Seat Sub Frame

[mfordy]

I'm wanting to fit an aftermarket unstressed fixed bucket seat to my Mk2 Escort.
I'm not using the factory front mount and want to build a sub frame consisting of 2 parrallel tubes running from the tunnel to the sills. (much like most escort rally cars).
See attached pic for more detail - hmm pic won't attach
The aftermarket seats come with brackets that will bolt to the sub-frame. The sub-frame mounting plates will comply with LVVTA standard of no less than 3000mm2.
My question is what size/section tube can I use and is it OK to weld tabs on the tube for mounting the seat brackets (8mm bolts)
Thanks

[Dan]

There is no set size for this job - the Hobby Car Technical manual requires: "bracketry and mounting systems that follow time-proven best practice methods, and incorporate good design and construction techniques."

It is common to use a 25x25x2.5mm box section frame (or similar), bolted down to the floorpan with doubler plates, crush tubes are required if bolting through it. Brackets can be welded onto this.

The solution for Escort rally cars is often to weld bars between the tunnel and sills - there are kits available. This is acceptable, again covered by the Hobby Manual: "Welding seat bracketry to the gearbox tunnel and outer sills is a common and acceptable method of attaching seats into motor-sport vehicles."

When you have an idea of the design contact your local certifier to check he's happy with it, or you can email the LVVTA tech team.

[mfordy]

Thanks Dan