Sofa Floor Attachment

[Capt Bravo]

For the second time since we have owned the coach, the sofa has come loose from the floor in my 2005 WRV36MDDS. It was originally attached with four 1/4 lug screws. The first time they came out (dumping the occupants of the sofa onto the floor) I replaced with 5/16 lug screws and now with 3/8 lug screws. Since the sofa is also a passenger seat (with seat belts) it seems strange to not have been more securely attached to the floor.
I'm not sure how much clearance there is between the floors (the sofa sits on a raised floor) but was wondering if some sort of dry wall bolt may work?

[Heater]

Lindater Hollo bolts would probably work. We use them in the steel industry all the time for attaching tubes.

[EngineerMike]

Mine is thru-bolted w/carriage bolts, head visible on underside of slide floor, thread up. If you have a reason to mess w/the nuts, change them out for nylock type. The fairly flat, rounded head of the carriage bolt slides in no problem. You might have to torque them up a bit to pucker the sheet metal on bottom, your call. Use the existing holes for pilot to drill thru from the top.

[GMDavidson]

On my 2001, my sofa was loose and I didn't like the way it was mounted. I installed two angle irons (one on each side of the sofa) to the floor with multiple lug screws, then bolted the sofa to the angle iron. That was more than a year ago and the sofa is secure.