 3 coats it totally sealed the foam buck. I then covered it with a sheet of tin foil for an extra measure.
I layed my 5 coats of glass cloth with standard styrene resin and once that cured was able to pop out my buck in one piece.
I even passed it onto a member on a different forum and He used to make his seat, so I know it held up.

[gjohnson]

Why would I not just use the male mold and go over the top of it to make multiple seats?

[Tom R]

Are you covering the whole thing with vinyl? I assumed the tail piece would be showing. If you are covering the whole thing then you're right, why not.
If you're making multiple seats it seems the finish work would be much faster if you only had to fair the mold once (female). Then you could use gel coat for a perfect finish every time. Again though, you only have to fair it if it's showing.

[Hoosier Daddy]

Yes, you don't have to.... but it's a PITA to get the glass smooth enough to paint without a female mold. Lots of sanding and any exposed glass would show big time. I used just the male buck but covered the entire seat with foam & vinyl.

[spyug]

The easiest and best method in my mind is to glass over the foam "buck" with glass cloth and epoxy resin if you want a permanent base for multiple reproductions.

As mentioned it is a bit more expensive than using the polyester resin but cheap enough if you want to do it right for the future and multiple reuses.

One the epoxy hardens you can glass over with polyester resins with not difficulty.

The big thing to note is that once the buck is complete the surface is as smooth as you can get it. If it has any dimples or divots the layered glass/cloth ( for your molded seat) will stick to it. Smooth it and paint it so nothing can stick to it.

Hope this helps.

cheers,
Spyug

[gjohnson]

Absolutely, thanks for the advice guys. I took the weekend off to have some fun while a friend was in town. I should have some more pictures of progress up tonight

It will probably be best to use this "buck" to make a female mold that I can take multiples from? I am also toying with the idea of wrapping the entire piece of foam in fiberglass to make it all one solid piece. The only problem is, I was planning on hiding some of the electronics in the tail section to open up the battery storage area and give the bike a cleaner look. Decisions decisions.

[Hoosier Daddy]

I have seen removable pads (velcro) with a trap door or opening at the bum stop that allows access into the hump for that...
Just sayin.

[gjohnson]

I am thinking that is the way to go as well, maybe put the trap door on the bottom of it I can remove a couple of bolts and have the top cover come off completely and still have a fiberglass seat pan, Kind of hard to explain ill draw a visualization in a bit.

[gjohnson]

Here's a quick sketch of what I have planned, any feedback on my idea would be great. the bottom panel will slide into the top cover and then be held in place by 6 bolts with metal guiding sleeves, I plan on using washers inside of the fiber glass to reinforce it. I just don't know if the seat will be strong enough? Under the seat section I might have to build some supports.



Don't mind my chicken scratch lol.

[Hoosier Daddy]

So what is your reasoning for "wrapping the entire piece of foam in fiberglass to make it all one solid piece." ? Seems like a lot of unnessecary work to me, but you may have something in mind.

[gjohnson]

I was thinking of different ways to do it. If the entire piece of foam was wrapped it would have a hard time flexing/cracking, but I couldn't move the battery into the rear bump.

[gjohnson]

Whew, just finished 3 layers of fiberglass. Lets hope it turns out!

[verde]

Whew, just finished 3 layers of fiberglass. Lets hope it turns out!

Guess I'm just a little late to chime in! Did a battery box and seat pan out of fiberglass on my triumph. Foil tape for the base of the pan was worth the extra cost, much easier to work with than kitchen foil, especially on the vertical sections and what not. Something you could still do if you want: For anchor points, I glassed in t-nuts. Just gotta leave a bolt in when you do it to keep the threads clear. Might work well for your cocktail napkin sketch 2-piece idea. My seat build: http://www.youtube.com/watch?v=Q14K_sny5YQ

[gjohnson]

Very cool video, thanks for posting it up.