Fibreglass Spare Wheel Help

[theshiz23]

Hello gents,

Let me say that this is the 3rd or 4th box I'm building, but it's my first time with fibreglass so if any of you can chime in and help me with a couple questions it's greatly appreciated.

So let me begin by saying that I made a frame for the box, taped the inner wheel well and began to apply some resin with fibreglass mat. I'm happy to say that this first step went pretty well with the exception of not adding enough hardener to make it cure as it should, but everything worked out.

Now, I added a couple more layers of resin and because the box didn't feel sturdy enough to me I wanted to add a second layer of fibreglass mat and this is where things got messy. I ended up applying them just fine and they are currently hardening, but there is a TON of air bubbles below the fibreglass mat.

I don't care if it looks ugly on the inside (obviously) but I want to make sure it's air tight for a good sealed encloser.

1) Am I okay to sand it down once hardened and add an extra layer of resin to fill any holes?

OR

2) Can i put body filler on the INSIDE of the sub enclosure to help seal it up? Would the vibrations make the bondo brittle and break if I did this? First time with Bondo too.

Thanks for the help!

S.

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[AVX Mike 10+ year member]

You need way more than 2 layers of mat to properly build that part of the enclosure. We usually do at least 4-5 layers. Aside from needing to be air tight the enclosure needs to be rigid enough to not vibrate. Yes, you should pop those bubbles and reglass over the entire area. 1/4"-3/8" or more for thickness depending on the curvature of the panels. I hope this helps some.

 

[fasfocus00 5,000+ posts]

depending on the resin, you should be sanding between layers if you're allowing it to fully cure. I personally only use filler to clean up the exterior. if you want to add anything to seal and add strength add Kitty hair or Duraglas. just curious but how are you getting "holes"? are you brushing or rolling the mat once laid down?

 

[theshiz23]

Hi and thanks for the replies.

I ended up grinding down most of the bigger air bubbles and adding about 6-7 layers of mat. Some areas do have bubbles but I believe they are strong enough.

Appreciate the help, and I actually got the bubbles during the cure time... I made sure to dab/stab the mat as I laid it down but somehow the appeared the next day.

I stood on the box and hopped a little and it was fine, I think I'll be okay and it won't vibrate.

Again thank you!