Fender Well Crack Repair
When the old chunk of resin and strand came out, it left a hole in the fender. Before I started the repair, I wanted to see what I was dealing with on the exterior. As you can see, there is plenty of filler around the crack. So my goal is to repair the underneath with a solid layer of fiberglass cloth and deal with the hole during body prep. The cloth repair will form a backing to fill the hole with putty and build on the existing exterior repair ...that's the theory at least.
The repair was straight forward. I used a 2" drum sander and 5" sanding disk (both 80 grit) to widen out the crack area and remove damaged fiberglass. The crack along the arc had grown beyond its repair and I had to remove quite a bit around the L-bend. The yellow area is the body filler on the other side. By this time, the fiberglass was getting thin around the L bend, so I prep sanded using my hands and 36 grit sand paper to give the epoxy some surface to bite.
For repair material I chose 4 oz fiberglass cloth. To replace the removed material, I cut several small squares and rectangles ranging from 0.5" x 0.5" to about 1" x 2". For reinforcement, I cut some strips from a 2" wide roll of 10 oz fiberglass tape.
I used West Systems epoxy with the 205 hardener. To keep the epoxy from running, I added their colloidal silica, a structural thickening agent, until the it was about the consistency of ketchup.
Here's the repair with the small pieces replacing the removed material. I laid them in random orientations for additional strength.
This shows the 10 oz reinforcement strip covering the random pieces. I'm not sure how much strength it added to the repair, but it did smooth out the repair area. After it hardened, I sanded it to remove any stray fibers and bring down the tape edge flush with the fender well. Given its location, I didn't worry about getting a smooth even finish.
SUMMARY: This job was a 3 out of 10. The hardest part was cutting and placing the smaller pieces of fiberglass cloth. I repaired the other crack the same way. Since then, I've painted the fender well with undercoat. The repair is readily visible under the coating, but I think it looks better than the crack, and is certainly more sound.
Restoring the engine bay included the inner fender wells. Because I was in there to access the staples holding the dust seals, I went ahead and removed all the old dirt, paint and undercoating. I noticed an area over the fender arc that looked like excessive undercoating. After heating it up, I used my thin chisel to scrape it away. Instead of undercoating, an old chunk of resin and fiberglass strands fell out in a clump. This was covering a large crack. There was another large crack near the bonding seam on this fender that I already knew about because it was exposed. Both of these cracks had been previously repaired on the exterior side and were not visible. I decided to reinforce both cracks from inside the fender well in hopes of keeping them contained. This walk through focuses on the larger crack, but both were repaired the same way. I'm no expert at fiberglass body work, so I was thankful the area in question was not easily visible.