i have a proform box thats made from a hard plastic. my question is how do i stop the box from flexing/rattling.
thanks

 

Is it your box that's rattling, or the back of the cab. There are two vents on the backside of the cab with small rubber flaps, you can see them if you look down between the cab and the bed. Turn your bass up a little and watch/listen to these flaps. When I had two eights in my supercrew, these things would flap and sound like a rattle.
If the problem is in the box, unscrew the woofer, make a brace by cutting a piece of wood (perferebly MDF) that can be fit snug between the top and bottom of the box, and screw it in from both sides.
Maybe try carpeting the box, that might cut down on the resonance.
Hope this helps. Good luck.

 

its the box. everytime i hear the rattle i push on the box and it stops. i was thinking i could put a strap around it to help but that would look ugly. thanks for letting me know about those flaps now i know where i will run my video wire off my back up camera when i install it