Patching That Hole in the Tub

Missing chunk of fiberglass

Remember that hole and crack I found while installing the Shock Tower Brace?  Seriously, it was last week, just scroll down to previous post.  Anyway, it looks a small child bit a piece off of my tub.  This hole explains why that last screw was not screwing into anything.  I have no idea how long it has been like this, the break looks old.  Time to fix this, even though no one will really see it.

First step is to sand and clean the area.  I used 80 grit sandpaper to give the fiberglass some bite, making sure I got both sides roughed up.

Mesh gives it some backing

I got a sheet of self adhesive mesh to provide backing for the Bondo.  This is great stuff, the mesh holds it shape and it stays in place.   Genius!

Bondo with fiberglass strands

My buddy Jun...yes, that Jun...hooked me up with some Bondo Glass.  It is Bondo with fiberglass strands mixed in.  Perfect for fiberglass repair.  If the fumes do not get to you, the fiberglass should.  You can see that the mesh is in place and ready for the Bondo Glass

Spreading the Bondo Glass

Working with Bondo Glass is quite different from regular Bondo.  The strands of fiberglass make it a challenge just to scoop on to your mixing pallet.  It is a lot like trying to scoop wet noodles with a spoon, most of it gets pulled back into the container.  I mixed a few batches to make sure I do not waste too much of Jun's supply.  Multiple batches also helps with work time as it sets up pretty fast.

I made a small batch to spread on the underside, where the mesh is exposed.  This should help 'lock' down the mesh should the adhesive fail over time.  After a 15-20 minute wait for curing, it is time to sand.

Sanding, sanding, and some more sanding

Pro tip from Jun:  Wet sand the Bondo so the just does not get air born.

Good tip.  I wet sanded the Bondo, working my way from 80 grit, 120 grit, and 320 grit.  This step took a while.  Luckily, I had my laptop in the trunk, just above these images, and I was streaming Netflix while working on this project.

Looks like an orca

I spent about half an hour sanding it down.  A better way to do it would be to shape the Bondo before it totally hardens.  Who says I do things the right way or the easy way?  Still needs a little more sanding before I can paint.

Good old SEM Trim Black

I masked off  and covered some areas and sprayed away.  A few light coats of SEM Trim Black finishes the job. 

Oh wait, I need drill a hole for that final screw.  Since I do not have the threaded insert, the lazy thing to do is to attach a corresponding nut to the hole.  I used some JB Weld to 'weld' a nut on the underside of the repaired hole. There is not much stress in this area.  Heck, for years, there was nothing for the screw to screw into.  So, a glued nut works fine...until it fails.

The access plate goes back in with all the screws holding down the plate.  The shock tower brace goes back on, and we are done.

Total project time was about two hours.  This includes mixing and curing time for the filling compounds.  Oh, and a lot of sanding.