I have a 1982 R100RT which has cracks in the fairing by the mirrors. I repaired them two years ago with some polyester based fiberglass resin and glass cloth. A parking lot tip over recracked the fairing and it was apparent that the bond between the fairing material and the fiberglass repair is what gave out. Does anyone have a suggestion for a better repair material or process?
Thanks in advance.
Hey Jim, I'm sure by "fiberglass resin" your mean [B]polyester[/B] resin. It's okay for laminating "new" parts, but not so good for repair work.
In my experience epoxy laminating resin and 1.5oz. fiberglass [B]cloth[/B] are the repair materials of choice on old fiberglass (hand laminated or bulk molded (BMW)). Epoxy adheres much better than polyester/
But you have to take some pain to make sure that the base material is free of dirt and grease, and wax*, and it's important that you rough up the surface around the crack. It will also help if you can groove out the crack into a bit of a "V". When you get ready to make the repair take a bit of the cloth and chop it up into fine pieces (1/4" long or so). * The interior surfaces of the fairing may have a residual amount mold release wax on them.
Mix up the amount of resin you are going to use for the entire repair and then use enough of it, with the chopped up material, to make a putty - smear the putty into the "V" and then continue with the rest of the cloth material.
Your fairing is made of SMC (sheet molded composite) the same as the later Corvettes. A release agent is through out the material and a polyester resin will not hold. You have to use an epoxy based resin.
Thanks, both of you. I'll find some epoxy system to use.
Evercoat is a good all round product. Our local Ace Hardware carries it, and most boat shops do as well; like poly, it's two-part. There are others, West System (Gougeon Brothers), System 3, etc. Epoxy, in general, is not as "cheap" as polyester, but worth every penny. IMO
Just make sure you buy a "laminating resin", not a GLUE.
Addendum: Always apply a small amount of the catalyzed resin to the surface of the part before you apply the cloth, it prevents a "dry lamination", Unlike using mat material it's easier to apply dry cloth than handlie piece of wet, drippy, fiberglass cloth. You'll need three or four pieces of 1.5 oz. (the [I]usual[/I] fiberglass cloth available) to get up to a reasonable thickness Apply one piece at a time and work the air bubbles out of the resin before you apply the next piece. If it starts to get hard to wet out the cloth just apply a little more resin. You don't want to use more resin than the glass needs.
The strength comes from the fiberglass cloth, not the resin. When you're done the cloth shouldn't look like you applied a coat of resin over the back of it. A plastic squeegee helps control even material distribution.
Here's what I mean by "not too wet". A close up of how properly wet out cloth should look; saturated but not dripping with excess epoxy. Note the visible weave.
This is too wet
I tend to agree that the epoxy fiberglass repair is the way to go. However, here is a link to urethane plastic repair for motorcycle fairings that have some video of the repair. As shown in the videos, joint preparation is critical: [url]http://www.urethanesupply.com/PlastiFix-Kits-1/[/url]