FG w/ center divider

I'm prepairing to start a new box with 3/4 mdf and fg. I was wondering how that worked because there is only a 3/4 strip of wood its connecting to in the center didnt know how well that would hold up?  Should i doubble up the wood in the center for more area to connect to, and im going to have the speaker rings about 12in higher than the devider so it can curve down if that makes a diffrence.

The 3/4" divider will be fine. I would recommend that where the MDF divider meets the fiberglass you add some glass to it from inside the box. That way you have it being held on three sides instead of just one. For your second question the fiberglass alone will be more than strong enough to hold your subs as long as you make it thick enough. Keep adding layers of fiberglass until you are unable to make the box flex by pushing on it with your thumb.

Thanks for the info with the divider greatly appricated and helpfull.   I already planned on using the thumb pressure test on it to be sure I have enough layers but for the rings should i also (try) to go from under and glass that to or should it hold with the glass from the top?

Glass the bottom of the ring to. You may end up with overkill but that's better than having your speaker fall out.

Thank you so much that was what i was thinking but wanted a 2nd opinion.   After I get the closing on my new house finished (and get in my new garage) I will post pics of my progress.