Fixing Fiberglass

Started by sv303, May 20, 2005, 02:52:53 PM

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sv303

What product do you recomend for fixing fiberglass race bodywork.  I'm not sure if fiberglass bondo with short hair and a fiberglass mat is flexable enough.  

L8brake731

Boy, Iv'e been waiting for someone to chime in on your thread, as I need to accumulate some tips on repair also.

This must be a secret :D
S. Fukiage
CCS/ASRA  #731

Zac

Fiberglass repair - for the most part I use fiberglass cloth and polyester resin.

I prefer fiberglass cloth to mat because it is usually easier to work with and results in a stronger repair.  Mat does conform to complex shapes better, so it has its use sometimes.

The cheap polyester fiberglass resin  sold at auto parts stores and hardware stores will work fine for most repairs.  Use as little resin as possible that will fully wet the fabric.  Don't use a body filler with the cloth, it is much to thick to wet the cloth and the repair will have no strength.  You can also get high dollar epxoy resins, but the polyester will work just fine.

As far as body filler (Bondo) goes, use it only after the structural fiberglass repair to make it look pretty.  The filler should not add strength.  Use non-reinforced filler and keep it thin for flexibility.  I only use the cat hair (fiberglass filled filler) on a rigid piece, such as filling a dent on a tank.

-z.

Hey Steve, if you have any fiberglass questions let me know.  I've done all too much of it.  Elaine even made the bellypan on the MZ from scratch.

L8brake731

I'll be talking to you. If you hadn't noticed, I took out my belly pan at Phoenix; combination of close tolerances of new body work and running slicks with a bit higher of a profile. I put the icing on the cake when we were packing up and I slipped and dropped the bike going up my loading ramp...... ???
I just can't seem to get the mixture right on the resin and catalyst. Forming is yet another challenge. :-[
S. Fukiage
CCS/ASRA  #731

dwilson

Use fiberglass cloth, the matt is more difficult to work with and is probably less strong.  The resin at home depot isn't as good as the stuff at Pep boys (I can't remember the brands).  Epoxy resin is stronger and the fumes aren't as bad but it's expensive and no one local seems to stock it.  The polyester stuff works well anyway....

Get your busted up pieces and tape them together from the outside, use cardboard covered with trash bag to cover the big gaps or to act as a brace if you have to.  Be sure to have the spot you're going to glass laying flat as possible.  Working from behind have the area that you'll be applying the glass/esin to clean and roughed up with some 80 grit sand paper.  Using 3M Super 77 spray adhesive, spray glue 2 or 3 layers of glass on the repair area.  The super 77 is intert to the resin. Get lots of cheap paint brushes or "tin handled" or "acid brushes" to apply the resin.  Always use paper cups to mix the resin in, I wash out and save my old coffee cups from work.  Mix the resin and apply with a dabbing motion.  Work out the bubbles and try to brush off the excess resin as best you can.  

Fiberglast.com also sells pigments you can add to your resin to give it different colors.  A little goes a long way so order the small can.  

Use a sander to blend your repair into the rest of the piece and finish with 600 grit or better before painting.  You'll probably get pin holes but a few coats of primer followed by some wet sanding should take care of that.....

Did I miss anything?

chasespeed

For quick repairs at the track you can go to an auto paint store and buy a product that fixes the holes in bumper covers. It comes with a repair cloth and  flexible resin. Great for cracks etc, dries fast and semi flexible. You can skim the front side later with a little bondo and primer and its ready for paint. Check out other great repair stuff from 3M or SEM, Duramix from 3m and SEM Weld from SEM http://www.sem.ws/

endoracing

whatever you do, dont use the red "epoxy hardener paste" that you can guy at auto parts stores. It says for polyester resins, but even if you use equal parts hardener and resin, the stuff never dries. Someone told me to use colored hardener to learn the mixture, but I guess they werent talking about the paste kind. Regardless, steer clear of it.

G-reg

Quote from: endoracing on September 28, 2006, 01:45:55 PM
whatever you do, dont use the red "epoxy hardener paste" that you can guy at auto parts stores. It says for polyester resins, but even if you use equal parts hardener and resin, the stuff never dries. Someone told me to use colored hardener to learn the mixture, but I guess they werent talking about the paste kind. Regardless, steer clear of it.



The red stuff is usually for body fillers.. Its not the same catalyst that gets used for fiberglass resin..


--Greg
MW EX#84

endoracing

yeah ... I realize that now ... which is a day late, dollar short :(