Fiberglass work

I have an tourpak for my 750 that has some cracks and needs some glass work. I have ground down the area around the cracks, so the buildup of glass will be more or less level with the surface.

What is the best way to prep the surface. It is all sanding, but what, if anything should I use to clean the surface.

Thanks in advance

Ken

 

Is the tourpak fibreglass or ABS plastic ?

 

I am not really sure, but it might be ABS. When I grinded it down with the Dremel, it came off in black flakes.

If it is ABS, is fiberglass the best way to repair it, or would you recommend something else?

 

Auto parts stores sell 'bumper repair kits', that use a type of abs compound. That would be your best bet.

 

I've had good results using fibreglass over cracks to repair the fairings on my XJ900. Just use an orbital sander and medium coarse pad to clean the surface back and put some etch in for the resin to grip too. Not sure if the plastic on my fairing is the same as your' tourpak though.

 

I've made hoods and bumpers for cars, fiberglass gets hot while curing. I'd be concerned with the abs melting, while the polyester resin hardens. I've had good luck cosmetically with bondo mixed with fiberglass strands, but I doubt that it would have much strength. I've read that some guys have god luck using woven fiberglass cloth soaked in polyurethane. Woven fiberglass is by far the strongest, set aside carbon fiber. You may want to consider using aluminum foil as a heat barrier and fiberglass the cases from the blind or inside, pop rivet it in place after it gets hard then use bondo on the cosmetic side. Wolven glass w polyester resin is very strong and flexable. (they make hunting bows and fishing poles out of it).
Stay away from that chopped glass matting like they use in glass pack mufflers and home insulation rolls. The good stuff looks like curtain materiel. Your enemy is air bubbles the trick is using pins to pop them (or in a perfect world) a syringe. I used to use 6 layers and 6 days. (one per layer)

 

Fibreglass can get real hot if it is over catalysed, particularly if ambient temperatures are high.....can actually even catch fire. You should be catalysing at about 1% ie 1 part by volume catalyst to 100 parts by volume resin for general purpose polyester resins...don't lay on more than 2 layers at a time, before letting cure for 12 hours. You can bump that up to up to 2% if conditions are cold.
If you're laying the fibreglass over a crack use a "prickle roller" to get most of the air out. This is a specialist tool with very stiff bristles pointing out, available from boat building supplies stores etc. Pretty cheap though. To get the remaining air bubbles out use a "bolt roller" which is just a drilled out bolt on a wire handle. This also pulls excess resin out of the job, making it lighter and stronger.

 

Naturally, like padre points out, you will be reinforcing/repairing from the "inside" or non cosmetic side then filling and remaining cracks or voids with plastic 2 pack putty from the outside, before sanding back and repainting.

 

Thanks all,

I have since bought and used a bumper repair kit. Will see how it holds up in the riding season. The crack in the fairing is double walled and I am unable to reinforce on the backside.

Thanks for all the advice, will keep you updated as to the condition this summer.

Ken