I totally agree with you be patient and get your seats and then you know you are right, that is what I did and don't forget measure twice drill once or in my case I think I measured about six times until I was satisfied.

Arfon

Get your seats
fix the runners
Fix flat bar across runners
place in position
tack weld flat bar to chassis shielding seat from spatter(:o so you dont get mini burn holes in your seat :o )
remove seat and runner then fully weld
QED

My advice - have the flat bar over length by a couple of inches either side - clamp it up against the bottom of the chassis (i.e. - where the floor will go) then you can play about shifting it nearer to / further way from the transmission tunnel - if required. I certainly had to tweak my seat side-to-side - so actually laid it all up on a piece of chipboard clamped to the bottom of the chassis - and marked it all up before cutting the flat bar.... That also meant I could remove the seat fully to keep it safe from spatter before welding.

Any use? NTDWM - but ETDW someone else on here!

http://www.ebay.co.uk/itm/1511182102...226%26_rdc%3D1

are they IVA friendly? - No headrests

I ended up modyfying my MX5 runners to fit my new seats. Welded the runners to a 40x5 flat bar, which was drilled and bolted to the seat, then welded a 25x25x2.5 RHS crossbar to the runners, one at the front, and one at the back. Spent hours getting my rails in line on the chassis (also 25x25x2.5) then bolted through and through with a M12x75 bolt, with nylocks on the underside of the car.

My passenger seat was easier, because I don't want it to move, so I made a 40x5 flat bar square frame drilled and bolted to the bottom of the seat, then welded some 50x25x3 RHS at the front and back to give the same height as the drivers seat. Set my rails again then drilled through. Both my seats can be removed easily as the nuts are on the underside of the car. Although the only downside is my rails for my seats don't mirror on the chassis.

I'm 6ft tall with long legs, my missis is 5ft 3 with short legs, so for me the seat needs to be fully back, for her, it needs to be fully forward.