Elevator bolts are even better, but they require a nut underneath to secure them. Unless you're dropping the belly pan, you won't be able to use nuts and bolts.
These screws tap the steel below the floor, using the chassis member, itself, as the nut.
The manufacturer recommends using in frame members as thin as .125". Our experience is that they hold securely in frames down to .100" thick.
The manufacturer also states that they will self-drill and self-tap up to .250" material, but our experience is that to avoid aggravation, you should pre-drill all holes with a #16 bit and pre-tap all frames .125" thick or thicker. (we sell the drill/tap kit).
Screws are 1-5/8" long. The flat Phillips heads countersink themselves.
Sold in bags of 25 screws.
Warning: A self-tapping screw in thin material is inherently weaker than a bolt with a nut on it. If the steel you are fastening to is too thin or there is a lot of force working on the screw, we recommend a fastener with a nut. On Airstreams, do not use these to attach the aluminum wall U channel to the ends of the chassis outriggers. You must use bolts and nuts in that location.
Smart design features:
- Point has precise cutting edges to improve drill performance with less effort.
- Special winged fasteners ream a hole in the plywood preventing thread engagement during drilling.
- Flat head design countersinks and seats flush in wood.
- Electroplated epoxy coating provides excellent corrosion resistance and lower tapping torque.