fiberglass repair


Old 07-23-02, 09:14 PM
Visiting Guest
Posts: n/a
fiberglass repair

I have a 4 inch crack on my conversion van top that I hopefully can fix myself. Can anyone tell me what or how to go about fixing this? Can't afford a body shop job. Thank you.
Sponsored Links
Old 07-23-02, 11:08 PM
Visiting Guest
Posts: n/a
It's pretty easy, but you'll need a good disc sander/grinder & a few other basic bodyworking tools.

If you've ever repaired a drywall crack, you'll know exactly what to do. The theory is the same, only the materials are different.

Grind deep in to the crack w/ a 4" grinder. You want to make a trough along the length of the crack about 1/4" wide and at least 1/2 as deep as the base material is thick. You want to remove the gelcoat & penetrate about 1/16"-1/8" in to the base material.

Using a 36 grit sanding disc, grind the area surrounding the crack, about 4" on either side.

Head to the local autobody supply or boat shop & pick up some fibreglass resin, fibreglass matting & lightweight autobody filler. Pick up a cheap "cheese grater" file while you're there.

Mix the resin according to the directions on the can & spread it in to the crack & the area surrounding the crack. Cut a section of matting about 2" larger than the crack all the way around. Bed the matting in the resin w/ an autobody filler spreader.

Allow the resin to harden.

Mix & apply a second coat of resin to the repair area.

Cut a larger piece of matting & embed it in the resin.

Allow the resin to harden.

Sand the repair area w/ 36 grit sandpaper. If possible, use a DA sander. You can do this by hand w/ a sanding block, but it takes forever.

Finish the repair w/ autobody filler. Mix the filler according to the instructions on the can. Apply the filler as smoothly as possible. Once the filler is applied & begins to harden, rough shape it w/ the cheese grater file. *This step may not be necessary if you were very careful when spreading the filler.*

Once the filler is fully hardened, blend it in to the existing shell.
Begin using 40 grit sandpaper for the initial sanding & work your way up to 320 or 400 grit paper for finish sanding.

Apply a good primer & paint & you're back in business.


Wear appropriate safety equipment when grinding & sanding. This means safety glasses & a good dust mask. Good gloves & long sleeved shirts are also a must when working w/ fibreglass.

You might want to head to the local public library & look at a few autobody repair & or boat repair books to get a better idea of what's involved before you begin. A picture is worth a thousand words & I don't have any body repair pics to post here!

Good luck!
Old 07-24-02, 11:43 AM
Visiting Guest
Posts: n/a
fiberglass repair

Thank you for your help. I am going to the library to see if I can find a book that might help. I had the general idea in my head how but wasn't sure. I read about a product called Plasticoat and wasn't sure if that was the right technique or easier. Thanks so much.

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

Thread Tools
Search this Thread
Display Modes