Why does my sub rattle in a ported box??

I have an audiobahn twelve and a 1600 watt pwer acoustik amp, I just put it in a ported box, it only rattles with slight bumps the thing hits hard as crap throughout deep low bass. I think the problem is I need 1.3 cu. ft. ported and I only have 1.25 without displacement and caulk. help..

Why does my sub rattle in a ported box??
I have an audiobahn twelve and a 1600 watt pwer acoustik amp, I just put it in a ported box, it only rattles with slight bumps the thing hits hard as crap throughout deep low bass. I think the problem is I need 1.3 cu. ft. ported and I only have 1.25 without displacement and caulk. help..
it sounded excellent in its sealed box, and when I cover the port with my hand it sounds better, maybe I need a bigger port?? its only three in. round. also if anybody could explain how to wire for four ohms it could be largely appreciated..

there is nothing loose in the box.. the construction is fine

A couple of things. most of the guys here gave you pretty hard advice. I think you better have your sub checked. It may bottomed out before caused by tuning problems.

Things rattle because they're loose. It also sounds like your woofer is overextending.feed it less power.

its not fixed properly ..u got get a hfd 21..in your rear so it tedused the earthing..which will make it better : thank you

You may need a sub sonic filter to keep out the really low frequencies that because the subs to go into excursion.

Below the tuning frequency of the box, the speaker is unloaded which means that it may be made to bottom out pretty easily. A box that's too small will be tuned to a higher frequency, and you will be more probably to run into excursion related problems. If you play lots of deep bass with the power you have, you may want to attempt a sealed box, which will be a little safer for the woofer.

you have a somewhat loose wall in your box.try adding more screws to all the joints and it should stop rattleing

The box is too small while the port is too big.

with a ported box you may want to have the subsonic filter set at 30hz or it may be the wires going from the box to speaker are shaking around a little,i had that same problem for a while till I lined the inside of the box with dynamat

Not all speakers are to be ported. You answered the question yourself when you said it was good in a sealed box.