rivnuts or not?

[voucht]

Hi,

I would not use rivnuts because in my opinion, they are way too weak to resist the constraints of a seat + a person, especially in case of a crash.

I think crush tubes are not necessary here. They are on high tightening torques only, and the torque you need to tighten M8 bolts to fit your seat is not high enough for you to need to put crush tubes in the 25x25 tubes the runners are fitted on in my opinion.

I did exactly like you want to do: 2 transversal 25x25 tubes welded to the chassis tubes. Seat runners are fitted with M8 bolts, washers and nylock nuts through these 25x25 tubes, and no crush tubes. So far so good!

Hope that will help

Good luck!