Adhesive to mount fiberglass fenders

**RyanD** · July 25, 2013, 06:09 AM

I read somewhere to use 3M window urethane to glue the fenders to the mounts. It looked pretty good until I loaded the car on the trailer and started driving. The fenders came loose and were flapping in the wind. There was almost no adhesion to the fiberglass, and it wasn't hard to pull the material off the mounts. I had been 3 days since I applied it, so it was cured.

The material that Brammo used was much harder and yellow-ish in color. Then they put something similar to the 3M window urethane on top of it. Anyone know what material they used or anything that would work better?

**RyanD** · July 25, 2013, 08:45 AM

I think I'll sand the bottom of the fender to rough the surface and then try epoxy putty like this.

Shop Oatey 4 oz Epoxy Putty at Lowes.com

**bolus** · July 25, 2013, 09:47 AM

Mine started to pull up and my theory is that I did not rough up the surface enough and the resin in the carbon fiber still hadn't cured completely since they were only a few days old. On the area that started pealing up I applied some 2 part epoxy (basically gluing the 3m urothane to the fender) like this and now I can lift up on it with a good 30-40 lbs of force and it seems nice and set.

I think the fender needs to be completely cured, completely cleaned and have a roughed up surface to aid in adhesion of the 3m urethane. If I started from scratch again, I'd do this, then apply some epoxy centrally and then the urethane over this.